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Technician Training for the Maintenance of In Situ Mosaics

1. MOSAIC ID Tessellatum lacunae Cracks Bulges Depressions Detachments between mosaic layers PREPARED BY DATE 20 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 LEGEND CONDITION ASSESSMENT MAP NO 2 SURFACE DETERIORATION MOSAIC ID Detached tesserae Deteriorated tesserae Deteriorated mortar between tesserae Stains Incrustations Efflorescence oz PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 21 LEGEND CONDITION ASSESSMENT MAP NO 3 PRESENCE OF BIO DETERIORATION AGENTS MOSAIC ID Micro organisms Vegetation Tunnels or entrance holes made by insects and other animals Juuuuuluuu PREPARED BY DATE 22 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 LEGEND CONDITION ASSESSMENT MAP NO 4 DETERIORATION OF INTERVENTIONS MOSAIC ID Deteriorated lacunae fills or edging repairs Deteriorated mortar between tesserae Re detached tesserae or detached tesserae of a re l
2. sobejueApy saueiquiayy uonejedes 51995 2nseld 115 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Plastic netting Plastic netting such as mosquito nets allows liquid water water vapor transport It efficiently separates coarse fill materials such as gravel but it will let finer materials such as soil and sand through It will not prevent vegetation penetration and animal activity but is inexpensive and easily available Woven plastic sheets Woven plastic sheeting used for example to make storage bags strongly reduces liquid water as well as water vapor transport often creating a humid area just below the woven plastic sheet that promotes root growth It only partially prevents animal activity It efficiently separates all fill materials is not too expensive and often locally available Geotextiles and other synthetic fabrics Geotextiles are made to be used underground They are used particularly in civil engineering projects such as road construction to prevent soil erosion for example They are generally expensive and can be difficult to obtain There are many different types of geotextiles and each type has its own properties They are two main categories woven and non woven geotextiles The latter are recommended for reburials Geotextile
3. Revision of the base drawing or photograph Photographic doculmeltatl issuer utis ibn Qe He It RA otn RR Archiving of paper documentation eerte Archiving Data B RUM OE Archiving of digital documentation sedebit Documentation and archiving during maintenance cycles Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 2 MAKING BASES AND MAPS FOR GRAPHIC 42 e H 42 saber AY RAUS 44 Base photographie ae eie ttes in 45 Viclor RN 46 Legend Sen desi daten ott Po ipu Nl GU ott ae 47 Making a base drawing directly using a grid sss 48 Making a base drawing indirectly from a 51 Making a base photograph from a single photograph 52 Single etel tna cut Pto bb ER RUD NUN UR D UOS 52 Base photograph from a single photograph eere 53 Making a base photograph from a photographic
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5. This form must be completed with the site manager It should be supplemented by an overall photograph of the mosaic anda plan of the building indicating the location of the room SITE BUILDING ROOM SECTIONS FRAGMENTS OR LEVELS Use Arabic numerals for sections letters for fragments Roman numerals for levels MOSAIC ID Abbreviation of the site building room sections or fragments or levels EXISTING DOCUMENTATION ABOUT THE MOSAIC AND ITS CONSERVATION References of publications plans photographs drawings and other documents DATE OF MOSAIC EXCAVATION DIMENSIONS AND NUMBERING OF FRAGMENTS SECTIONS OR LEVELS Use an existing drawing or make a sketch of the mosaic indicating the north and the walls of the room GENERAL OBSERVATIONS ON THE CONSTRUCTION TECHNIQUE Type of pavement decoration materials colors tesserae sizes etc PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 11 If need be one add to the abbreviations of the site building room Arabic numeral 1 2 3 4 for each section when it is necessary to divide a mosaic to document it graphically e a letter A B C D for each fragment of a mosaic that is in several pieces aRoman numeral I Il III IV for each level if there are several mosaics one on top of another level
6. 54 Photographic survey to make the photographic montage 54 Base photograph from a photographic montage sss 57 Drawing the graphic scale of a base drawing or 58 Maki g mapas va a Aio EA EE 60 CHAPTER3 THE USE OF A CAMERA AND COMPUTER IN DOCUMENTATIONL 62 62 5 etr Ep indo Pr 65 General advice about sine isis rerit na ui n lp V 68 epo 70 iv Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 4 CHAPTER 5 PART 2 DETERIORATION AND INTERVENTIONS DETERIORATION S M 77 inlet 77 alum S 77 Bi d teriorati seissioun 81 Natural disasters 84 E REN 84 Humar ACTIVITIES rc 84 Inherent properties of the Materials ssssesssessecssssssssescesseeseceessecsseesseccseeesseeses 85 INTEBVENTIONS sso iasantetdestaetisrssonietsssriceadiclesivinnisiasinvcstersiune 86 Levels of conservation treatment csscssscsssecssecssecssscssscesseesseeseceesnecsnecsseeesseesseense 86 First aid OF ENGNG CIC CAN
7. eui uaye 21250 991 513 1 uo paseg Jaded ydeib ajeds 0 resou ay pue resouJ y o3uo spus Jo e dn 196 e pou1ew aseq aseq aseq jo adh Sso 0Jd ay 54915 43 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Base drawing 44 Measured drawing page 48 A base drawing can be obtained directly by setting up a regular grid of strings onto the mosaic and by drawing the mosaic directly to scale using graph paper based on measurements of the mosaic taken using the grid Traced drawing page 51 A base drawing can be obtained indirectly from a montage of photographs or a single photograph To make a montage the mosaic is photographed sector by sector and these photographs are assembled to create a single image The mosaic is then drawn on tracing paper that is laid over the photographic montage or single photograph producing a drawing of the mosaic Existing drawing A copy of an existing drawing of the mosaic found in a book in archives or given by the archaeologist or the site director can also be used An existing drawing might have to be modified if it is outdated and no
8. pue Ajipeay pue ainysiow 5 sureyurelWw KyAn e jewjue pue u1w0J5 0 euoud ssa IesouJ Y KyAn2e pue 0 Sjue d pue spaas sobejueApesiq pue Ajipeay Ayjiqeys ainyesaduua pue ainjsiow poob sureyuley yodsues SMO sobejueApy sjevayew J 113 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Other natural materials Some friable and weakly agglomerated rocks and volcanic earths such as pozzolana or tiff a calcareous sand found in Tunisia are also used as fill materials These materials are quarried and sold directly in powder form Both materials allow good liquid water water vapor transport provide a good temperature and moisture stability and especially in the case of tiff do not promote vegetation growth Both materials are very inexpensive when purchased directly at their place of extraction but their availability is often localized pozzolana is found almost exclusively in Italy while tiff is found in Tunisia On the other hand when placed in direct contact with the tessellatum pozzolana w
9. SALT CRYSTALS D SS NOU YS p xi OSY paras FIGURE 15 Salt crystallization Contraction dilatation cycles Mosaic materials can increase in volume if they absorb water or if there is a steep temperature rise This increase in volume or dilatation generates the compression of the materials within the mosaic causing cracks and detachment of its uppermost layers Freeze thaw cycles When the ambient temperature falls below 0 C the water contained in the mosaic materials turns into ice causing them to fracture 80 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Bio deterioration agents The impact of animals and plants is also a significant cause of mosaic deterioration Figure 16 Climate influences the type of animals and plants found at a given site and the severity of damage they can cause Certain animals and plants will cause far more severe damage than others Table 2 u QUIM NS Nii 5 NT NN SEA c WAIN N ALGAE MOSSES LICHENS ag L nannte oO Oe TOUO SENS m ete yo 23 2 2 SS aw FIGURE 16 Deterioration caused by animals and plants Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 81 5 15 sjaued yoddns 1 1
10. Location of the metal reinforcements of the support panels Parts detached and stored elsewhere Other types of interventions Reburial outline Drainage openings PREPARED BY DATE 16 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 LEGEND MAP Hentai ADDITIONAL SHEET MOSAIC ID o PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 17 Data Form 3 Condition Assessment Data Form No 3 is used to record the different types of deterioration presently observed on the mosaic as well as the condition of past interventions carried out on or around the mosaic Current exposure conditions of the mosaic are also recorded This information serves to assess the general condition of the mosaic and the degree of urgency of any intervention Data Form No 3 is accompanied by separate graphic documentation in the form of four location maps and their legends Condition Assessment Maps No 1 No 2 No 3 and No 4 The location of different types of deterioration is mapped on each of these maps The four Condition Assessment Maps are Map No 1 Structural Deterioration
11. dbW uonuaAJa1u ON D D aseud Apnis Y 3uauussassy ON W104 10353 Y 1 Z ON WOJ DDG A 5 1 2 x10M LSWd ON A 21 y Jo 1 21 5 07 ALINOLLNY FIGURE3 The maintenance process and its documentation through time 41 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 CHAPTER 2 MAKING BASES AND MAPS FOR GRAPHIC DOCUMENTATION Graphic documentation enables the accurate mapping of different types of deterioration on the surface of the mosaic and makes it possible to rapidly assess their extent and to pinpoint the location of interventions Graphic documentation can be carried out either by hand using colored pencils felt pens paper etc or directly on a computer using specific hardware and software Only the first traditional method will be developed here as it is the most widely accessible Indeed creating graphic documentation directly on a computer requires specialized computer training BASES Creating a bas
12. JO 2 9 1 1 216500 JO JU2UJ9AO A Sapi spue 211 seyenbuie3 SJ9 sesip EJnjeN 1 5 1 payesoajap pue patpejaq saunyel4 unre sjuaupejsq suoissa1daq sabjng stesoui uo Hulyjem q pasne ainssaid eoueupaw 5159 Jo 5 sjauum ay 0 anp Jo 5507 239 sMo daays sajow syed s asul sjewiuy suleys aeiassa 1 syed aeume sjuauipejag sabjng yymosb q pasne e rue ua 218 saysng sjuejd sse16 92195591 U20M 2 Je110UJ 9 9 92195591 10119 9 y mo16 1001 Aq pasne ainssaJd e rueupaw S 1493eUI JO UOI eULIOJSUPJ 19 ssoui suaupi aebje sursiueb40 0J21N sjuabe 019 9619559 Je110UJ 9 9 9019559 9 9 sap o MeU1 22334 S De aeume sjuauipejag sabjng 5 JO sap o Uoneje p uonoejuo aelassa PILOA suonejsnayu a2u225210 J3 eueuioueug uirew Sap o 1p M 01 uonezi e15 1165 suisiueu e sejduiex3 jos buijood 1936 pum yes auey 540 esu uonesuapuoo 1942M MO
13. Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 SETTING UP THE GRID e L fff ff D SY 2222 ITT IFAT BASE DRAWING INTERSECTION POINT OF THE ID wan TITLE GRID 0 N HS SHH DATE PREPARED BY BASE MADE ON 10 2004 FIGURE4 Measured drawing using a grid Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 49 Attach a sheet of graph paper to the drawing board with masking tape and put a sheet of tracing paper over it Choose a scale for the drawing according to the size of the mosaic and the paper format used A3 or A4 A scale of 1 10 or 1 20 1 cm in the drawing to represent respectively 10cm or 20cm in reality is often advisable With a pencil draw on the tracing paper the outline of the mosaic its simplified design and the outline of the walls of the room if they are close by The mosaic must be drawn square by square by taking measurements of the mosaic using the grid and transferring them to scale onto the tracing paper using the graph paper grid If the mosaic is large it can be divided into sections Each section of the base is then drawn on a separate sheet These sect
14. Mortar composition Facing with adhesive Removal and resetting tesserae with facing Removal of metal reinforcements in support panels Treatment of metal reinforcements in support panels Drainage openings Reburial of a part of the surface PREPARED BY DATE 28 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 LEGEND MAP iaa ADDITIONAL SHEET MOSAIC ID O PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 29 Revision of the base drawing or base photograph After the interventions have been carried out the mosaic is clean and stabilized its surface is therefore more visible An inspection should be made to see if there are any differences between the base drawing or photograph that was already used to make the Maps and the true outline and decorative motifs of the mosaic which are now entirely visible If there are significant differences the base drawing will be corrected or a new base photograph will be created This corrected base drawing or photograph should be dated and used to make the Maps during subsequent maintenance cycles 30 Technician Trai
15. photographic by taking photographs recorded on the photograph log These three documentation formats can be created by hand or using a computer All documentation collected during a maintenance campaign can be divided into three successive phases 1 Study phase 2 Planning phase 3 Intervention phase Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 STUDY PHASE In this first phase information on the construction of the mosaic during Antiquity the work done on it in the past and its current condition is collected This data is recorded in written format on three data forms Each of the three data forms is accompanied by illustrative documents including maps with their legends photographs etc Data Form No 1 Identification page 11 supplemented by a building plan indicating the location of the room where the mosaic is situated and an overall photograph of it Data Form 2 Previous Interventions 15 with the Previous Interventions Map and its legend page 16 Data Form No 3 Condition Assessment page 19 with the four Condition Assessment Maps and their legends pages 20 23 PLANNING PHASE Work to be done will be planned on the basis of the data collected during the study phase This planning phase is recorded in writing only by completing Data Form No 4 Intervention Planning 25
16. 2013 99 Mortars for mosaics stabilization interventions The quality of any mortar depends of its own characteristics It is especially important that a mortar used to stabilize ancient mosaics as with any good quality mortar should not contain soluble salts and that once set cracking should be limited i e it should be stable and durable over time A mortar used for the stabilization of ancient mosaics should also have additional characteristics It should have a good affinity with the ancient materials and in particular its hardness and porosity should be similar and it should permit a similar movement of water in the ancient materials and in the mortar A stabilization mortar should also be reversible that is it should be removable without deteriorating the mosaic This is why mortars made of non hydraulic or naturally hydraulic lime should be used Because a mortar made of cement or artificial hydraulic lime cannot fulfill the above conditions it is strongly advised not to use them for the stabilization of ancient in situ mosaic In addition a mortar used for mosaic stabilization should have a color and surface texture that do not stand out rather the mosaic surface should always stay visually dominant To choose the most appropriate intervention mortar for a given in situ mosaic its construction technique condition exposure conditions as well as the climate of the archaeological site where it is loc
17. Archiving of paper documentation All data forms base drawings or photographs maps with their legends and printed photographs pertaining to a mosaic must be placed in the same folder or binder All the documentation components for a given mosaic data forms maps and photographs must be listed on the Archiving Data Form Archiving Data Form This data form lists the documentation components contained in the folder pertaining to a mosaic After creating each document during the initial intervention campaign the date it was created should be recorded on the corresponding line in the first column of the form New documents created during each subsequent maintenance cycle are then added to the folder and grouped together by intervention campaign Their date of creation should be written in a new column of the Archiving Data Form Thus there is only one Archiving Data Form per mosaic In summary the documents to be archived during the maintenance of a mosaic are the following e Base drawing or photograph Data Form No 1 Identification and building plan and overall photograph Data Form 2 Previous Interventions and Map with its legend Data Form 3 Condition Assessment and Maps No 1 No 2 No and No 4 with their legends Data Form 4 Intervention Planning Data Form No 5 Current Interventions and Map with its legend Traditional photographic prints and or printed digital photographs with Ph
18. 1 payesouia ag aelassa 0 9190 aelassa payrejaq suoissaJdaq sabjng sjuauiuejag S pe1 aeume 21050 au Jo 5 JO 5507 238 speod suononijsuo M N buiuuejd asn 100g jesoui y JO 1 JO 5507 suoneAe xa 1esow Jo Jay 38 UisljepueA uononjjsap e3uepr e 10 3je1aqi op snojInieJr 5 Jo 5 uonezije1s 4 yes pes peurenuf Sjeuajeui ejenidojddeui jo 95 payndaxa p100d SuonuaAJa1ul ajeudojddeu yymosb 1001 Aq pue sxtesoui uo Bulyjem Aq pasne aunssaid eorueupayw uonezi e1s A yes suisiue40 oJ51ui pue sjuejd Jo u1M045 S322 15 0 pa o11uoouf ros 1932M s pe Says 21 Jo juawabeuew 1004 suoneisnj u VUSO sures 9019559 1 0 JELOW 3812552 9 uonezije1s 4 yes 21650 Jo uoneuloJsueJ JLU 1 001551 5 JE 17111139 jeamjnouby 1105 pue yuasaid sexuejsqns uonnjjod sues 1 5 1 payreyaq sjuauipe1aq suolssaidaq seb ng S pe1 eume
19. Getty Conservation Institute Institut National du Patrimoine Tunis 2013 57 DRAWING THE GRAPHIC SCALE OF BASE DRAWING OR PHOTOGRAPH The scale of a drawing or photograph is the ratio between the distance between two points measured in reality and the distance between the same two points measured on the drawing or the photograph The scale drawn on a base drawing or photograph is called a graphic scale It is a bar divided into intervals with a zero at the left end and a dimension often expressed in meters at the right end It enables one to calculate the actual distance on the mosaic from a drawing photograph of the mosaic 58 There are two methods to make a graphic scale Locate on the mosaic two points a meter apart which are also visible in the drawing or the photograph of the mosaic On the drawing or the photograph find the two points and measure the distance between them using a ruler Draw on the base drawing or photograph a straight line the length of which is the distance just measured with the ruler Mark at the ends of this line the values 0 to the left and 1 meter to the right This bar is the representation of the length of one meter in the actual mosaic The distance of 0 5 m can also be indicated by a tick mark located in the middle of the bar as shown below Figure 6 Eo LL 0 0 5 m 1m FIGURE 6 Graphic scale Measure the distance between two points on the mosaic that are also identifiabl
20. INTERVENTION PHASE The programmed work is carried out during the intervention phase All interventions on the mosaic are documented in written and graphic formats by completing Data Form No 5 Current Interventions accompanied by the Current Interventions Map and its legend page 28 8 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 WRITTEN AND GRAPHIC DOCUMENTATION Written documentation helps to collect information about the mosaic To create the written documentation a series of data forms is used organized by step and subject which must be filled in order to gather information in a complete and orderly manner Graphic documentation helps to precisely record the position of information on the mosaic surface To produce graphic documentation a base is used from which various maps are made A base is a drawing base drawing or a photograph base photograph of the mosaic A map is a record of different data pertaining to the mosaic which are represented by various symbols and colors A map must always be associated with its legend which is an explanatory list of the colors and symbols used on the map Data Forms and Maps are actual tools to collect data about the mosaic enabling the planning and the evaluation of maintenance interventions Technician Training for the Maintenance of In Situ Mosaics Getty Conservati
21. Map No 2 Surface Deterioration Map No 3 Presence of Bio Deterioration Agents Map No 4 Deterioration of Interventions Maps No 1 No 2 and No 3 are used to record the condition of the mosaic itself whereas map No 4 is used to record the deterioration of past interventions legends pages 20 23 The condition of a mosaic should be regularly monitored through time At each new inspection a new Data Form No 3 Condition Assessment should be filled out recording only the new deterioration phenomena that have occurred since the last inspection or the last intervention 18 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 DATA FORM NO 3 CONDITION ASSESSMENT STUDY PHASE MOSAIC ID INSPECTION TYPE PRESENT EXPOSURE CONDITIONS In open air Reburied L Walked on Parts not excavated or inaccessible Initial inspection L Under a removable cover Maintenance cycle Under an open shelter Under a closed shelter During the initial inspection check the boxes of all the deterioration phenomena that are present During maintenance cycles only indicate new deterioration phenomena that have occurred since the last inspection or last intervention STRUCTURAL DETERIORATION Tessellatum lacunae Cracks Bulges SURFACE DETERIORATION L Detached tesserae
