Web Offset Heatset Troubleshooting Guide
Contents
1. Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause Press 1 Web tension too high 2 Printing units or press elements out of line often indicated by diagonal wrinkles in web 3 Improper blanket pressures Ink 4 Ink too tacky 5 Ink body may be too long causing drips from fountain nip to web 6 Ink pigment too weak causing ink fountain key to be opened and allowing ink to drip 7 Ink misting slinging Solution Press 1 Reduce web tension 2 Check and adjust press alignment 3 Adjust blanket packing to manufacturer specifications Ink 4 Consult ink manufacturer to reformulate ink with less tack 5 Consult ink manufacturer to reformulate ink 6 Consult ink manufacturer 7 See MISTING SLINGING Flint Group2. and or scratch removers have dried on plate image 4 Fountain system contaminated by Ask about detergent gt Flexography 5 Excessive fountain solution in ink gt Pub Gravure gt Pkg Gravure 6 vd daisies gt Sheetfed Offset Improperly developed plates gum gt UV adheres to image area gt Web Offset gt News Ink HOME Solution 1 Adjust fountain solution to proper pH conductivity Re etch plates and rub up image areas with press ink drain fountain solution and fill with tap water if image returns replace tap water with fountain solution containing less gum Rinse plate thoroughly and immediately after using these materials Thoroughly rinse all parts in contact with detergent before re installing in press Reduce dampener setting to minimum level consult ink manufacturer Wash plate thoroughly remake if necessary FlintGroup Web Offset Heatset Troubleshooting Guide Plate Blinding Mechanical Symptom Part or all of image on plate does not take ink See Plate Blinding Chemical Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 2 3 Excessive linting Excessive plate to blanket pressure Improperly set ink and dampening form rollers Abrasive particles destroying images Solution See PICKING LINTING Use pressure gauge to check pressure adjust to proper level
3. is 72 75 F CAUTION If chill rolls are too cold condensation can occur Reduce oven temperature to minimum necessary to get web through chilling and press folding operation For impingement dryer adjust flame tips to impinge properly for velocity forced air dryer raise air temperature decrease press speed increase air circulation consult ink manufacturer for faster drying ink CAUTION Paper will burn at 451 F and can scorch at lower temperatures Consult dryer manufacturer Consult paper manufacturer change stock Reduce ink film raise air temperature in dryer reduce press speed to increase oven dwell time consult ink manufacturer for faster drying ink FlintGroup Web Offset Heatset Troubleshooting Guide Misting Slinging Symptom Excessive amount of ink being thrown from ink train rollers Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 Excessive ink on rollers 2 Improper ink water balance 3 Improperly set or worn rollers 4 Roller train too hot 5 Ink too long in body Solution 1 2 3 Adjust press to carry less ink consult ink manufacturer for stronger ink Adjust to proper ink water balance Adjust roller to appropriate settings replace if necessary Reduce temperature or increase flow of cooling water through rollers Consult ink manufacturer Flint Group Web Offset Heatse
4. reduce press speed Adjust press setting to carry less ink consult ink manufacturer Increase velocity of air in air knife scavenger at dryer exit Reduce chill roll temperature while avoiding condensation Change stock Adjust fountain solution to proper pH conductivity Adjust to proper ink water balance consult ink manufacturer Clean dampeners thoroughly check windows vents and forced air systems to prevent drafts Adjust oven temperature reduce press speed 10 Consult ink manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Gloss Symptom Ink has improper reflective properties Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 Stock too absorbent paper surface too rough grainy Press dampeners inking system contains excessive water Ink film too thin Dryer temperature too high Excessive ink vehicle penetration into stock Solution 1 Change to smoother nonabsorbent stock with more ink hold out consult paper manufacturer Reduce amount of fountain solution consult ink manufacturer for more water resistant ink Increase ink film thickness Reduce press speed to allow lower oven temperature consult ink manufacturer to reformulate ink Reduce dryer temperature and maintain sufficient chilling capacity increase press speed to reduce oven dwell time consult ink manufactur
5. Check setting and durometer adjust or 1 2 3 replace Check ink grind fountain solution solvents etc replace contaminated materials Flint Group Web Offset Heatset Troubleshooting Guide Poor Mileage Symptom Too few impressions per pound of ink Cause I 2 Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Lack of control of ink densities Ink penetrates stock too quickly Improper ink water balance Low pigmented inks Excessive waste on start up Improper estimates from job to job Solution 1 Adjust to lower print densities while maintaining acceptable quality Consult ink manufacturer for ink with more holdout use less porous stock Adjust to proper ink water balance Consult ink manufacturer to reformulate ink with more strength Improve start up procedures Establish ink history and consistent procedure to improve estimates FlintGroup Web Offset Heatset Troubleshooting Guide Register Running Direction Symptom After the press has been set for proper registration misregistration occurs in running direction Solution Cause 1 2 Ask about gt Flexography T gt Pub Gravure gt Pkg Gravure 8 gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME One or more plates are improperly set on cylinders One or more plates are printing l