22. Some volcanic earths and rocks such as pozzolana are naturally able to chemically react with lime in the presence of water and can give a mortar a strong hydraulic set Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 95 Factors influencing the properties of a lime based mortar Choosing the type and quality of each of the mortar ingredients binder aggregates and water and their respective proportions will determine the characteristics and performance of the mortar during its preparation application and when it has set Non hydraulic and hydraulic properties Depending on the type of binder and aggregates mixed together a mortar can be non hydraulic i e it needs to be in contact with air to set or hydraulic i e it sets in contact with water A non hydraulic lime based mortar is obtained by mixing non hydraulic lime and inert aggregates There are several ways of obtaining a hydraulic lime based mortar It can be a mixture of non hydraulic lime and aggregates giving hydraulic properties to a mortar or a mixture of natural hydraulic lime and inert aggregates or aggregates giving hydraulic properties to a mortar The degree of hydraulicity of the mortar varies depending on the types of lime and aggregates used In general hydraulic mortars are harder than non hydraulic ones and they can set even if they only have limited contact
23. Deteriorated tesserae L Deteriorated mortar between tesserae PRESENCE OF BIO DETERIORATION AGENTS Micro organisms Vegetation DETERIORATION OF INTERVENTIONS Deteriorated lacunae fills or edging repairs Deteriorated mortar between tesserae Condition Assessment Map No 1 Depressions Detachments between mosaic layers Condition Assessment Map No 2 Stains Incrustations Efflorescence Condition Assessment Map No 3 Tunnels or entrance holes made by insects and other animals Condition Assessment Map No 4 Re detached tesserae Deteriorated support panels Deteriorated support metal reinforcements Reburial Presence of vegetation Loss of fill materials Deteriorated separation membranes DETERIORATION OF INTERVENTIONS AROUND THE MOSAIC Clogged drainage Deteriorated cover or shelter Stabilized walls with new deterioration Damaged access barrier Other OBSERVATIONS ON THE CONDITION ASSESSMENT GENERAL CONDITION OF THE MOSAIC Good Fair Bad Date recommended for next inspection No intervention required L Date recommended for intervention Intervention required PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 9 LEGEND CONDITION ASSESSMENT MAP NO 1 STRUCTURAL DETERIORATION
24. 119 The deterioration of mosaics re laid on reinforced concrete panels and replaced in SitU ceessssesssssssscssecssessecsseccsecsssccsseecssccssceeseeeseeesees 121 In situ maintenance treatments of mosaics re laid on reinforced concrete panels ee eee teenteentenntennttnnnis 122 APPENDIXA LIST OF MATERIALS NEEDED FOR DOCUMENTATION aoo etankacancansauos onines ooa nc torto 124 APPENDIXB LIST OF MATERIALS NEEDED FOR AN INTERVENTION CAMPAIGN eene tnntnns 125 VI Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 ACKNOWLEDGMENTS The current team engaged in training technicians for the maintenance of in situ mosaics for North African countries within the framework of the MOSAIKON Project would like to recognize the fundamental role that Jeanne Marie Teutonico Associate Director of the Getty Conservation Institute and Aicha Ben Abed Regional Coordinator of the MOSAIKON Project have had in creating MOSAIKON and this training course Lotfi Belhouchet director of the site and museum of El Jem Tunisia has worked tirelessly to help make the course to be held at this site possible Several former staff members of the Getty Conservation Institute have contributed to developing the training methodology and teaching materials since 2001 We are grateful for the help provided by Dr Elsa Bourguignon between 2002
25. All files once uploaded to the computer such as digital photos see Supplemental Manuals for Digital Photographic Documentation pages 3 6 should be renamed Their new name is composed using the method explained hereafter This file name format should also be used to name files created directly on the computer such as photomontages of digital photos see Supplemental Manuals pages 11 22 or photo layouts see Supplemental Manuals pages 7 10 A file name comprises 5 parts Underscores should be used between each part The following model should be followed so that all filles may be automatically organized in alphabetical and chronological order by the computer Part 1 The Mosaic ID used in all written documentation comes first For file names dashes symbol rather than forward slashes symbol should be used between the different parts of the ID because computers do not accept forward slashes in file names For example DG Th1 11 will become in the file name DG Th1 11 Part 2 Next comes the date when the photo was taken or when the document was created The date should be written starting with the year followed by the month and the day using dashes between each part For example May 15 2006 will be written in the file name as 2006 05 15 Part 3 After that the abbreviation for the category of the photo or document that is its general theme should be added The six possible categories and their abbreviations are a
26. Institute Institut National du Patrimoine Tunis 2013 91 MORTARS Mortars are used for all mosaic stabilization operations A mortar is the combination of a binder lime etc aggregates sand gravel etc and the appropriate quantity of water This mixture is used while still soft and malleable and fulfills its structural function when it sets and becomes hard Binders A binder is a material that keeps aggregates together when the mortar is set and has become hard Binders can be divided in two categories non hydraulic and hydraulic binders non hydraulic binder needs to be in contact with air to set whereas a hydraulic binder sets predominantly when in contact with water Non hydraulic binders Lime putty non hydraulic lime putty Making lime putty starts with burning pure limestone Limestone is transformed into quicklime by combustion Quicklime is then transformed into lime putty when water is added This latter operation is called the slaking of quicklime Lime putty which is generally white and thick is obtained by slaking quicklime with excess water Lime putty keeps for a very long time years and its properties improve with age if kept under water When lime putty is exposed to air it hardens and is transformed into a material that has the same composition as the original limestone Figure 19 Hydrated lime non hydraulic powdered lime Hydrated lime is made the same way as lime putty i e by burning pure limest
27. Plastic netting mosquito net Geotextile Gauze or light weight cotton cloth Adhesive for facing Small drill with discs for cutting Anti rust paint and solvent Small brush White cement Small burner electric gas Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 25 The Getty Conservation Institute Institut National du Patrimoine 9 780983 492252 TT
28. Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 Amore or less simplified outline of the motifs to be created could be incised or painted on the surface of the last preparatory layer or of the bedding layer to guide the mosaicist when inserting the tesserae The stratigraphy of the preparatory layers supporting the tessellatum of a mosaic can vary depending on the construction period and the local traditions The following description corresponds to the most common Roman tradition The bedding layer is generally placed on one or two preparatory layers which are usually made of lime based mortars The layer immediately below the bedding layer is called the nucleus the layer below that is called the rudus The rudus is normally thicker and made of a coarser mortar than the nucleus The foundation of the mosaic is made of an initial layer called the statumen used to create a leveled surface and to stabilize the ground to avoid settlement and deformation The thickness of the statumen can vary and it is often made of large stones pushed into the ground or set witha coarse mortar In some mosaic pavements or sometimes in mosaics on vertical surfaces a small mosaic panel usually less than a square meter made in opus vermiculatum is inserted This panel called the emblema is generally made separately on a stone slab or large ceramic tile in a workshop prior to the making of the mosaic into which
29. a CD ROM drive etc The screen or monitor lets one see what one is doing The keyboard makes it possible to communicate with the computer by writing text typing commands etc Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 71 The mouse is a small box that is held under the hand It usually has two buttons on the top a main button on the left and a secondary button on the right The action of briefly pressing any button on the mouse is called to click Moving the mouse with one s hand will make a cursor on the computer screen move A cursor is a kind of marker that indicates which area of the screen will react immediately to the instructions that are given to the computer On most computers the basic appearance of the cursor is a small arrow By simultaneously pressing a mouse button it allows one to select objects visible on the screen and to move them etc The cursor can also change its shape when it becomes a small vertical line in a text for example it is then possible to write change and delete text Laptops have a touchpad built into the computer which replaces the mouse It is usually located under the keyboard and the buttons below serve as mouse buttons With a touchpad the cursor is moved on the screen by moving one s finger on the sensitive surface of the pad Computers are usually equipped with one or more drivers oft
30. addressed the deterioration and loss of in situ mosaics At the same time both professions have recognized the importance of conserving all these figurative and geometric pavements whole and in their original architectural setting in order to better preserve the integrity of their cultural values and authenticity for the future Preservation of mosaics in situ however requires a new approach to archaeological sites one that recognizes sites not only as resources for current archaeological research and potentially for museum collections but also as finite cultural resources whose values derive from their place within a landscape and that can benefit the public visiting the site and the surrounding community In addition to a different approach better preservation of mosaics in situ and sites in general also requires people trained and employed specifically to manage and maintain a site on a daily basis In many countries there are not as yet enough people with these skills able to work on sites Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 IX whether they are specialized workers or technicians professionally trained conservators or trained site managers The training of technicians for the maintenance of in situ mosaics was undertaken as a first step towards the training of qualified personnel at all levels to maintain archaeological sites In
31. current developments in photography only the use of digital cameras will be addressed here Any digital camera regardless of brand or model has a memory card and a battery with its charger It also comes with an instruction manual a small booklet which should be read before using the camera in order to properly adjust the camera settings In a digital camera the light coming from the object to be photographed is captured by an electronic sensor that converts it into a digital image The image is a digital file that is saved on the memory card inside the digital camera These images can later be uploaded to a computer see Supplemental Manuals pages 3 6 A digital camera automatically assigns a name to every digital photograph This name is generally made of a sequence of letters which varies depending on the camera type followed by an ascending number The number of a digital photograph can be found when the image is displayed on the camera screen in view or playback mode button gt and when the option to display the image information has been selected Figure 9 This photograph number is also visible when the photograph is uploaded to the computer It is this digital photograph number that will be used to record the photograph on the Photograph Log and on the Photograph Map VIEWFINDER MENU BUTTON CONTROL DIAL MEMORY CARD COVER SCREEN PLAYBACK BUTTON DIGITAL TERMINAL FIGURE9 Digital reflex camera seen fr
32. glues each having specific characteristics that determine its choice and use When resetting the tessellatum and stabilizing the intervention area after removal of the facing it is necessary to use a mortar which contains cement in order to insure a good bond with the concrete support panel A mortar containing only lime as a binder is not effective to fill the cracks and voids left by the steel bar removal and to reset a tessellatum section back on a reinforced concrete panel The treatment of damaged reinforced concrete mosaic panels replaced in situ is very often a complex task involving various operations that require experience from whomever carries it out The in situ stabilization of the most damaged areas of a reinforced concrete panel can still be considered a maintenance operation However the long term conservation of such panels may require their complete dismantling and removal to a workshop the removal of the old reinforced concrete support and the re laying of the tessellatum sections in situ on new lime based mortar layers This latter operation is considered a conservation intervention in its own right page 86 and should not be undertaken without the guidance and supervision of a conservator Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 23 APPENDIX A LIST OF MATERIALS FOR DOCUMENTATION Drawing board Pencil and eras
33. interpreted to include objects collections architecture and sites It serves the conservation community through scientific research education and training model field projects and the broad dissemination of the results of both its own work and the work of others in the field And in all its endeavors it focuses on the creation and dissemination of knowledge that will benefit professionals and organizations responsible for the conservation of the world s cultural heritage The Institut National du Patrimoine of Tunisia is a governmental and administrative institution with civil and financial autonomy It works under the aegis of the Ministry of Culture and Protection of Heritage The Institute s mission is both scientific and technical and focuses on the inventory study protection and presentation of the cultural archaeological historical human and artistic heritage of Tunisia MOSAIKON is a partnership of four institutions the Getty Conservation Institute the Getty Foundation ICCROM and ICCM The aims of the project are to strengthen the network of professionals concerned with the conservation restoration maintenance and management of mosaic heritage in the southern and eastern Mediterranean region provide training to a variety of individuals involved in mosaics conservation and more generally with the management of archaeological sites and museums with mosaics work with national and international bodies to provide a more favo
34. longer exactly corresponds to the mosaic s current condition due to more extensive lacunae for example It is also important to note the provenance and date of the drawing Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Base photograph Single photograph page 52 A base photograph can be obtained by taking a photograph of the mosaic The entire area of the mosaic being documented must be visible in a single photo If this single photo is digital the image can be rectified later with a computer that is some deformations can be corrected to make the image appears closer to reality using image processing software such as Adobe Photoshop or GIMP Digital photomontage see Supplemental Manual pages 11 22 A montage of digital photographs can be assembled by taking photographs sector by sector of the mosaic with a digital camera Rectifying and then putting these photos together with an image processing software such as Adobe Photoshop or GIMP will produce a complete single image of the entire mosaic Existing photograph A copy of an existing photograph found in a book in an archive or given by the archaeologist or the site director can also be used An existing photograph might have to be modified if it is outdated and no longer exactly corresponds to the mosaic s current condition due for example to more extensive lacunae It is also imp
35. model Subject Mosaic ID Date Number Category Note 10 IDentification 2PI Previous Interventions If two Use the technical files share ite Building iti a 3CA Condition Assessment vocabulary found in the the same indul legends and th ID dat PLanning map legends an e date Illustrated Glossary subject and 5CI Current Interventions format 6WA Work Aid Example DG Th1 11 2 2006 05 10 3CA DetachedTess 04 DG Th1 11 2 2006 05 10 3CA DetachedTess 04 At the end of each intervention campaign on a mosaic or if possible more often the digital files contained in the work computer should be backed up onto compact discs CD or DVD The data pertaining to each room or each building should be burned on a CD or several if necessary and include all the electronic files created during the campaign and all previous campaigns On each CD itself using a permanent marking pen the content the full IDs of the mosaics and the dates of the maintenance campaigns during which the files were created should be written Each CD should be stored in its individual box or in a CD envelope affording long term protection and should then be filed in the folder of the corresponding room or the archive box of the corresponding building It is important to create at least one back up archival copy of the digital files in the event that the computer loses data due to improper handling
36. mortar mixed with ceramic fragments into which quadrangular tesserae or small stone fragments are placed at random in lines or following simple geometric designs When this type of pavement does not include placed tesserae or stone fragments it is called cocciopesto When the pavement is composed of a lime mortar mixed with stone fragments or other material it is simply called a mortar pavement Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 3 MAINTENANCE Mosaics exposed on site can only be preserved through regular maintenance to reduce the impact of destructive environmental forces and being walked on Maintenance consists of a series of operations that includes a preliminary study of the mosaic initial stabilization work and periodic inspection of the mosaic s condition followed by if needed planned interventions to protect and stabilize it Periodic inspection begins with collecting data about the mosaic its condition and the condition of previous interventions This information is needed to assess how urgently interventions are needed to estimate the type and amount of work to be done and to organize the work Once this planning is done remedial stabilization measures can be implemented and protective interventions can begin Each time the condition of a mosaic is inspected a new maintenance cycle begins It is essential to refer t
37. presence of a virus computer material deteriorated by water etc Another copy can be kept in the national heritage archives When the computer memory is full it works much slower In this case all the files should be saved on an external hard drive which will be kept on site to insure the long term conservation of digital images and documents Afterwards the digital files should be deleted from the computer to free up space on the computer s hard drive Using a scanner connected to a computer traditional photographic images negatives slides or prints can also be transformed into digital images which can then be printed Scanning may also be used to create a digital copy of any other documents created on paper Data Forms Maps and Legends to safeguard them in a digital format Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 39 DOCUMENTATION AND ARCHIVING DURING THE MAINTENANCE CYCLES Regular maintenance cycles should follow the initial stabilization intervention of a mosaic and they should include the periodic inspection of the condition of the mosaic and of past interventions as well as the execution of newly needed interventions Figure 3 It is important to inspect the mosaic regularly at least once a year When filling out a new Data Form No 3 Condition Assessment only the deterioration phenomena that have occurred since
38. small amounts of lime should be added to the water each time to limit the effects of the reaction and avoid splashing of boiling water or lime This operation should be carried out in clean containers that are not sensitive to heat plastic containers are generally not appropriate and in an open area When slaking quicklime gloves and protective goggles should be worn Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 07 REBURIAL Reburial is the temporary or permanent re covering of archaeological remains exposed during the excavation of a site It is done by using fill materials and separation layers used alone or in various combinations and in different sequences Figure 26 Reburial is a protective measure designed to ensure the in situ conservation of mosaics Its purpose is to slow down the deterioration of a mosaic by controlling some environmental factors to which an open air mosaic is normally exposed Like a shelter the reburial of a mosaic will protect it against the direct action of the weather In addition it will provide a more stable environment around the mosaic Finally due to its thickness it will protect the mosaic surface from mechanical deterioration caused by people walking on it for example Like any intervention a reburial requires regular maintenance to remain effective A number of elements must be taken into con
39. the 24 mm x 36 mm format of a traditional photographic film Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 65 File type Some cameras can save photographs in two different types of digital files in JPEG or in RAW format The JPEG format is the most appropriate because it is a compressed image format therefore the file size is smaller e File size A digital image is made up of many very small squares called pixels The number of pixels that make up the images can be chosen The more pixels a photographic image has the finer and more defined it will appear on a computer screen or when printed This difference is not visible on the screen of the camera because it is too small However the more pixels an image has the heavier the digital file will be that is the larger its size will be Files that are too heavy can cause problems when they are uploaded in large numbers to a computer or when working on them with software In general for documentation a 3M photograph size M megapixels is appropriate For photographs used to make a photomontage a 1M size or a maximum size of 2M is sufficient e Image recording quality Some cameras offer a choice between different qualities of JPEG images Quality refers to the compression rate of the image The more compressed the image is the less accurate the image will be and the less it ref
40. to the preparatory layers surfaces and to the sides of tesserae To be able to lift a section of the tessellatum and avoid having to disassemble the tesserae one by one facing can be used that is gluing a piece of fabric to the mosaic surface Facing a section of the tessellatum with an adhesive to temporarily lift up together some of the tesserae is considered a specialized conservation treatment operation and should be supervised by a conservator The tools most commonly used for stabilization interventions are spatulas tweezers small rubber bowls for small scale operations trowels mortar buckets for larger scale operations hand Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 05 drills syringes and needles for grouting with liquid mortar Sieves of different sizes are used to prepare the aggregates Water buckets sponges and hand held water sprayers are used to give a good finish to the mortars while wet floor cloths and plastic sheets ensure that the mortars dry slowly A list of materials needed for an intervention campaign is provided in Appendix B page 125 106 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 HEALTH AND SAFETY MEASURES REGARDING LIME Lime is not a toxic product however its prolonged use without protection can be
41. within the same building should be filed together in the same archive box Copies of existing documentation that may have been found i e old photos from the excavation published articles etc and a site plan showing the location of the building in question should also be placed in a building s archive box The archive should be left on site in the care of the site manager and must be stored in a dry cool area away from sunlight A second copy of this documentation can be stored in the national archives Archiving of digital documentation All digital files created during the documentation of a mosaic should be organized on the computer so that they can be easily located now and in the future It will be necessary to create a filing system with digital folders Figure 2 The main folder containing all the information about a Site Mosaic Folder Building B Room 3 Digital photographs Photo layouts Photo montages Base photographs etc Room 4 Room 10 Building D FIGURE2 Digital Filing System 36 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 site should contain a separate folder for each building that has mosaics Each building folder should have a sub folder for each room that has mosaics The room folder should contain all the digital files photos photo layouts photomontages etc pertaining to the mosaic of this room
42. E DRAWING INDIRECTLY FROM A PHOTOGRAPH Equipment Photograph on paper Drawing board e Masking tape Tracing paper Pencil and eraser e 0 1 or 0 2 ultra fine point pen and razor blade Steps Attach the photograph to the drawing board with masking tape Attach in the same manner a sheet of tracing paper over the photograph On the sheet of tracing paper trace the outline of the mosaic its simplified design and the outline of the walls of the room if they are close by with a pencil Overlay a second sheet of tracing paper onto the first one and with a 0 1 or 0 2 ultra fine point pen transfer the drawing onto the second sheet by retracing the outline of the original pencil drawing made on the first tracing paper sheet If a second tracing paper sheet is not available turn the first sheet over and retrace the original drawing with a pen on the reverse side then erase the pencil drawing made on the front of the tracing paper sheet Label the base drawing Figure 4 Base Drawing with the following information ID Mosaic ID Always write the Mosaic ID on the base Base made on Date Always write on the base the date it was made Title Leave empty on the base Date Leave empty on the base Prepared by Leave empty on the base Also add the graphic scale page 58 and an arrow indicating North Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoin
43. S Ie oM M RR top 86 86 mt E 87 SAN RET 89 92 bleed 92 Aggregat 95 Factors influencing the properties of a lime based 96 Mortars for mosaic stabilization interventions eee 100 StabilizatiQn au in ettet ie TERI AED 101 Health and Safety Measures Regarding Lime sss 107 Rebunal meccses eee ere aed 108 Important factors affecting the performance of a 110 Practical considerations acte eee eee dee netos 111 Materials tei 112 Separation membranes eee esistente tente nnttnn ttn 114 sias vanae pain apa RU Rt MCN Dip du E 117 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 6 MAINTENANCE OF MOSAICS RE LAID ON REINFORCED CONCRETE PANELS AND REPLACED IN SITU 119 The different methods and materials which have been used to detach and relay MOSAICS
44. Technician Training for the Maintenance of In Situ Mosaics d 1 Getty Conservation Institute 2 MOSAIKON Institut National du Patrimoine Wes 36 7 e I f lt d in ig ire ait S M duy s tas i c 7 lt Technician Training for the Maintenance of In Situ Mosaics Livia Alberti Elsa Bourguiguon and Thomas Roby The Getty Conservation Institute Los Angeles Institut National du Patrimoine Tunis Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Copyright 2008 2011 2013 J Paul Getty Trust and Institut National du Patrimoine de Tunisie Every effort has been made to contact the copyright holders of the material in this book and to obtain permission to publish it Any omissions will be corrected in future volumes if the publisher is notified in writing Getty Conservation Institute 1200 Getty Center Drive Suite 700 Los Angeles CA 90049 1684 USA Telephone 310 440 7525 Fax 310 440 7702 E mail gciweb getty edu www getty edu conservation Institut National du Patrimoine 4 Place du Chateau 1008 Tunis Tunisia Telephone 216 71 561 622 Fax 216 71 562 452 E mail dginp inp rnrt tn www inp rnrt tn Design Hespenheide Design The Getty Conservation Institute works to advance conservation practice in the visual arts broadly
45. US 2uaudsouny sesne5 sjuabe pue II RWI S1032eJ sesso oJd Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Micro organisms Micro organisms are small living organisms which can be of different colors and shapes Those most commonly found adhering to mosaic surfaces are algae lichens and mosses Algae are generally green or black Algae can grow on the surface of the mosaic and under the tesserae and even inside the tesserae and the mortars Lichens take root directly on the tesserae surface They form a layer which can be of different colors and which can in certain cases entirely cover a mosaic surface Mosses which are small plants take root in damp areas where soil is present for example in the interstices between mosaic tesserae These various micro organisms often cohabit and their presence contributes to keeping the mosaic damp thereby causing the deterioration of its materials and promoting the growth of larger plants Vegetation Grass and plants grow in soil present in the interstices between tesserae cracks and lacunae of a mosaic as well as in the interstices between tesserae Trees shrubs and bushes grow in the soil around the mosaic Plant roots can grow under the mosaic or within it in between
46. ae the note will be shortened to DetachedrTess The note should also serve to indicate whether a file is used as a base photograph For example DG Th1 11 2006 05 15 1ID BasePhoto will be the name for the base photograph of the mosaic DG Th1 11 If the number given by the digital camera to a digital photo has been written on the Photograph Map this number will be kept as the fourth part of the file name without adding a supplementary short descriptive note For example the file name DG Th1 11 2006 05 15 6AT DSC34689 is the digital photo number DSC34689 written on the Photograph Map of the mosaic DG Th1 11 In any case this fourth part of the file name should be kept as short as possible as some computer software does not accept file names longer than 32 characters Part 5 If several files of the same format doc jpg etc have the same ID date and subject category and note part 5 of the file name should be used to number them 01 02 03 etc to insure that each file has a different name At the end of a file name a suffix also called a file extension indicates the file format It is always preceded by a dot It is dictated by the program with which the file was created and it is normally added automatically by the software 38 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Thus a file name should comply with the following
47. aid mosaic Deformed mosaic support panels Bulging areas in support panels Visible deterioration of metal reinforcements in support panels Detachment between tessellatum and support panels Cracks in mosaic support panels PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 23 Data Form No 4 Intervention Planning Data Form No 4 is used to estimate the time and personnel needed to carry out each intervention For each operation a first estimate of the number of work days required for one technician will be calculated The number of work days necessary for a group of technicians to completely stabilize a mosaic is then assessed factoring in the time to organize labor and any other circumstance that might affect the process During this phase the need for a conservator to intervene on the mosaic to solve the most difficult conservation problems will be determined Other types of work on site that may be needed should also be noted such as the construction of a shelter or the creation of a visitors path which requires the intervention of a specialist such as an architect or an engineer This data form must be filled out under the guidance of the site manager 24 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institut
48. aking it easier to recognize the original areas of the mosaic from the areas where materials have been recently added to stabilize it and fill in missing parts The reintegration of a lacuna with tesserae is therefore a stabilization intervention which is strongly discouraged To choose the composition of mortars needed for stabilization it is useful to gather a range of binders and aggregates and to prepare a number of mortar samples They can then be evaluated in the field and if it is also possible in the laboratory with the help of a conservator It is preferable to make samples of each mortar one intends to use When the mortars are chosen their composition mortar formula should be written down specifying for which kind of interventions they will be used For certain conservation problems a conservator should be called upon For example if the preparatory layers of a mosaic or its individual tesserae are too fragile to be stabilized using only lime based treatments a conservator can consolidate the deteriorated constituent materials with other types of products If large tree roots threaten a mosaic a conservator may select an appropriate chemical herbicide etc and supervise its application During stabilization operations it may be required to temporarily lift up a small section of the tessellatum in order for example to remove roots or soil underneath This operation may be necessary so that stabilization mortars adhere well
49. al picks Tweezers Chisels width 3 10 mm Hammers weight 200 500 9 Hand drills and bits 2 2 2 mm Syringes volume 20 50 cc Needles for syringes diameter 1 8 2 2 mm Petroleum jelly Trowels Small dustpans and brushes Flat paint brushes width 2 6 cm Toothbrushes Nailbrushes _____Large brushes Sponges Cotton Colored sticker dots Wooden sticks Rubber manual blower bulbs Small rubber bowls to mix mortar Hand held water sprayers Water buckets Rubber gloves Disposable gloves Small knee pads Sun umbrellas Paper dust masks Goggles Pliers Pincers Screwdrivers Wood and metal saws Nails ______ Sharpening stone and mineral oil _____ cleaner Storage bins for aggregates and binders Plastic pitchers Plastic containers for tesserae Mortar buckets Sieves opening sizes 0 25 mm 0 5 mm and 1to 5 mm Wheelbarrow Mortar mixer Shovels Brooms Floor cloths Plastic sheets String Storage tent for materials Water hose Water cistern Electrical extension cord Generator lime putty Natural hydraulic lime Sands ___Gravels Crushed brick Fine ceramic and stone powders for grouting Woven plastic sheeting
50. ancial resources to conserve on site either exposed or under a shelter all the mosaics that have been uncovered over more than a century Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Xl It is important to realize that mosaic maintenance work is by nature a slow process that must be thorough in order to be effective Technicians should frequently inspect the condition of the mosaic and their previous work and treat it again if necessary so as to prevent new damage as much as possible This painstaking process of mosaic maintenance and their reburial are required to insure the conservation of in situ mosaics for the future XII Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 INTRODUCTION TO THE MAINTENANCE IN SITU MOSAICS A mosaic is a decorative surface finishing technique see Illustrated Glossary pages 1 18 It is made by inserting elements made of hard materials into a soft layer that holds them in place as it sets Mosaics found on archaeological sites are usually made of stone commonly marble limestone or sandstone ceramic or glass elements inserted in a lime based mortar They often embellish the floors of a building but they can also be used on vertical surfaces and vaults Opus tessellatum is the most common type of ancient pa
51. and 2007 as well as today as co author and editor of this latest version of the technician training course for the maintenance of in situ mosaics We would also like to thank Amel Chabbi Bettina Lucherini Francesca Piqu and the interns Christian De Brer and Sebastiaan Godts for their past contributions We express our gratitude to Dana Reemes for his illustrations and his sense of humor that help enliven the text We would like also to thank Debi van Zyl for the additional illustrations present in this latest version And last but not least to the trainees of the four previous courses in Tunisia who have collaborated in this teaching laboratory we thank them for their patience and response to this work in progress Thomas Roby teacher conservator Getty Conservation Institute Livia Alberti consultant teacher conservator Ermanno Carbonara consultant teacher conservator Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 vil FOREWORD Over the course of the last century archaeological excavations have revealed thousands of mosaic pavements from Classical Antiquity from the Punic Hellenistic periods to the Roman and Byzantine periods Mosaics were an integral part of a wide variety of ancient buildings from public bathhouses and churches to private houses and villas Their decorative surfaces of stone and glass tesserae are important
52. artistic evidence that sheds light onto the history religions and aesthetics of the ancient world While excavations have raised public awareness of mosaics they have also removed the soil and rubble that generally protected them for centuries Once re exposed and devoid of the protection provided by ancient walls and roofs mosaic pavements are subjected to a range of destructive environmental forces and detrimental conditions such as rain sun frost ground water pollution and growth of vegetation as well as human neglect and misuse Years of exposure to the environment results in the rapid deterioration and eventual loss of the tesserae surfaces followed by that of the lime mortar foundation layers of the mosaic In the past archaeologists responded to the conservation challenge of excavated mosaics by detaching and lifting the tesserae layer and relaying it on a new support generally panels of reinforced concrete The mosaics were then either exhibited or stored a museum or sometimes re laid in situ or simply left somewhere on site This was the fate of mosaics or parts of mosaics considered of greater importance or significance due to their figurative subject or their intricate geometric design The numerous mosaics of lesser importance and quality were often left in situ without any protection except for occasional cement mortar repairs to fill areas of surface loss In recent decades archaeologists and conservators have increasingly
53. ated should also be taken into consideration Finally a stabilization mortar should also have the properties required for the operation it will be used for resetting tesserae or protecting mosaic edges 100 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 STABILIZATION During maintenance work interventions on in situ mosaics consist mainly in carrying out periodic and programmed stabilization operations using lime based mortars The aim of these interventions is to restore the structural stability of the mosaics and prevent any new deterioration from occurring The main types of interventions requiring mortars are Resetting detached tesserae in their original position and orientation Figure 22 FRESH MORTAR FIGURE22 Resetting detached tesserae Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 101 Filling interstices between tesserae Figure 23 FIGURE23 Filling interstices between tesserae Protecting tessellatum edges Figure 24 e Filling lacunae and cracks Figure 24 SESS E gt NE FIGURE 24 Filling lacunae and edging repairs 102 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Grouting voi
54. be an effective and immediate response to the lack of trained professional conservators or technicians specialized in mosaic conservation However to insure long term effectiveness the new profiles of conservation technician and conservator must be recognized as professions in their own right associated with specific grades within the State administration The training provided during this short course will enable technicians to considerably improve the condition of in situ mosaics and work independently on tasks corresponding to the technical level they have achieved They will however need the supervision of a conservator to help them organize their work and guide them in operations above a certain level of difficulty and complexity Their work is first of all based on the documentation and assessment of the condition of a mosaic followed by interventions using lime mortars to stabilize in situ mosaics Lifting mosaics is not part of their training but the stabilization of already detached mosaics re laid on modern supports is Technicians are taught respect for the work of art and its authenticity and consequently their stabilization work should not be excessive or visually obvious Finally the operation of mosaic reburial is taught because it is the only type of preventive conservation operation that technicians can implement without the help of a specialist Reburial is necessary because there will never be sufficient human and fin
55. being the more ancient Figure 1 illustrates the different ways of labeling the different sections fragments or levels of a mosaic An example of how a Mosaic ID is composed for a mosaic on the site of Utica UT in the building of the Maison de la Cascade MC in room 23 23 and for the third section of the mosaic 3 the Mosaic ID will be UT MC 23 3 Data Form No 1 also contains a space in which to sketch the walls of the room and the outline of the existing mosaic In addition this sketch should include the dimensions of the mosaic or of its different fragments The numbers of the sections and or letters of the fragments should also be recorded in the sketch Data Form No 1 should also come with an overall photograph of the mosaic and a plan of the building showing the location of the room in which the mosaic is situated This form is only filled out once for each mosaic the first time it is documented It must be completed with the person responsible for the site 12 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 KAZ 950 Y XX 21 2 dno 9 n OX ANA is 2013 Tun SECTIONS FRAGMENTS LEVELS fragments or levels of a mosaic FIGURE 1 Labeling the different sections ation Institute Institut National du Patrimoine Getty Conservi of In Situ Mosa
56. build up of binder in some areas than in others If the particles are of different sizes they will distribute themselves so as to fill all the voids good compaction and the thickness of the binder distributed around the particles will be constant A more even distribution of the binder makes the mortar stronger Figure 20 GOOD COMPACTION POOR COMPACTION FIGURE 20 Distribution of aggregate particles Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 97 FIGURE 21 Sieving of aggregates in several fractions Furthermore aggregate size is chosen according to the required thickness of the mortar The thicker the mortar needs to be the larger the aggregates should be To obtain a mortar with a good particle size range different kinds of sands gravels and stone powders can be used and sieved to obtain fractions of different sizes that are mixed in the proper proportions Figure 21 Proportion of water a mortar The amount of water used to prepare a mortar called the mixing water is a factor that influences the properties and performance of a mortar Using a lot of mixing water makes the mortar more malleable but will cause significant shrinkage when the water evaporates causing the mortar to crack Using too little water makes the mortar harder to work and it will adhere poorly In addition this will result in a poor setting of hy
57. burned at high temperature Hydraulic lime can be slightly or strongly hydraulic depending on the type of limestone used and the burning temperature Natural hydraulic lime should be stored in a dry place and be used quickly after its manufacturing date Artificial hydraulic limes and cements powder To make these materials additional products are added to the stone during the manufacturing process The additives give these materials significant hydraulic properties contributing to their great hardness Due to their manufacturing process these materials also contain soluble salts Artificial hydraulic limes and cements should be stored in a dry place For all conservation and maintenance work on in situ mosaics it is strongly advised to use natural lime based mortars lime putty and natural hydraulic lime because their chemical composition and their physical characteristics are similar to those of ancient materials Artificial hydraulic limes and cements are generally too hard and also contain soluble salts that can deteriorate mosaics For the maintenance of mosaics which have been lifted and re laid ona reinforced concrete support white cement based mortars are sometimes used page 119 94 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Aggregates Aggregates make up the skeleton of the mortar their hardness contributes to its strength an
58. ciated roots found on and around the mosaic because the reburial environment is generally favorable to vegetation growth It is imperative to stabilize the most damaged areas and address structural problems that could worsen during the reburial or when the fill is removed In the case of a mosaic re laid on reinforced concrete panels and replaced in situ reburial in the medium as well as in the long term is not recommended Indeed the oxidation of the iron of the panel reinforcements will continue once the mosaic is reburied which will cause an increase in volume of the metal reinforcements and the continuing deterioration of the panel and the tessera layer that it supports In designing a reburial it is always necessary to find a way to contain the fill materials In areas where the walls of the room cannot be used for this purpose wooden planks can be used a dry stone wall without mortar can be built or a wall made of soil or sand filled bags can be made It may become necessary to remove the reburial materials from the surface of a mosaic either because the reburial was designed as a temporary protection or simply to inspect the condition of the mosaic When uncovering a buried mosaic fill materials and separation layers should be carefully and gradually removed one after the other paying particular attention to the removal of materials in direct contact with the mosaic A reburial design will differ depending on the type of p
59. d they help decrease mortar shrinkage during setting A good aggregate should be clean that is should not contain soil dust and especially salts The cleanliness of an aggregate can always be improved by washing it with water Aggregates can be divided in two main categories those that are inert and those that react with the binder to give hydraulic properties to the mortar Inert aggregates Sand and gravel Sands and gravels are inert aggregates because they do not react chemically with binders Sands can come from a riverbed or a quarry They have small size grains Sands from quarries are generally less clean than river sands which have been naturally washed Beach sands should not be used because they contain a lot of salt Gravels come from quarries and are crushed pieces of stone There are many types of sands and gravels of different sizes with different hardness color and particle shape Aggregates giving hydraulic properties to a mortar Fired clay volcanic earths and rocks Bricks tiles or pottery made of fired clay crushed and ground can be used as aggregates and can give hydraulic properties to lime putty mortars The reactivity of these materials with lime depends on the type of original clay and on its firing temperature It is generally considered that if the clay firing temperature is very high the material reactivity will be less significant or even non existent this is the case for a lot of modern bricks
60. d in the memory card of a digital camera Computer Word processing software such as Microsoft Word for example Image processing software such as Adobe Photoshop for example if available Printer and paper sheets in A4 or A3 format Steps Upload the digital photograph from the camera to the computer Check that the image is correctly framed and in focus and rotate it if need be so that it is in the proper orientation see Supplemental Manuals pages 3 6 If an image processing software such as Adobe Photoshop is available use it to rectify the photograph see Supplemental Manuals pages 11 22 Rename the photograph and file it in the digital folder corresponding to the room where the mosaic is following the digital file archiving method page 36 Insert the photograph into a word processing document using a software such as Microsoft Word see Layout of Digital Photographs and label the base photograph with the following information ID Mosaic ID Always write the Mosaic ID on the base Base made on Date Always write on the base the date it was made Title Leave empty on the base Date Leave empty on the base Prepared by Leave empty on the base The base photograph should be printed in color in A4 format or if it is possible and needed in A3 format Add by hand the graphic scale page 58 and an arrow indicating North Figure 5 Base photograph if they are not present within the frame The color print should be kept as t
61. draulic as well as non hydraulic limes Non hydraulic and hydraulic mortars must be kept moist throughout the setting period to insure that the whole mass of mortar sets completely 98 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Liquid mortars also called grouts a particular type of mortar containing a larger amount of water compared to paste mortars The correct amount of water to use should be the smallest amount necessary to make the mortar fluid yet be injectable In any case the amount should not be more than one part of water to one part of binder It is important to use clean water to mix mortar and to it ensure it does not contain salts Color and texture The visual appearance of a mortar due in particular to its color and its surface texture is a result of the selection of the binder and aggregates and of their ratios The binder influences the mortar color through its own color The aggregates influence both the mortar color and surface texture through the color shape and size of their particles For the aggregate particles to contribute to the color of the mortar it is necessary to make them visible by removing a thin layer of binder from the mortar surface with a wet sponge before it sets Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis
62. ds located between the preparatory layers of the mosaic Figure 25 FIGURE 25 Grouting voids between preparatory layers Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 103 Cleaning must be carried out to remove dust soil and micro organisms before any stabilization intervention to ensure that stabilization mortars can adhere properly to the surfaces of preparatory layers and to the sides of the tesserae If the surfaces of preparatory layers inside lacunae are fragile they can be consolidated with lime water before undertaking stabilization operations Each stabilization intervention requires a specific mortar with particular characteristics Depending on the intended use a mortar may require a specific hardness and workability and if the mortar is to be visible a specific color and texture For example to reset detached tesserae the use of a lime rich mortar made of lime putty anda fine aggregate is recommended Lime putty is chosen as a binder because the mortar should have good adhesive properties and be malleable two characteristics of lime putty that are accentuated by the fact that the mortar contains a lot of binder A fine aggregate should be used so that the mortar does not create an additional thickness under the tessera being reset and that it fills the narrow spaces around each tessera A liquid mortar also called
63. during excavations abandonment of mosaics after their excavation and poor management of visitors leading to mosaics being walked on by tourists Inappropriate interventions poorly executed work and use of potentially damaging materials such as cement plaster iron elements and irreversible resins Destruction gratuitous deliberate or accidental due to vandalism wars or the removal of a few souvenir fragments etc Theft of mosaic sections for the purpose of selling them New constructions houses roads etc leading to destruction of part of a site and its mosaics 84 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 INHERENT PROPERTIES OF THE MATERIALS Besides the environment and human activities mosaic deterioration depends on the inherent properties of the materials of a mosaic Each material has unique characteristics such as hardness mineral composition etc In particular all mosaic materials stone mortar ceramic are porous but the amount of water they can absorb depends on the quantity and the structure of their pores Thus two different materials exposed to the same environment will not deteriorate in the same way For example within the same mosaic pavement it can often be observed that tesserae of a certain stone type are much more deteriorated than others Similarly mortars can be more or less resistant W
64. e on the drawing or the photograph For example measure the total length of one side of the mosaic or the distance between two decorative motifs A long enough distance should be selected more than 1 meter if possible Measure the same distance on the drawing or the photograph Divide the distance on drawing by the distance on the mosaic expressing both of them with the same unit of measure centimeters or meters Multiply the result of the division by 100 This final number is the number of centimeters measured on the drawing that correspond to 1 meter on the actual mosaic this will enable the drawing of the graphic scale Draw on the base drawing or photograph a straight line the length of which is the final number of centimeters just obtained by the Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 previous calculation Mark at the ends of this line the values 0 to the left and 1 meter to the right The scale bar can be further subdivided into segments to indicate intermediate measurements Calculation example the actual width of the mosaic is 2 4 m that is 240 cm and the width of the mosaic drawn on paper is 23 cm First divide the width of the mosaic on the paper by its width in reality which is 23 240 0 095 Then multiply the result by 100 which is 0 095 x 100 9 5 This means that 9 5 cm measured on the drawing are equal to 1 me
65. e Tunis 2013 51 MAKING A BASE PHOTOGRAPH FROM A SINGLE PHOTOGRAPH Single photograph Equipment Soft brush Digital camera Stepladder short ladder or other prop to take pictures from above Metric photo scale Small chalkboard and white chalk Compass Photograph Log and pen Steps Remove dirt and sand from the mosaic surface with a soft brush if it is possible to do so without damaging it Place within the image frame of the photograph but outside the mosaic surface the metric photo scale and the chalkboard where the mosaic ID and the date are written Indicate North on the chalkboard or with an arrow next to it Adjust the zoom lens of the camera page 62 so that the entire mosaic the metric photo scale and the chalkboard are visible in the photo frame To minimize subject deformation the photograph should be taken from an elevated position as vertically as possible from the center of the mosaic by using a stepladder or a short ladder or other prop If the camera is used in manual mode adjust also the shutter speed and the lens aperture so that every area of the image is in focus page 67 Take the photograph and add the information concerning it on the Photograph Log page 33 52 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Base photograph from a single photograph Equipment Photograph store
66. e Institut National du Patrimoine Tunis 2013 DATA FORM NO 4 INTERVENTION PLANNING PLANNING PHASE This form must be completed with the site manager TIME REQUIRED FOR ORGANIZATION AND COMPLETION OF THE WORK Vegetation removal Notes Cleaning Notes Removal of modern repair mortars Notes Resetting tesserae Notes Filling interstices between tesserae Notes Grouting voids between preparatory layers Notes Infilling lacunae and edging repairs Notes Removal and resetting tesserae with facing Notes Removal or treatment of support metal reinforcements Notes Drainage Notes Reburial Notes Documentation Notes Material preparation Notes L Other Notes TOTAL WORK DAYS FOR 1 TECHNICIAN Number of days weeks months Intervention by a specialist needed on or around the mosaic Notes PREPARED BY work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician work days for 1 technician for number of technicians Technician Training for the Maintenance of In Situ Mosaics Getty Co
67. e Institut National du Patrimoine Tunis 2013 a basic training in this field These teaching materials were designed for the trainees average level of education which generally was below or just at high school level and were revised during the four training courses carried out in Tunisia between 2001 and 2008 The 2011 version was created within the framework of the MOSAIKON Project for the first technician course for North African countries Due to the rapid transition to digital photography and the rising number of computer savvy trainees this latest version provides a detailed presentation of the use of digital photography for documentation It also refers to new supporting documents which will be provided during the course to assist the training using this technology The maintenance of detached mosaics re laid on reinforced concrete panels has also been taken into consideration in the 2011 version This collection of training material was produced to be used by mosaic maintenance technicians during and after a short course combining several training sessions on site and independent practical exercises between sessions The training is part of the broader MOSAIKON Project a regional initiative which aims to strengthen the capacities of national authorities responsible for archaeological sites to better care for the large number of in situ mosaics located in their country Training personnel already employed on sites with mosaics seemed to
68. e is the first step in graphic documentation Copies of the base or transparent sheets superimposed onto the base are used to make all the maps There are two types of bases Base drawing Base photograph A base drawing is a drawing of the mosaic A base photograph is a photograph of the mosaic Each type of base can be obtained through different techniques Table 1 42 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 sdew SUOIUSAI9 U JUIN sdew juauussassy uonipuo5 sdeuJ SNOIAAd sdew jo sed aseq y uo A ueJedsueg e 10 Jaded sjaaus aseq y Jo seido o1oud umep sdew 993 UO eipew JO YOO 21 y Jo ydesBojoud e jo Adod 1 ay uo 25991 e ayew pue YUM 5101295 Aq 21 y y Jo ajbuls 9AIUDJe JO 3IesouJ y Ado y uo 10 y UO 19945 y MeJp pue 5101295 q 10 awed e ul 2 5 y
69. e mosaic one sector after another following the previously established divisions always keeping the camera at the same distance from the mosaic surface from one photograph to the next To minimize subject deformation the photograph should be taken from an elevated position as vertically as possible from the center of the sector to be photographed However image deformation can be corrected on a computer after shooting using an image processing software such as Adobe Photoshop see Supplemental Manuals pages 11 22 List the photographs on the Photograph Log as they are taken carefully noting the letter number code of the photographed sector 56 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Base photograph from a photographic montage Equipment Photographs stored in the memory card of a digital camera Computer Word processing software such as Microsoft Word for example e mage processing software such as Adobe Photoshop for example if available Printer and paper sheets in A4 or A3 format Steps Upload the digital photographs from the camera to the computer and file them in a new folder within the folder named for the room where the mosaic is located Rename the photographs using for the note part of their name the letter number code of the photographed sector corresponding to the schematic drawing of the mosaic see Su
70. e surface Cleaning of part of the surface Removal of modern repair mortars Resetting tesserae Filling interstices between tesserae Grouting voids between preparatory layers Infilling lacunae and or edging repairs Removal and resetting tesserae with facing Removal of metal reinforcements in support panels Treatment of metal reinforcements in support panels Drainage total thickness and the thickness of each layer Reburial Draw a vertical section of the reburial describe the fill materials and separation membranes used provide the INTERVENTIONS CARRIED OUT AROUND THE MOSAIC Wall stabilization Notes Other Notes NAMES OF THE TECHNICIANS WHO CARRIED OUT THE WORK PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 27 LEGEND CURRENT INTERVENTIONS MOSAIC ID Vegetation removal Cleaning of part of the surface Resetting tesserae Mortar composition Filling interstices between tesserae Mortar composition Grouting voids between preparatory layers Mortar composition Infilling of lacunae and or edging repair Mortar composition Infilling of lacunae and or edging repair Mortar composition Infilling of lacunae and or edging repair
71. e used to record a narrower field of view or to obtain close up images normal lenses or telephoto lenses are used A zoom is a lens that has a field of view which can be changed allowing one to obtain different framings with the same lens ranging from a wide field of view to a narrow field of view that brings the objects photographed closer Some cameras have a fixed lens that cannot be separated from the body others have an interchangeable lens 62 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Before taking a photograph a number of settings must be adjusted on the camera Automatic cameras automatically adjust one or more functions while on manual cameras these settings are adjusted by the photographer Modern good quality cameras usually have both a manual and an automatic mode So called compact cameras are generally smaller cameras with a fixed lens often a zoom the operation of which is often completely automatic So called reflex cameras are generally larger cameras with interchangeable lens which allow manual adjustment of many settings Figure 8 POWER BUTTON MODE DIAL SHUTTER BUTTON VIEWFINDER LENS CAMERA BODY FOCUS ZOOM FIGURE8 Reflex camera Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 63 In view of
72. elens aperture is related to the size of the hole that lets the light enter and reach the sensor when a picture is taken The value of the aperture controls the depth of field that is the size of the sharpness zone This is the distance between the closest point and the furthest point in reality which are both sharp in the photograph The size of the aperture is given by the letter f followed by a number The smaller the aperture is corresponding to a high f such as f 22 the greater the depth of field will be The larger the aperture is corresponding to a small f such as f 2 8 the smaller the depth of field will be If one wants to photograph an entire floor mosaic in a single image page 52 it is strongly recommended that an aperture as small as possible corresponding to a high f is used so that the entire mosaic surface is in focus When all adjustments have been made the shutter button is pressed completely to take a photograph General advice about photography To take a good photograph one should consider a number of practical aspects Avoid taking photographs facing the sun Avoid taking photographs of areas that are partly shaded and partly lit as too great a difference in lighting will not allow the camera to be correctly adjusted for both areas at the same time Consequently part of the photograph will be too light or too dark Payattention to how you frame the image It should be centered exactly on the a
73. en inserted into the main computer case A CD ROM drive can read information contained in CDs but can also often write burn CDs to store data outside of the computer Today virtually every computer also contains a modem that can communicate with other computers remotely via a telephone line It is the modem that enables the user to connect to the Internet either by plugging a cable to the computer or by wireless technology like Bluetooth or WiFi Many other specialized peripheral devices can be connected to a computer always plugged into the CPU to do specific tasks For example a USB memory key or portable hard drive is used to store computer data outside the computer A printer is used to make paper copies of digital documents and images A scanner is used to create digital documents from real documents such as a print photograph a map drawn with colored pencils or a data form completed by hand A digital camera can be plugged into a computer to transfer the photographs from the camera to the hard disk of the computer For a computer to work software needs to be installed on the hard drive A software is a set of computer programs and data that will tell the computer what to do and how to do it There are two broad categories of software system software and application software 72 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 A syste
74. ept with its corresponding map or be drawn on the map itself as a map cannot be understood without a legend Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 61 CHAPTER 3 THE USE OF A CAMERA AND COMPUTER IN DOCUMENTATION CAMERA A camera consists of a body and a lens The light coming from the photographed object enters the camera body through the lens Inside the body a light sensitive surface captures and records this light There are several types of photography which can be differentiated by the nature of the light sensitive surface used Traditional photography uses photographic film digital photography uses an electronic sensor Nowadays traditional cameras are used less and less frequently as it is becoming harder to find film and to develop it Digital cameras also enable the user to print his her own photographs using a computer and a printer Digital photographs can also be displayed on the camera screen immediately enabling the user to view them immediately The camera lens is made of a system of lenses that directs the light inside the camera body changes the amount of light reaching the sensitive surface and adjusts the focus of the image The lens system also determines the framing or field of view that is the limits of the visual field recorded by the camera To record a wider field of view so called wide angle lenses ar
75. er Pencil sharpener Ball point pens 0 1 or 0 2 black ink ultra fine point pen Razor blade Felt pens and colored pencils Permanent markers for writing on plastic transparent sheets White liquid paper correction fluid Rulers and triangles Masking tape A4 and A3 plain paper A4 and A3 graph paper A4 and A3 tracing paper A4 and A3 plastic transparent sheets Colored sticker dots Data Forms Photocopies blank copies of the base drawing or photograph Archive box Folders Binders Plastic sheet protectors A3 portfolio Paper clips Transparent Scotch tape Scissors Stapler and staples pads Soft brush String Equipment to keep the string taut nails wooden planks stones etc Large wooden framing squares 2 meter folding ruler 5 meter retractable measuring tape 20 meter reel measuring tape Digital camera Memory card Photograph Log Stepladder or short ladder Small chalkboard White chalk 124 Black and white metric scale Arrow to indicate North Compass Computer Printer Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 APPENDIX LIST OF MATERIALS FOR AN INTERVENTION CAMPAIGN Tool box Scalpels with interchangeable blades Scalpel blades Scalpels with fixed blade Spatulas Dental spatulas Dent
76. er that can sometimes seep into the ground Inland sites generally experience more significant temperature variations between seasons with hot summers and cold winters and sometimes snow in the mountains Sites close to the desert undergo large temperature differences between very hot days and cold nights Much of the deterioration caused by environmental factors is linked to the presence of water which may derive from e Atmospheric precipitations rain snow etc Condensation water vapor present in humid air is transformed into liquid water when it comes in contact with a surface colder than the air such as the surface of a mosaic Figure 13 HUMID AIR Ei a WET MOSAIC 8 LJ L n ANTA m Am od M ERAN 7 ii f ae Mtt fi 7 DPA CE ZZ FIGURE 13 Condensation when the surface is cooler than the air 78 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Capillary rise water in the soil rises to the surface of a mosaic where it evaporates in the drier air This water can come from the rain that saturates the soil or from a water table close to the soil surface This water movement occurs continuously but when a mosaic is exposed to air after being excavated the water that evaporated at the ground level above the mosaic now evaporates at the m
77. er this first intervention The whole conservation process should be accurately documented in detail In the past conservation treatments often consisted in lifting mosaics and transferring them onto a new support However these operations should only be carried out in exceptional cases where the mosaic would be immediately lost if it were not lifted and transferred Currently it is considered much more appropriate to leave mosaics in situ in their architectural context Maintenance The purpose of maintenance interventions is to preserve the structural integrity of the mosaic over a long period of time after its conservation treatment or initial stabilization intervention carried out by technicians page 101 These interventions are planned when necessary on the basis of regular inspections to check the condition of the mosaic and of the previous interventions They include Operations to prevent the progression of mosaic deterioration by controlling its causes for example regular weeding of the mosaic surface elimination of accumulated water sand and soil and improvement of drainage in the room containing the mosaic Cleaning and localized stabilization of the mosaic in areas where new deterioration has appeared since the last maintenance campaign e Replacement of modern repair mortars that are no longer effective or are damaged Reburial maintenance page 108 repairs of protective shelters and other interventions ca
78. especially if it was placed too close to the tesserae layer Reinforced concrete panels are also sometimes subject to deformation over their entire thickness resulting in a concave panel with uplift of its edges While the cause of this panel bowing is not clear it leads to the separation of panels from each other tessellatum detachment and loss of tesserae The authenticity and strength of mosaics re laid on reinforced concrete panels are already seriously compromised by this previous restoration intervention Once deteriorated these mosaics are particularly problematic to conserve and there are still no real long term solutions Their deterioration can be slowed down by modifying their immediate surroundings For example a mosaic can be protected by a shelter or kept away from sources of moisture The reburial of a mosaic on a reinforced concrete panel will provide a more stable environment but in the long term good results will not be obtained due to the continuing presence of moisture and consequent on going corrosion of the steel bars It is also possible to intervene in a localized manner while keeping the mosaic panels in situ However the treatment of reinforced concrete panels on site without moving them to a conservation workshop is generally difficult to carry out and such interventions cannot be considered a long term solution for the conservation of deteriorated mosaic panels The following section provides a basic description of
79. f the base drawing or photograph using color pencils or felt pens Drawing on a transparent sheet overlaid onto the base The information about the mosaic is recorded on a sheet of tracing paper or of transparency film placed over the base using appropriate pens or pencils The maps directly drawn on a copy of the base will be much more readable if a base drawing is used but they will be more precise if a base photograph is used Generally it is preferable to draw the maps directly on a copy of the base rather than on a transparent sheet 46 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Legends To be read each map must have a legend A legend is an explanatory list of the colors and graphic symbols used to draw the data recorded on the map For example the color red can be used to represent detached tesserae while green hatching can be used to record the presence of micro organisms A legend is established prior to recording data on the map If the legend is on a separate sheet it must always be attached to the map as a reference in the future The legend can also be placed on the edges of the map itself if there is enough space available to list all the information recorded on the map It is advisable to always use the same legend for each type of map condition assessment maps for example to facilitate the comparison between the maps of
80. g of the area to remove debris Treatment of other adjacent bars that are visible but left in situ Filling of the void left by the removed bar and concrete debris e Replacing the tessellatum section previously removed Removal of the facing including all of the adhesive e Filling of the joints cracks and lacunae Complete documentation of the intervention 122 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Such an operation is quite delicate especially if it requires the lifting of a tessellatum section to uncover the steel bars located inside the panel when tesserae located above the corroded bars are still present In this case to limit the risks of the operation the tessellatum is faced with gauze or light cotton fabric over an area that contains both the section to be lifted and an area of the mosaic immediately adjacent to it that will not be lifted In this way the tessellatum can be held together intact during the operation while allowing the damaged section to be opened like a book without removing it entirely The glue used should have the ability to adhere well to the tesserae in order to hold them together during the lifting of the tessellatum section but it must also be easily removed at the end of the intervention Adhesives commonly used for this operation are vinyl resin emulsions acrylic resin solutions or animal
81. grout containing very fine aggregates should be used to fill a void between the mosaic preparatory layers by injection using a syringe Hydraulic lime should be used as a binder because the mortar must be able to set despite a very limited contact with air To fill a very deep lacuna either a hydraulic mortar applied in one layer or a non hydraulic mortar applied in several layers can be used The thicker the mortar layer needs to be the larger the aggregates should be to improve strength and to diminish shrinkage and cracking of the mortar To make a surface fill of a lacuna that will be exposed to the weather and walked on a hydraulic mortar should be used because it is harder and more resistant As with any surface mortar that will remain visible aggregates of the appropriate color and size should be chosen carefully because attention should not be drawn to the intervention mortars when looking at the mosaic The color and texture of the mortar should therefore blend in visually with those of the mosaic so that the mosaic surface always remains visually dominant 104 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 To achieve less evident repairs during Antiquity and in the last century lacunae were sometimes filled with ancient tesserae set in a new bedding mortar Today it is considered more appropriate to emphasize the original pavement by m
82. hazardous Hand protection Lime in its different forms as putty powder in a mortar or dissolved in water dries the skin Extended skin exposure to lime can cause skin lesions that can become deep It is therefore necessary to protect one s hands by wearing rubber gloves during all operations using lime Respiratory tract protection Airborne dust blowing around during the handling and sieving of lime based powder materials is harmful to the lungs It causes respiratory tract irritations and over a long period of time accumulates in the body which can only eliminate a small fraction of it It is therefore necessary to wear a paper dust mask during all these operations Eye protection If lime gets in contact with the eyes it causes strong burning The eyes should be thoroughly rinsed with clear water immediately and at length at least a quarter of an hour In case of a prolonged irritation one should see a doctor It is therefore necessary to wear protective goggles during the operations when there may be projections of lime Safety measures to be taken when slaking quicklime Mixing water and quicklime during slaking causes a chemical reaction that produces heat bringing the water quickly to a boil The reaction can be more or less violent depending on the quality and purity of the quicklime its past exposure to humidity and whether it is in the form of stones or powder Great care must be taken when slaking quicklime and only
83. he original base for eventual photocopying in black and white to make the maps It is also possible to directly print bases from the computer in black and white for the maps If a computer linked to a printer is not available it is possible to print the photograph directly from the camera in a specialized shop In this case all the information detailed above should be written with a pen to complete the base photograph Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 53 MAKING A BASE PHOTOGRAPH FROM A PHOTOGRAPHIC MONTAGE Photographic survey to make the photographic montage Equipment Soft brush Folding ruler retractable measuring tape reel measuring tape Large wooden framing squares to check right angles when setting up the grid Colored sticker dots Digital camera Stepladder short ladder or other prop to take pictures from above Metric photo scale Small chalkboard and white chalk Compass e Photograph Log and pen Sheet of paper pencil and eraser Steps Figure 5 Remove dirt and sand from the mosaic surface with a soft brush if it is possible to do so without damaging it Divide the entire mosaic surface in square sectors of identical size using the measuring tape and the wooden framing square marking the sector angles with colored sticker dots on the surface of the mosaic The size of the sector
84. ics ing for the Maintenance Train Technician Data Form 2 Previous Interventions Data Form No 2 contains information related to maintenance restoration and protection operations carried out on and around the mosaic in the past These previous interventions can date from Antiquity or can be modern Data Form No 2 is accompanied by separate graphic documentation in the form of a map with its legend Previous Interventions Map Areas where different interventions were completed in the past on or around the mosaic are indicated on this map using different colors or symbols If there is not enough room on the legend sheet to describe all the existing previous interventions an Additional Sheet should be used for the legend page 17 Data Form No 2 Previous Interventions is completed and the Previous Interventions Map is created during the initial intervention It may be necessary to redo them at the beginning of the maintenance cycle if old mortars have been replaced during this first intervention 14 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 DATA FORM NO 2 PREVIOUS INTERVENTIONS STUDY PHASE MOSAIC ID PREVIOUS INTERVENTIONS ON THE MOSAIC Mortar repairs Infilling of lacunae Edging repair Filling of interstices between tesserae Grouting of voids between preparatory layers Rei
85. ifting process In most cases the mosaic is subject to many mechanical stresses during this operation It is also normally divided into sections which often leads to the loss of a large quantity of tesserae along the cutting lines Finally after being separated from its original mortar layers which are usually then lost irrevocably the operation of relaying the mosaic on a new support inevitably increases the tessellatum surface area and flattens its surface resulting in a loss of authenticity of its appearance The new support of the re laid tessellatum is usually divided into several panels that are reassembled in situ or in a museum The joints between panels are then filled with tesserae or only mortar Sometimes however mosaics are lifted without being immediately re laid on a new support They can remain for years or decades in this condition with only the tesserae glued to canvas Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 11 9 which makes them very vulnerable and exposes them to irreversible damage due to the loss of tesserae 120 The new supports most commonly used to relay a lifted mosaic are Panels of plaster of Paris reinforced with hemp canvas mounted on a wooden frame This type of support has been used in the past especially during the first half of the 20th century but it is still sometimes used today The panel
86. ill dirty the mosaic surface while tiff can create concretions on it Specialized synthetic materials expanded clay pellets Leca beads or sheets of expanded polystyrene These materials are generally chosen because they are lightweight making them easy to use and because of their insulating properties However they do not allow good transport of liquid water nor maintain stable moisture levels They are expensive and not easily available Some natural materials of volcanic origin such as grains of tuff or pumice which have characteristics similar to synthetic materials are sometimes used as fill material as well Separation membranes The most commonly used separation membranes are plastic sheets plastic netting woven plastic sheets used to make storage bags and other synthetic fabrics such as geotextiles Each has its own advantages and disadvantages and its positive and negative impact on the mosaic Table 4 Plastic sheets It is strongly recommended not to use plastic sheeting because it will stop any liquid water water vapor transport The water trapped under the plastic sheet will foster vegetation growth However plastic sheets are efficient in separating fill materials from each other and from the mosaic They are readily available and inexpensive 114 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013
87. images that have been created during the documentation process 74 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 PART Il DETERIORATION AND INTERVENTIONS Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 4 DETERIORATION The deterioration of a mosaic is the process of transformation that leads to the gradual loss of the original qualities and properties of the constituent materials of a mosaic and the separation of its components tesserae mortars The visible deterioration phenomena produced by these transformations are many and can be classified into different types These phenomena can affect the structure of the mosaic its surface as well as the conservation interventions which were carried out on the mosaic in the past These phenomena are those recorded on Data Form No 3 Condition Assessment and on the four condition assessment maps during the documentation of a mosaic pages 19 23 and see Illustrated Glossary pages 33 52 The causes of deterioration of an in situ mosaic are numerous and several causes are often associated with one type of deterioration Deterioration of a mosaic is generally due to two main categories of factors those related to the environment especially due to the presence of water and those
88. in situ stabilization treatments for reinforced concrete panels Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 21 IN SITU MAINTENANCE TREATMENTS OF MOSAICS RE LAID ON REINFORCED CONCRETE PANELS The in situ treatment of a deteriorated re laid mosaic panel is an intervention that only aims to stabilize areas where the corrosion of steel bars is already well advanced and where the tessellatum is already detached from the panel It does not try to resolve the general problem of the bar corrosion by treating the entire panel or by removing the causes of this corrosion The procedure involves the removal of part or if possible the totality of the steel bar that is causing the damage working from the upper surface of the mosaic panel It should be noted that as the corroded bar is removed from the panel it will become more fragile losing the structural unity provided by the metal reinforcements Consequently the concrete panel will become more and more susceptible to structural fracturing The treatment is generally performed by carrying out the following steps Complete cleaning of the area of the mosaic panel subject to deterioration from a corroded steel bar e Facing of the area Temporary removal of the section of the tessellatum located above the corroded bar if tesserae are still present Removal of the bar remains and cleanin
89. ind film and to have it developed Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 31 At the time the photographs are taken it is strongly recommended that the Photograph Log be filled in in order to remember the subject and the reason for taking the photos once they are uploaded to the computer In the column Digital file No of the Photograph Log the digital photo number given by the camera should be copied page 64 For each photo taken the ID of the photographed mosaic the date and category of the photo and a note about its subject should also be recorded in the Photograph Log pages 37 39 When the photographs are transferred from the camera to the computer the Photograph Log will be used to rename and archive them correctly see Supplemental Manuals for Digital Photographic Documentation pages 3 6 The Photograph Log can then be disposed of To be able to identify the photographed mosaic and its orientation on the photographs a small chalkboard on which is written the ID of the mosaic the date the photo was taken and the direction North should be present within the frame of each photo Detail photographs can document specific aspects or be used as a tool or working aid during some stabilization phases In this case a Photograph Map should be made to make it easier to find again the position of these details on the mo
90. ions and their dimensions will be noted on the sketch of the mosaic on Data Form No 1 Identification Each section will be numbered in succession 1 2 3 4 etc Overlay a second sheet of tracing paper onto the first one with the original pencil drawing and with a 0 1 or 0 2 ultra fine point pen transfer the drawing onto the second sheet by retracing the outline made on the first tracing paper sheet If a second sheet of tracing paper is not available turn over the first sheet and retrace the original drawing with a pen on the reverse side then erase the pencil drawing on the front of the tracing paper sheet During the study phase the grid can be left in place on the mosaic to help draw the maps If one wishes to remove the grid it is advisable beforehand to place color sticker dots on the mosaic surface where the strings intersect and to mark the same points on the drawing base to create reference points Label the base drawing Figure 4 Base Drawing with the following information ID Mosaic ID Always write the Mosaic ID on the base Base made on Date Always write on the base the date it was made Title Leave empty on the base Date Leave empty on the base Prepared by Leave empty on the base Also add the graphic scale page 58 and an arrow indicating North 50 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 MAKING A BAS
91. it is inserted This type of mosaic was also made as a portable work of art independent from any building When the tesserae are rectangular and the same size and arranged in a way to create the impression of a basket weave pattern as with opus figlinum page 3 but they are made of materials other than ceramic the pavement generally considered as a type of opus tessellatum is referred to as pseudo figlinum Apart from opus tessellatum there are other types of ancient mosaics with similar preparatory layers Some of the most common are Opus scutulatum is composed of a usually monochrome opus tessellatum background into which fragments of stone slabs of different colors and of generally irregular shapes are inserted Opus sectile is made of stone slabs most often different colored marble cut with a saw into regular shapes and often placed side by side to create a geometric or figurative design 2 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Opus figlinum is usually made of ceramic fragments of the same size and of rectangular shape inserted along their broken edges The fragments are assembled in groups of a few tesserae 2 to 4 which are placed side by side to create the impression of a basket weave pattern When ceramic elements are arranged in a herringbone pattern it is called opus spicatum Opus signinum is made of a lime
92. ite copy of the base It is easier to work on a black and white base consequently a photocopy of the base printed in color should be made or the base should be directly printed in black and white Write the following information on each copy of the base or each transparent sheet overlaid onto the base filling out the captions left blank on the base 60 The title of the map for example Current Interventions Map The date when the map was drawn for example May 2004 The names of the people who created the map Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Inthe case of a transparent sheet it should be identifiable without the base The words ID Title Date Prepared by which are on the base should be rewritten onto the transparent sheet and most importantly the complete mosaic ID must be included Draw the map on a copy of the base or on a transparent sheet placed over the base using different colors and graphic symbols already defined in the legend When creating the study phase maps Previous Interventions Map and Condition Assessment Maps draw one type of data for the entire mosaic surface before proceeding to the next type of data For the Current Interventions Map it is recommended to record on the map all work as soon as it is completed at the end of each workday A legend must always be k
93. ithin the same building some mosaics can be made with well made mortars which are still in good condition while other mortars are much more deteriorated Although the possible causes of in situ mosaic deterioration are numerous some of which are described above it is important to identify which ones have the greatest impact on a given mosaic With this approach it should be possible with the site manager s agreement to take measures to eliminate these causes to the greatest extent possible thus avoiding future deterioration rather than carrying out periodic repairs on a mosaic that continues to deteriorate Because of the frequent inspections they perform maintenance technicians are perhaps in the best position to identify the primary causes of deterioration and then develop a protection and stabilization program with the help of others Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 85 5 INTERVENTIONS LEVELS OF CONSERVATION TREATMENT Conservation treatments can be divided in three categories according to the aims pursued and the degree of intervention First aid or emergency care The purpose of first aid treatments is only to stabilize the areas of the mosaic in danger of immediate loss pending intervention within the framework of a full treatment program They generally include operations to temporarily protect
94. its layers even if it does not contain soil They can then crack the layers and also cause their detachment Animals Animals like large plants can also provoke structural deteriorations Ants and other insects build their nests rats moles and other small animals dig tunnels within or under the mosaic Sheep cows and other large animals deteriorate the mosaic by walking on it and by pulling out plants that are rooted in or close to the mosaic Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 83 Natural Disasters Exceptional events such as earthquakes or violent floods can also cause the sudden deterioration and loss of mosaics Table 2 Pollution Air and water pollution is also an environmental factor affecting the deterioration of mosaics Table 2 Some chemicals from factories or agricultural fertilizers are dissolved in rainwater and soil moisture These substances may cause deterioration if in contact with the mosaic In particular polluting substances can deteriorate or chemically alter calcareous materials lime mortars limestone and marble HUMAN ACTIVITIES Human activities are also a significant cause of mosaic deterioration Table 2 Among these activities are Poor management of archaeological sites lack of a conservation and maintenance program poor planning of conservation interventions and documentation
95. lects the reality of what is seen but the digital file will be smaller For mosaic documentation it is sufficient to choose the medium image quality among those proposed by the camera White balance This feature enables one to correct the effects of ambient lighting so that the white color is reproduced as realistically as possible without for example reddish or bluish effects When taking photographs under natural daylight in the outdoors the automatic mode is appropriate It corresponds to the setting AWB Automatic White Balance Sensor s sensitivity to light The sensitivity of the sensor is measured in ISO Low ISO settings ISO 100 for example produce sharper images but require more light because the sensitivity is lower High ISO settings ISO 6400 for example allow one to take a picture with less light because the sensitivity is higher but the image will be grainier When taking photographs outdoors the sensitivity can be set to automatic mode AUTO The general settings explained above should be applied to all the photographs taken In addition before taking each picture the following adjustments should be made framing to get the desired field of view focus of the subject to get a sharp image 66 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 shutter speed to change the amount of light entering the camera when a pho
96. m software such as the operating system of the computer controls the basic functions of the computer and manages its use with application softwares Without an operating system like Windows Vista 7 Linux or Mac OS application softwares cannot work An operating system is like the head of a construction site who tells the workers application softwares what to do decides in what order things are done and remembers what has already been done and what remains to be done He decides which worker has the right to use what tools and when and he tells the workers what the person using the computer wants them to do etc An application software is a program that allows the user to do specific tasks A very common application software is a word processing software for example Microsoft Word OpenOffice Writer It can write edit format and save documents that contain text letters reports etc There are many softwares that allow the user to do specific tasks edit an image for example Adobe Photoshop GIMP surf the Internet for example Microsoft Internet Explorer Mozilla Firefox Google Chrome Apple Safari draw a plan do calculations etc When a computer is turned on the desktop appears on the monitor The desktop is the presentation screen of the computer It is made of a large window where there are several icons small pictures which enable one to directly access by clicking on them some software or files Each
97. me based treatment mortars adhere to the original materials Cleaning should be carried out gradually starting with the removal of less strongly adhering deposits like soil before proceeding to more strongly adhering deposits such as micro organisms lichens etc Chemicals should not be used for cleaning as they can damage mosaics Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 89 Cleaning can be carried out with or without water Figures 17 and 18 During cleaning water should be used in minimal amounts and changed as soon as it becomes dirty The most commonly used cleaning tools are scalpels dental tools wooden sticks chisels various kinds of brushes never metal brushes paintbrushes manual blower bulbs vacuum cleaners sponges and hand held water sprayers Each tool has specific characteristics and must therefore be used for specific operations The incorrect use of a tool can damage the mosaic and break the tool Cleaning operations carried out only for aesthetic purposes are considered beyond the scope of maintenance activities 90 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 FIGURE 17 Cleaning without water FIGURE 18 Cleaning with water Technician Training for the Maintenance of In Situ Mosaics Getty Conservation
98. micro organisms and must be difficult for roots to penetrate Furthermore materials should preferably impede insects or other animals from digging tunnels and holes and building nests Durability of materials over time Preferably fill materials should not deteriorate rapidly so that they do not damage the mosaic and they continue to fulfill their function For example metallic netting buried just above the mosaic surface will rust and stain the mosaic Many plastic materials will deteriorate quickly if exposed to the sun Natural fibers such as cotton decompose in humid conditions and in the presence of micro organisms 110 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Finally it is important that all reburial materials remain in place on the mosaic i e that they are not easily dispersed by rain wind etc Effective and sustainable means should therefore be used to keep the reburial fills in place Practical considerations Maintenance requirements Reburials should be maintained regularly Some materials require more time and work to be maintained in good condition For example soil allows plants to grow more easily and will require regular weeding It is also easily eroded by rain and wind Accessibility It is also important to consider the ease of moving and manipulating the materials For temporary reburials in particular it i
99. n Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 pue Ayyiqeys pue ainysiow 100d JO eui silqiuu Asea uea KyAnoe pue 0 euoud ssa 218 eua KqsAJod 4D281 D 1 pezijer eds aens DIESOW Y UO suongJ2u02 ULD H1 104 aayMAJana ajqeyieae JON DJESOW JY 21 au S MA BUOJ 559 n 104 JO e e d 19y pue aJnisiouJ e qe1s surejurelw 31005 1 SMO v 212 bupjozzod enjeu 19910 Ayyiqeys pue 100g JO aui 53191 pue Ajilpeay aAOWA 0 se3 KyAn e jewjue pue y mo16 euoud ssa 5 5 JO aui 51 1
100. ng the focus ring which is located on the part of the lens farthest away from the camera body until the subject seen through the viewfinder or the camera screen is sharp The shutter speed and the lens aperture are two settings that are linked and they allow one to adjust the exposure A good exposure is obtained through a proper combination of shutter speed and lens aperture Many cameras adjust the exposure semi automatically The photographer chooses one setting either the shutter speed mode Shutter Priority or the lens aperture mode Aperture Priority Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 67 and the camera adjusts the other automatically to get the correct exposure In fully manual mode the photographer adjusts both the speed and the aperture The shutter speed is related to the length of time during which the camera s sensor is exposed to light The duration of the exposure is counted in seconds A short duration will be a few fractions of a second less than one second a long duration will be several seconds A shutter speed of 1 60 or 1 125 of a second is recommended Shutter speeds slower than 1 60 of a second that is numbers smaller than 60 in the denominator should not be used without a tripod because it is not possible to keep a hand held camera stable for the time required to obtain a sharp picture Th
101. ning for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 PHOTOGRAPHIC DOCUMENTATION During the study and intervention phases photographic documentation is carried out to record the condition of the mosaic before and after the work and to illustrate certain details Photography also helps to document a mosaic in a more direct and realistic way during the phases of maintenance work It is well suited to illustrating certain conditions such as the seriousness of some types of damage however other types of information can only be represented graphically because they are not visible For example the extent to which micro organisms are present can be documented using a photograph while detachment between preparatory layers can only be represented using graphic documentation Photography is also used at the beginning of the study phase to take an overall image of the mosaic which will be attached to Data Form No 1 It is also often used to create a base image which will be used to make the maps At the end of an initial intervention of cleaning and stabilisation a new overall photograph of the mosaic should be taken to record its current condition The photograph should then be attached to Data Form No 1 Photographs are generally taken using a digital camera Traditional cameras with photographic films are still occasionally used but it is becoming more and more difficult to f
102. nservation Institute Institut National du Patrimoine Tunis 2013 25 Data Form No 5 Current Interventions This data form records the operations carried out on and around the mosaic The dates of the last intervention and last inspection if known as well as the date and duration of the current work and the date recommended for the next inspection are also recorded on this form Current Interventions Map The locations of the different types of executed interventions are marked on this map The composition of different mortars used for each intervention should be recorded on the legend of the Current Interventions Map If there is not enough room on the legend sheet page 28 to describe all the interventions an Additional Sheet should be used for the legend page 29 During each new intervention campaign a new Data Form No 5 Current Interventions should be filled out and a new Current Interventions Map drawn 26 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 DATA FORM NO 5 CURRENT INTERVENTIONS INTERVENTION PHASE MOSAIC ID INTERVENTION TYPE Initial intervention Maintenance cycle DATE OF PREVIOUS INTERVENTION DATE OF PREVIOUS INSPECTION DATE AND LENGTH OF CURRENT WORK DATE RECOMMENDED FOR THE NEXT INSPECTION TREATMENTS CARRIED OUT ON THE MOSAIC Vegetation removal Cleaning of the entir
103. ntegration of lacunae with tesserae with pieces of stone brick or other material inserted into the mortar Lifting and relaying on a Reinforced concrete cement support new support Other type of support Surface treatment Chemical cleaning Mechanical abrasion Application of a surface product resin wax etc Other L Parts detached and stored elsewhere L Reburial Draw a vertical section of the reburial describe the fill materials and separation membranes used provide the total thickness and the thickness of each layer PREVIOUS INTERVENTIONS AROUND THE MOSAIC Drainage Open shelter Wall stabilization Removable cover Closed shelter Other Access barrier DATES OF PREVIOUS INTERVENTIONS CARRIED OUT AND INFORMATION SOURCES PREPARED BY DATE Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 15 LEGEND PREVIOUS INTERVENTIONS MAP MOSAIC ID Mortar repairs ___ Infilling of lacunae Edging repair Outline of each infilling or edging mortar gt Overlapping between mortar layers new J old Filling of interstices between tesserae Reintegration of lacunae Reintegration with tesserae Reintegration with Detached mosaics Outline of the support panels of a detached mosaic re laid in situ
104. o the documentation of the last inspection to study the evolution of the deterioration processes and the performance of the previous interventions The entire maintenance process but in particular collecting data about the mosaic planning work and archiving the created documentation requires a close collaboration between the specialized maintenance staff and the site manager who plays a central role in the management of the archeological heritage 4 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 PART Documentation Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 1 DOCUMENTATION METHODOLOGY FOR MOSAIC MAINTENANCE Documentation is the collection of all information concerning the mosaic It is an essential component of any maintenance work It provides a better understanding of a mosaic and its condition before work is begun and makes it possible to record all the work carried out on the mosaic Documentation carried out during the regular inspection of a mosaic is a means to follow the evolution of its condition through time and to evaluate the efficiency of maintenance work Documentation can be generated in different formats written by filling out data forms graphic by drawing maps accompanied by their legends
105. om the rear 64 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Settings of a digital camera Whether the digital camera is automatic or manual a number of general settings should be adjusted before its use These settings are modified by pressing the Menu button of the camera and by following the instructions of the manual see Figure 10 FIGURE 10 Digital camera screen showing main menu The advice given below covers only the most basic and simple settings but they are sufficient for documentation required during the mosaic maintenance process Initial settings to be chosen before using the camera Display language You can chose the language used to display menus on the screen of the camera from a list of the most common languages Date and time The camera s date and time should be checked before starting to take photographs to verify that they are set correctly Indeed the date and the time when the photograph is taken are recorded together with each digital image Therefore it is important that they are correct for the archiving of the photographs The most important image related function settings Image format Some cameras offer a choice of image formats which have different width to height ratio The 4 3 format is the most common and it is suited to the needs of documentation for mosaic maintenance It corresponds to
106. on Institute Institut National du Patrimoine Tunis 2013 DATA FORMS AND MAPS Data Form No 1 Identification Information on the mosaic is gathered in Data Form No 1 such as its location within the archaeological site building and room its dimensions and its original construction technique Data Form No 1 also helps to collect and provides references to pre existing documentation on the mosaic i e past articles excavation reports old photographs plans drawings references to the country s national mosaic corpus if it exists for the site other publications etc A unique name or identifier can be assigned to each mosaic using the information collected in Data Form No 1 From then on this identification name of the mosaic or Mosaic ID should be used in all written graphic and photographic documentation pertaining to the mosaic The Mosaic ID comprises letters and numbers corresponding to the abbreviations of the site building and room where the mosaic is located If there already are letters and numbers assigned to the building and room for example from the national mosaic corpus or from an excavation report these should be used If none exist new ones should be created under the guidance of the site manager 10 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 DATA FORM NO 1 IDENTIFICATION STUDY PHASE MOSAIC ID
107. on Institute Institut National du Patrimoine Tunis 2013 73 In many softwares some of the basic menus that contain the most common commands located in the control bar to make them easily accessible The control bar is located at the top of the software window and contains the names of the basic menus such as File Page Layout View Help etc If you click on one of these names the corresponding menu opens and the most frequently used commands can be accessed A computer can be used at different moments during the documentation process of mosaic maintenance Data forms written documentation can be created and filled out using a word processing software Such software also allows one to write reports If a digital camera is available digital photographs can be uploaded to a computer If a scanner is available a drawing done by hand can be made into a digital image A digital photograph or drawing can then be used to create a base photograph or drawing by simply inserting the image onto a page using word processing software The page can then be printed on paper Using a specialized image processing software digital photographs or drawings can be edited Maps made by hand on paper can be scanned to obtain the same maps in digital form Maps of the graphic documentation can also be created directly on a computer if the appropriate equipment is available A computer then allows one to easily archive all digital documents and
108. one The difference is that only the minimum quantity of water is added to the quicklime to thoroughly transform it without leaving any excess water This produces slaked lime in the form of a white powder rather than as putty Like lime putty hydrated lime sets in contact with air it is therefore also non hydraulic lime Figure 19 As a powder hydrated lime must be stored in a dry place It can be turned into lime putty by adding water It can then be kept under water for a very long time 92 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 BURNING QUICKLIME Little water SLAKING Putty eo owder SLAKED LIME FIGURE 19 Lime cycle Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 93 Hydraulic binders Natural hydraulic lime powder Natural hydraulic lime often abbreviated as NHL comes from impure limestone containing other minerals silica alumina etc and has the capacity to partially set in the presence of water and partially in contact with air The manufacturing process of hydraulic lime is similar to that of non hydraulic lime except that the limestone is burned at a higher temperature Lime gets its hydraulic properties of setting in contact with water from the presence of these impurities that are
109. or the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 CLEANING A periodic maintenance program for in situ mosaics includes cleaning operations Within the framework of maintenance activities the purpose of cleaning operations is to remove substances and materials from the surface of the mosaic that could be responsible for its deterioration e to enable a better assessment of the mosaic s condition by making its surface more visible e to prepare the mosaic for mortar based stabilization treatments Before beginning to clean it should be ensured that cleaning is compatible with the mosaic s condition an overly forceful action on a fragile mosaic can lead to the detachment of tesserae If the mosaic is very damaged stabilization may be necessary to reinforce the mosaic before cleaning it In the course of the cleaning during mosaic maintenance anything that could potentially undermine the conservation of the mosaic should be removed For an in situ mosaic vegetation growing on or around the mosaic soil and other debris deposited on its surface and particularly in between the tesserae as well as micro organisms adhering to it should be removed Finally modern repair mortars if they are damaged or are damaging the mosaic should be removed The removal of soil especially when it is found under the tesserae is a particularly important operation to ensure that li
110. ortant to note the provenance and date of the photograph The choice between the two types of bases drawing or photograph will depend on the work environment and the characteristics of the mosaic A base drawing does not require specialized equipment only a pencil millimeter graph paper and measuring tapes are necessary For a very large mosaic it may be easier to draw it rather than create a photomontage Moreover a drawing remains better conserved over time than a photograph A base photograph is easier and faster to obtain for a smaller mosaic or for a mosaic with an intricate design that is difficult to draw A photograph provides a more detailed view of the entire surface A base photograph is therefore more appropriate for a mosaic that does not have a design where the tesserae themselves must be used as reference points Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 45 MAPS Once a base drawing or photograph has been created for the mosaic it is used to make maps Each map records with colors and symbols the position of various types of information related to the mosaic such as previous interventions conditions and current interventions page 60 Whatever type of base is used the maps can be drawn in two different ways Drawing directly on a copy of the base The information about the mosaic is directly recorded on a copy o
111. osaic surface which is much more damaging for the mosaic Figure 14 EVAPORATION MN zi TE Kae EAS VOULU J E ck e aes ood X FIGURE 14 Capillary rise of water Environmental conditions can affect the materials of the mosaic by triggering various deterioration mechanisms Table 2 Most of the time damage happens gradually through recurring aggressive action of the environment Below are a few simple explanations of how certain deterioration mechanisms related to the presence of water can occur Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 79 Salt crystallization due to wet dry cycles Ambient humidity diminishes when the temperature rises causing water contained in the mosaic to evaporate If the water contains dissolved salts these will be transformed into crystals during evaporation If the salts crystallize within the mosaic they fracture the materials containing them If they crystallize on the surface of the mosaic they form efflorescences generally white powder like or whisker like crystals loosely adhering to the mosaic surface After a long period of time salts can also form incrustations or mineral crusts that are often hard and compact which can strongly adhere to the mosaic surface Figure 15 WATER EVAPORATION N
112. osaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 THE DETERIORATION OF MOSAICS RE LAID ON REINFORCED CONCRETE PANELS AND REPLACED IN SITU When carrying out maintenance and conservation work on mosaics in archaeological sites one frequently encounters detached mosaics re laid on reinforced concrete panels and replaced in situ which are severely damaged in nearly all cases due to the deterioration of the support panel materials By far the most common deterioration mechanism of reinforced concrete panels is the oxidation of the grid of reinforcing steel bars which in particular causes an increase in the steel bars volume The presence of soluble salts in the cement but also the penetration of water through micro fractures promotes corrosion of the metal bars Steel corrosion products being more voluminous than the original metal will exert strong pressure on the concrete around them Over time this phenomenon causes cracking of the reinforced concrete panel which can lead to bulging of the tessellatum adjacent to the steel bar and its detachment from the panel This deterioration process which takes place with any reinforced concrete is accelerated and exacerbated by the use of poor quality materials and poor panel construction For example the damage will be aggravated if the panel is too thin whether it was done to reduce its weight or its cost or if the grid of bars was incorrectly positioned
113. otograph Map Revised base drawing or photograph 34 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 SITE NAME ARCHIVING DATA FORM MOSAIC ID aseq sdeyw sudej601oud paund SUONUdAJ9 U JUaLIND pue dew suonuaAJa1u qu24n ON W104 p ON W104 e1eq ON dew uonipuo pue dew ON dew uonipuo pue dew Z ON dew uonipuo pue dew L ON dew 1uauussessy uonipuo pue dew juauussassy uonipuo ON W104 e1eq pue dew ShOl 2Jd Z ON W104 e3eq pue uejd SATDAD 32NVN3INIV A pak PUD NOIL3TdWOO 3O SALva uone ynuep W104 e1eq aseg NOIVdWV J TWILIN 35 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 All the documentation for a site should be arranged by building Folders for mosaics
114. pplemental Manuals pages 3 6 Rectify each photograph then create a photomontage of the entire mosaic surface using an image processing software such as Adobe Photoshop see Supplemental Manuals pages 11 22 A photomontage is a single photograph created by putting together at least two photographs Insert the photomontage into a word processing document using a software such as Microsoft Word see Supplemental Manuals pages 7 10 and label the base photograph with the following information ID Mosaic ID Always write the Mosaic ID on the base Base made on Date Always write on the base the date it was made Title Leave empty on the base Date Leave empty on the base Prepared by Leave empty on the base The base photograph should be printed in color in A4 format or if it is possible and needed in A3 format Add by hand the graphic scale page 58 and an arrow indicating North Figure 5 Base Photograph The color print should be kept as the original of the base for eventual photocopying in black and white to make the maps It is also possible to directly print bases from the computer in black and white to make maps If a printer is not available it is possible to copy the photomontage onto a USB memory key or on a CD DVD and to print it in a specialized shop In this case all the information detailed above should be written with a pen to complete the base photograph Technician Training for the Maintenance of In Situ Mosaics
115. rable legislative regulatory and economic environment for the conservation of mosaics in the Mediterranean and promote the dissemination and exchange of information ISBN 978 0 9834922 5 2 online resource Front cover photographs by Elsa Bourguignon 2003 and 2004 and Richard Ross 2002 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 TABLE OF CONTENTS LINN RR adeptes FOO WOM eite Me DE D CCEA EEA ELEA T Introduction to the maintenance of in situ PART 1 DOCUMENTATION CHAPTER1 DOCUMENTATION METHODOLOGY FOR MOSAIC MAINTENANCE tT Documentation phases eese eet tenni ttnn tnn Written and graphic documentation onto Fonte tiii Data forms and maps tetendit feed ii dossier Data Form 1 Identification eret tentes Data Form 2 Previous Interventions essere Previous Interventions Map thiet Data Form 3 Condition Assessment sese Condition Assessment Maps No 1 2 3 and 4 sse Data Form No 4 Intervention Planning e Data Form No 5 Current Interventions eese Current Interventions Map eee
116. rating a central processing unit a screen a keyboard and a mouse which takes the form of a touch pad Figure 12 At equal performance a laptop often costs twice as much as a desktop computer It is also often more fragile The central processing unit CPU housed in the main computer case is the heart of the computer It is where calculations are performed and data are stored It contains the microprocessor which is the brain of the computer It processes and circulates information The CENTRAL PROCESSING UNIT CPU SCREEN ON BUTTON N X KEYBOARD US CABLE TO PRINTER DIGITAL CAMERA SCANNER ETC MOUSE j FIGURE 11 Desktop computer 70 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 ON BUTTON TOUCH PAD KEYBOARD CD ROM FIGURE 12 Laptop computer faster the microprocessor performs these tasks the more powerful the computer is The CPU also contains the hard drive It is the memory of the computer where all data are stored Even when the computer is turned off information remains stored in the hard drive To use a computer one must plug additional elements into the CPU called peripheral devices which make it possible for a person to communicate with the computer using a monitor a keyboard a mouse etc and to perform specialized tasks by using a printer a scanner
117. rea of the mosaic to be photographed and should be tightly framed to avoid the inclusion of other objects in the photograph 68 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 To care for the camera Avoid touching the lens and the screen on the camera body Keep the camera in a closed bag when not taking pictures It is a fragile object which is sensitive to dust Frequently upload all digital photographs to a computer The memory card will also be regularly reformatted by following the instructions in the camera s user manual Do not remove the memory card from the digital camera while the images are being uploaded to the computer Remove the batteries and the memory card when the camera is left unused for a long period of time Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 69 COMPUTER A computer is made of several components interconnected by cables A desktop computer is generally made of at least a central processing unit a monitor a keyboard and a mouse Figure 11 There are also laptop computers that are much smaller and lighter than desktop computers and can thus be easily transported anywhere A laptop has the same elements as a desktop computer but they are all integrated into a single object a flat box that opens incorpo
118. related to human activities These deterioration factors will act on the mosaic but the inherent properties of the materials of the mosaic will also influence the rate and extent of its deterioration Before intervening on a mosaic it is therefore also important to understand the causes of deterioration as well as to know the materials which make up a mosaic ENVIRONMENT Climate The climate of a site i e the weather conditions rain sun snow temperature etc prevailing in that area is one of the principle environmental factors In some climates changing weather conditions lead to large variations in temperature and humidity each day but also throughout the Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 77 year The more significant sudden and frequent these changes are the more they will lead to the deterioration of the constituent materials of a mosaic lime mortar stone etc through different mechanisms In a more stable climate these variations will be less significant slower and not as frequent consequently mosaics will suffer less deterioration All archaeological sites do not have the same climate and therefore do not suffer the same type of deterioration The climate of coastal sites located near the sea is generally more humid and more stable but they suffer the adverse effects of salty sea winds and salty sea wat
119. rotection required Reburial can be temporary between two excavation seasons or during the winter for example In these cases easily removable fill materials should be used i e by placing fill materials in bags and not in too great a thickness example D Figure 26 Reburial can be conceived as a long term protection within the framework of the conservation plan of an entire site if for example the choice is made to show only some of the mosaics to the public In this case the reburial design should provide for greater thickness examples B and C Figure 26 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 117 It may also be necessary to conceive reburial as a medium term protection or to design a reburial as a rescue measure to provide urgent protection for a mosaic in cases when a full intervention is not immediately feasible example A Figure 26 Reburial planning must be part of the general management and maintenance plan for a site Like any intervention it requires regular maintenance in particular any vegetation growing on or in it should be regularly removed to avoid further deterioration of the reburied mosaic Condition inspections of a reburied mosaic can be carried out regularly every few years especially if the reburial burden is fairly thin or if certain areas of the mosaic are fragile and it is therefore important tha
120. rried out around the mosaic Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 87 These three categories first aid maintenance and conservation represent the different possible levels of mosaic treatment from the minimum to the most complete Every mosaic can be the subject of each of these different treatment levels at different moments depending on its condition its exposure and the resources available for its conservation However regular maintenance should normally offset the need for first aid treatments The main work of a technician is to carry out mosaic maintenance but s he can also carry out some simple first aid operations and contribute to the conservation of mosaics under the supervision of a conservator In some cases when an excavated mosaic has been abandoned for years and therefore its condition is generally poor a technician must first plan and carry out stabilization work that can take a long period of time before s he can begin to carry our regular maintenance on the mosaic The operation of general stabilization of a mosaic in poor condition is called initial intervention It must be followed by maintenance cycles which consist of regular inspections of a mosaic already stable and in good condition accompanied if necessary by localized and relatively minor stabilization interventions 88 Technician Training f
121. s are effective separators of fill materials and prevent erosion of materials under them They generally avert root penetration and animal activity Performance related to liquid water water vapor transport depends on each type of geotextile which is why it is important to choose a geotextile carefully and ensure it is suited to the purpose it will serve in a reburial design Other synthetic fabrics may be used for mosaic reburial These are often non woven polyester fabrics used in agriculture or construction They are very similar to some geotextiles but they are of inferior quality and therefore generally have a shorter lifespans These materials are easier to find and less expensive than geotextiles It is generally not recommended to lay a geotextile directly over a mosaic because it is often difficult to ensure the intimate contact between the geotextile and the entire mosaic surface In places where this contact does not occur liquid water transport between the mosaic and the burial materials will not occur 116 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Reburying a mosaic As for any intervention reburial should be preceded by a thorough study of the mosaic including a condition assessment Some stabilization work should also be carried out before reburial It is especially important to remove any soil and all the plants and their asso
122. s follows 10 for documents relating to Data Form No 1 IDentification This category should be used for general photographs of the mosaic context for photographs used to create a base photograph as well as any detail photographs illustrating the execution technique of the mosaic More generally it should be used for any documents concerning the mosaic construction technique its history and its identification 2 for photographs and documents relating to Previous Interventions for photographs and documents relating to the Condition Assessment Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 37 APL for documents relating to the Intervention Planning 5Cl for photographs and documents taken after and or during Current Interventions 6WA for photographs and documents that are used as Working Aids that is as visual references to assist in carrying out a treatment Part 4 The file name should be completed by a short descriptive note that should describe its subject more precisely This note should be written with the help of the technical vocabulary found the map legends and the Illustrated Glossary If the description consists of several words the note should not contain any spaces but rather the first letter of each word will be capitalized for example if the description of a photograph is Detached tesser
123. s made with these materials are quite thick but not excessively heavy They can only be used if the re laid mosaic is kept in an environment protected from moisture like in a museum or in a storage facility Mosaics on plaster panels are usually installed vertically on a wall or more rarely on a floor Panels of cement mortar reinforced by a grid of steel bars reinforced concrete This type of support has been used since the early 20th century but it is particularly common for mosaics re laid between the 1950s and the 1980s These panels are usually quite thin but they are heavier and stiffer than panels made of wood plaster and hemp The mosaics re laid on reinforced concrete can be installed on walls or on floors in a museum or in a storage facility but they can also be replaced outdoors in an archaeological site Composite panels often laminated made of modern synthetic materials A common type of composite panel is composed of aluminum honeycomb sandwiched between two layers of fiberglass reinforced resin This type of support is more recent and has been used since the 1980s These panels are thin and very light They are mainly used for mosaics kept indoors in museums and in storage usually installed on walls They can also be used for displaying mosaics on floors in museums or more rarely in archaeological sites under a shelter if they are not subject to being walked on Technician Training for the Maintenance of In Situ M
124. s preferable to work with materials that are easy to disassemble and remove from the mosaic surface without causing damage Separation of reburial layers For a separation membrane to be an efficient divider its mesh size should be smaller than the particle size of the fill material above it Availability and cost The choice of materials is often limited by their cost and their local availability For example soil removed during excavation is sometimes used for mosaic reburial because it is readily available and at no cost Its use is particularly easy if it is reused shortly after excavation when the soil is still loose and devoid of vegetation Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 111 Fill materials Fill materials generally used for reburial are soil sand gravel or specialized materials expanded clay pellets Leca volcanic tuff pellets beads or plates of expanded polystyrene etc Each has its own advantages and disadvantages and their use have positive and negative impacts on the mosaic Table 3 Soil Soil is the material that is most similar to the one that preserved the mosaic for centuries until its excavation There is a great variety of soils each with their own properties In general soil provides good liquid water water vapor transport It also provides a good stability in temperature and humidity if s
125. s should be chosen according to the camera lens used and the work environment Set the zoom lens to wide angle to have the widest possible framing If it is possible to photograph each sector from a 2 meter height while being located 2 meters away from the center of the sector Figure 5 Taking the photograph square sectors measuring 120 cm x 120 cm are appropriate If it is possible to take the photographs from a height of more than 2 meters or if the camera can offer a wider framing the size of the squares can be increased and therefore their number can decrease 54 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 W W Ru s amp 2 amp 2 f m if X x 2 i i lt amp 22 pu amp 2 8 OG S amp 2 md Nd HE 5 2 S 5 22 RN 3 1 E 2 5 uv to Zi f 48 j ER Zu M v 2 g 2 2 d E 5 A TRA 15 5 3 Z 5 18 A gt For Z 5 e Z mn cmd HH x M 2 v Sa nou z 2 SN SRM 55 FIGURE5 Base photograph by photo montage Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Make a schematic drawing of the room and mosaic Indicate on the drawing the sec
126. saic On a base drawing or photograph the frame of each photo should be represented by a rectangle with the corresponding digital photo file number written in its upper interior corner This same number will be kept in the photo name in the 4th part Note on the subject when the photo is given its final name for archiving purposes page 38 32 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 PHOTOGRAPH LOG SITE NAME LOG SHEET NUMBER Digital fila No Mosaic ID Date Category Note on the subject CATEGORIES Identification 4PL Planning 2 Previous Interventions 3CA Condition Assessment 5CI Current Interventions 6WA Working Aid Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 33 ARCHIVING All the documentation components created during the mosaic maintenance process whether in paper form or in digital form should be properly organized and conserved so that they can be readily accessed and used in the future These documents together form the mosaic conservation archive of a site The archiving of the documentation is therefore a very important step in the mosaic maintenance process
127. sideration to ensure that the effects of reburial on the conservation of a mosaic are positive and to minimize the potential negative effects First of all a condition assessment of the mosaic should be made trying also to understand the causes of its deterioration It is necessary to understand the properties of each material intended to be used so that the reburial protects the mosaic from environmental conditions Fill materials such as soil or sand are used in more or less thin or thick layers to create a more stable environment and to better protect the remains on the site Separation layers such as plastic netting are thin layers used in sheets to avoid mixing the different fill materials or to mark the boundary between these materials and the surfaces to be protected and to thus avoid their contamination Separation layers can also be used in the form of bags containing fill materials 108 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 ity o rj 2 we 74 SI d 109 ial FIGURE 26 Examples of rebur BAGS OF SAND Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Important factors affecting the performance of a reburial Water transport through the materials It is impor
128. t they are regularly monitored However the maintenance of a reburied mosaic is generally less time consuming than that of a mosaic left exposed in the open air Reburial is therefore an intervention that should be carried out when human or financial resources are not sufficient to properly maintain a mosaic left in the open air or under a shelter 118 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 CHAPTER 6 MAINTENANCE OF MOSAICS RE LAID ON REINFORCED CONCRETE PANELS AND REPLACED IN SITU THE DIFFERENT METHODS AND MATERIALS WHICH HAVE BEEN USED TO DETACH AND RELAY MOSAICS In the past the most common way to conserve mosaics was to remove them from their original location and to re lay them on a new support a practice that continues today Mosaics were then displayed in a museum placed in storage or replaced on site in their original location This practice of detaching mosaics from their original foundation mortars is now regarded as inappropriate not only because the detachment process damages a mosaic but also because of the consequent loss of most of the original material of a mosaic as well as its architectural context thereby severely compromising the authenticity of a mosaic The detachment and lifting of a mosaic is currently considered an option only in very exceptional cases A detached mosaic suffers its initial damage during the l
129. tant for water to circulate freely between the reburial and the mosaic If liquid water contained in the soil cannot pass easily from the mosaic to the fill materials above it causing discontinuity in the capillary moisture rise then water will evaporate at the mosaic surface This will cause the crystallization of salts if any are present in this area and eventually the deterioration of the mosaic Fill materials that do not allow liquid water to pass through impermeable materials will trap moisture inside the mosaic leading to the growth of micro organisms and the development of roots It is also important that fill materials allow the mosaic to dry slowly when it is damp and to absorb water slowly when it is dry that is that they insure that the humidity within the mosaic changes slowly Temperature stability thermal insulation Fill materials should insulate the mosaic as much as possible from temperature variations especially they should prevent it from freezing in the winter or becoming too hot in summer Extremely low or high temperatures or very frequent changes in temperature cause deterioration of stone and mortar The thicker a reburial fill layer is the better insulation this layer will provide Vegetation growth and burrowing animals Preferably fill materials should impede vegetation growth Therefore materials should not retain moisture for long periods of time They should not contain nutrients for plants or
130. ter measured on the actual mosaic Finally draw a line of 9 5 cm on the base drawing and write at its ends 0 and 1 meter Figure 7 0 0 10 0 50 1 meter Scale 1 9 5 cm 1 2 10 11 12 13 14 4 5 6 7 8 9 15 FIGURE 7 Graphic scale Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 59 MAKING Steps Copies of the base drawing or photograph or Base and sheets of tracing paper or transparency film if it is not possible to make copies of the base Drawing board Pencil and eraser Colored pencils or felt pens for the copies of the base and the sheets of tracing paper or Permanent markers for transparencies White corrector fluid If the maps are to be drawn directly on copies of the base drawing or photograph Photocopy the base previously printed in color on A4 or A3 paper reducing it or enlarging it as needed For a base photograph the copies should be as light as possible while keeping the mosaic visible so that the colored mapping is legible It is also possible to directly print bases from the computer in black and white to make plans If the maps are to be drawn on separate transparent sheets independent from the base Overlay the sheets of tracing paper or transparency film onto a black and wh
131. the edges of the mosaic as well as localized stabilization work They are generally carried out over a short period of time when the mosaic is exposed for the first time during excavation or during construction work or when an excavated mosaic has suffered sudden damage or prolonged neglect Emergency treatments should be documented but the documentation can be carried out quickly Conservation The purpose of conservation treatments is to restore both the structural and the aesthetic integrity of the whole mosaic They generally include the following operations cleaning of the surface e stabilization of the tesserae and mortar layers consolidation of the materials of the mosaic stone brick mortar etc e operations of aesthetic presentation 86 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Conservation treatments should be based on preliminary investigations conducted to obtain a comprehensive condition assessment of the mosaic and on analyses to try to identify the causes of the deterioration of the mosaic Investigations and analyses enable a conservator to establish a methodology the types and sequence of operations to be carried out and the materials to be used as well as a conservation program duration and cost of labor Conservation programs must include a maintenance program for the mosaic over the long term aft
132. the future their work on mosaics will need to be supervised directly by professionally trained conservators when they become available The technicians will be part of a larger team that includes workers carrying out less specialized maintenance activities on a site as a whole such as controlling vegetation and visitors The work of the mosaic maintenance technicians will form an integral part of the prescribed activities of a site management and conservation plan to be developed and executed by the trained manager of the site Such a plan would identify among other things which mosaics should be protected by reburial and then maintained which should be protected by permanent shelters presented to the public and maintained which should be covered seasonally and maintained and which should be left unprotected and maintained most frequently Despite the urgent need to address the deterioration and loss of in situ mosaics many detached mosaics that were re laid at archaeological sites over the past decades are in need of maintenance or a new support panel Training in the conservation of in situ mosaics on their original bedding was considered a priority by the organizers because before treating mosaics re laid on reinforced concrete panels it is important to be familiar with authentic ancient mosaics and know how to maintain them The treatment of detached mosaics involves the use of different materials tools and techniques because their modern s
133. the last inspection or intervention should be recorded If some of these phenomena seem to reoccur from one intervention campaign to the next these observations should be noted in the space reserved for comments on the data form Inspecting the condition of the mosaic provides the opportunity for assessing the need and the urgency of a new intervention campaign If the general condition is good another inspection will be scheduled at a later date If new deterioration phenomena have appeared it will be necessary to schedule a new intervention At this time a new Current Interventions Map will be drawn using the base drawing or photograph that was revised after the initial intervention corrected drawing or new overall photo A new Data Form No 5 Current Interventions will also be completed All new maps should use the same legends as those used for earlier maps All newly created documentation material data forms maps and photos must be placed in the same mosaic archive folder as the previous documentation New data forms new maps and new photos should be grouped together by maintenance campaign 40 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 e ueue1urelw dow pub oN DJD Mau K1Dssa au SI 1 JI ON DIDG A 3unini aseyd
134. tograph is taken lens aperture to change the amount of light entering the camera when a photograph is taken this changes the depth of field the distance between the nearest point and the furthest point in reality which are both in focus in the image Framing can be modified without the photographer needing to move if the camera has a zoom or by changing lens In the first case by adjusting the zoom lever for compact cameras or by turning the zoom ring for reflex cameras it is possible to obtain a wider framing for more general views or a closer framing to take pictures of details If several lenses are available a wide angle lens 28 35 mm should be used to take general photographs and a normal lens or a telephoto lens 40 80 mm should be used for the close up photographs Fully automatic cameras or cameras set in automatic mode The focus of the subject the shutter speed and the lens aperture are set automatically when the shutter button is pressed halfway All settings are then correct and the shutter button can be pressed completely to take the photograph Semi automatic or manual cameras The focus of the subject can be adjusted automatically by almost all cameras If this function called autofocus exists it is advisable to use it by setting the focus mode switch located on the lens to AF The camera then automatically focuses when the shutter button is pressed halfway The focus can be adjusted manually by turni
135. tors created with sticker dots and write down their dimensions In this sector grid assign a number in order to each vertical column starting with 1 and a letter from A to Z to each horizontal row Each picture will be identified by the letter number code corresponding to the photographed sector For example The photograph of the sector located at the top of the first column and in the first row to the left will be referred to as A1 Photo B1 will be located directly underneath photo A1 photo A2 will be the photograph to the right of A1 etc Figure 5 Schematic drawing Before taking each photograph place within the photo frame but outside the sector being photographed the metric photo scale and the chalkboard on which the mosaic ID and the sector letter number code are written Indicate North on the chalkboard or with an arrow next to it Adjust the camera zoom page 62 so that the entire sector to be photographed marked by the sticker dots is visible in the photo frame Also include in the frame a part of each adjacent sector where the chalkboard and the metric photo scale are placed If all the photographs are taken from the same distance the zoom must be adjusted for the first photograph and must be kept the same throughout the entire photographic survey of a mosaic If the camera is used in manual mode adjust also the shutter speed and the lens aperture so that the every area of the image is in focus page 67 Photograph th
136. two mosaics from the same site or from two different sites or between the maps of different maintenance cycles of the same mosaic A list of materials needed for the documentation of mosaics is provided in Appendix A page 124 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 47 MAKING A BASE DRAWING DIRECTLY USING A GRID Equipment Soft brush String Equipment to keep the strings taut nails wooden planks stones etc Folding ruler retractable measuring tape reel measuring tape Large wooden framing squares to check right angles when setting up the grid Drafting triangle Drawing board Graph paper Tracing paper Masking tape Pencil and eraser 0 1 or 0 2 ultra fine point pen and razor blade Compass Colored sticker dots Steps Figure 4 Remove dirt and sand from the mosaic surface with a soft brush if it is possible to do so without damaging it Set up a grid over the mosaic by stretching strings across it at regular intervals for example 50 cm to create squares The grid squares must always have 90 angles right angles and therefore the strings must be placed using a large wooden framing square The strings can be fixed to the ground with nails in areas devoid of tesserae or original mortar otherwise they must be attached to stones wooden planks or by other means that do not damage the mosaic 48
137. ufficiently thick It is often readily available during or after excavation and in this case it does not cost anything However it generally contains seeds and little plants and facilitates vegetation growth and animal activity Consequently it sometimes needs preliminary sieving and requires more frequent maintenance It can also be eroded by rain and wind Finally soil will dirty the mosaic when in direct contact which will require extensive cleaning if the mosaic is later presented especially if the mosaic is in poor condition Sand Sand is generally less prone to vegetation growth and animal activity than soil It therefore requires less maintenance Sand is also cleaner but may sometimes contain salts It will require less cleaning after its removal but its small grains can still be difficult to remove from the most damaged parts of a mosaic Moreover liquid water water vapor transport and temperature stability are not ensured as effectively by sand as by soil for the same thickness It can be eroded by rain Gravel Gravel is the material that best prevents vegetation growth and animal activity due to the size of its particles It is also easy to remove from the mosaic surface and is less eroded by rain than soil or sand However it is hard and has sharp edges and can be heavy It does not provide good liquid water transport and good temperature and moisture stability because of the spaces between particles 112 Technicia
138. upports usually made of reinforced concrete perform and deteriorate differently from ancient lime mortars Therefore it was considered more appropriate to envisage the treatment of detached and re laid mosaics as a topic to be addressed at the end of the basic technician training on the maintenance of in situ mosaics The didactic materials presented hereafter were first developed for the training course on the maintenance of in situ mosaics organized in 2001 for workers employed by the Institut National du Patrimoine of Tunisia They were designed to help them both during training campaigns on site and afterwards during their future work as maintenance technicians These didactic materials include summaries of the main topics taught during the course with references to supporting documents which are provided during the course as well These materials also provide the trainees with a methodology for creating the documentation and carrying out the technical tasks involved in mosaic maintenance This collection of documents however was not designed as a self contained manual It does not describe in detail as a manual would the different operations that are part of mosaic maintenance work although these were of course part of the curriculum taught on site over several months combining classroom lessons and practical exercises all essential to X Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institut
139. user can organize his or her computer desktop as s he wants For example the trash or recycle bin is located on the desktop which is where files that have just been deleted are temporarily stored In the bottom left corner of the desktop a button sometimes called Start enables one to open all the softwares installed on the computer but also to access various files and folders It is possible to open several programs and files at the same time Each will open in a different window Using the Start button one can also look for a specific file make many adjustments to the computer etc It is also by using this button that the computer is turned off after use One must never shut down a computer by pressing the power button on the machine one must always click on the Start button and find the Shut Down command A menu is a list of commands that generally appears in a rectangle and which enables to do different actions A menu appears when one clicks with the mouse in a particular area of the screen One can then select one of the menu commands by clicking on it with the left mouse button Usually the list of commands in a menu does not change but there is a particular type of menu called the contextual menu the contents of which change depending on where the mouse cursor is located One typically opens a contextual menu by a right click of the mouse Technician Training for the Maintenance of In Situ Mosaics Getty Conservati
140. vement It is characterized by the use of small sized elements usually 5 to 20 mm wide called tesserae They have a more or less regular shape usually quadrangular and are cut by hand The outermost layer of a mosaic containing the tesserae is called tessellatum A mosaic is made by placing tesserae side by side in more or less regular rows following an outline or filling a given space The tesserae of a mosaic can all be made of the same material and be of only one color or be made of different materials and several colors A mosaic made of tesserae of only one color is called monochrome one made of two colors of tesserae generally black and white is called bi chrome a mosaic made of tesserae of several colors is called polychrome A tessellatum containing two or more colors that create a geometric design is called a geometric mosaic If the tessellatum forms a figurative image it is called a figurative mosaic Finally some mosaics have both geometric and figurative designs If the tesserae are extremely small less than 4mm wide the mosaic can be called opus vermiculatum The layer into which the tesserae are inserted is called the bedding layer It is made of a mortar very rich in lime so that it stays soft and workable over a long period In addition the bedding layer mortar is laid out a section at a time so that it remains soft during the whole tesserae inserting process Technician Training for the Maintenance of In
141. with air Binder aggregate ratio The ratio of binder to aggregates strongly influences the properties and performance of a mortar Most of the time one part in volume of binder is mixed with two to three parts of aggregates that is a binder to aggregate ratio between 1 2 and 1 3 in volume A mortar containing more lime a lime rich mortar is easier to use more malleable and adheres more easily but it will tend to have larger shrinkage and will therefore crack more easily while setting This is especially true for lime putty mortars Once set a lime rich mortar is also softer than a mortar containing more aggregate A mortar containing less lime a lime poor mortar is less malleable and adheres less easily but it will tend to shrink less Once set a lime poor mortar is more friable than a mortar that contains less aggregate Mortar shrinkage is due to the mortar decreasing in volume when it loses water 96 Technician Training for the Maintenance of In Situ Mosaics Getty Conservation Institute Institut National du Patrimoine Tunis 2013 Particle size distribution of aggregates The particle size distribution of aggregates also influences the properties and performance of a mortar To make a good mortar aggregates should have a good particle size distribution between coarse and fine particles If all the particles in a mortar are the same size they will form unequal voids poor compaction and there will be a greater

Technician Training for the Maintenance of In Situ Mosaics

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