6. Gain On Press Symptom Printed halftones appear muddy show higher values than proof Cause 1p 2 3 4 5 Ask about gt Flexography 6 gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Improper pressure settings between plates blankets and roller Doubled or slurred dots Ink viscosity too low Ink too water receptive Plate not sharp enough Ink color strength too low Solution 1 gt A Adjust to proper pressure settings Adjust plate to blanket pressure check for and correct blanket and roller slippage assure mechanical stability at high speeds Consult ink manufacturer Consult ink manufacturer Coordinate with prepress for sharper halftones negatives positives and plates Consult ink manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Dot Gain Prepress Symptom Dot gain occurs during prepress reproduction Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause Film 1 Dots on film too soft too much fringe 2 Dot percentages on the film inaccurate Plate 1 Negative plates over exposed 2 Poor contact between film and plate in vacuum frame 3 Improper lamp spectral intensity aged lamps 4 Plate is underdeveloped or has insufficient support next to brushes 5 Incorrect digital plate curve be
7. Web Offset Heatset Troubleshooting Guide Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME gt Blistering gt Blocking gt Color Variation gt Dot Gain On Press gt Dot Gain Prepress gt Drying gt Gloss gt Hickies gt Ink Water Balance gt Marking gt Misting Slinging gt Mottle gt Picking Linting gt Piling gt Plate Blinding Chemical gt Plate Blinding Mechanical gt Poor Mileage gt Register Running Direction gt Register Side to Side gt Roller Stripping gt Rub Off Scuffing gt Scumming gt Tinting Toning gt Trapping gt Web Breaks Paper gt Web Breaks Press Ink Flint Group Web Offset Heatset Troubleshooting Guide Blistering Symptom Moisture explosions in the paper cause bubbles to form Cause 1 Oven heat too high 2 Excess dwell time in oven 3 Paper has excessive moisture improper density or base 4 Ink pigmentation too low Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Solution 1 Reduce oven temperature consult ink manufacturer for inks compatible with lower temperatures Adjust press speed web dwell time in dryer and chill roll temperature to optimum levels Run roll from different paper machine posi
8. entration of fountain solution Pressure between plate and blanket too high Improper setting of dampener or ink rollers Ink insufficiently resistant to water Improperly exposed or developed plates Improper ink water balance Paper chemicals contaminate ink train Prolonged use of detergent or clean up solution Solution 1 Adjust concentration of alcohol or alcohol substitute in fountain solution consult ink manufacturer Adjust fountain solution to proper pH conductivity Adjust pressure to manufacturer specifications Adjust dampener ink rollers to manufacturer specifications Consult ink manufacturer to reformulate ink with greater water resistance Replace plates if necessary adjust plate making process Adjust to proper ink water balance Use low tack ink low water setting and low pressure setting change paper Remove detergent with water or petroleum solvent and change solution FlintGroup Web Offset Heatset Troubleshooting Guide Trapping Symptom Cannot achieve good color balance or overall appearance Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause di 2 D 7 Tack of inks out of sequence Improperly balanced ink strength Unequal press stability of inks succeeding inks tack up more quickly than preceding inks Additive in ink creates film preventing subsequent inks from adherin
9. er for ink with more hold out FlintGroup Web Offset Heatset Troubleshooting Guide Hickies Symptom Donut shaped or irregularly shaped white spots on printed surface Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause Solution 1 Dried ink particles 1 2 Roller particles 2 3 Glazed roller 3 4 Foreign particles 4 5 Loose paper coatings or dust 5 Clean press thoroughly and regularly remove dried ink from fountain and roller ends Replace rollers if necessary Use specially formulated glaze removing materials or scrub roller with pumice and solvent Improve housekeeping a check air systems for circulation of dust b vacuum surface of overhead fixtures such as lights c hang plastic sheeting over press Consult paper manufacturer to install vacuum sheet cleaner NOTE Properly maintained hickie picker rollers do work All require frequent scrubbing for optimum performance FlintGroup Web Offset Heatset Troubleshooting Guide Ink Water Balance Symptom Frequent adjustments required on press to maintain print quality Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 Excessive or insufficient fountain solution 2 Improper concentration of fountain solution 3 Improper dampening roller setti
10. essive emulsification of ink Improperly set rollers Ink too strong Ink too water resistant Solution 1 N Adjust fountain solution to proper pH conductivity Reduce dampener settings Clean copperized rollers ink rollers and wash again use less gum in fountain solution Remove rollers from press de glaze appropriately and rinse well Reduce dampener settings consult ink and dampening solution manufacturers Adjust rollers to proper setting Consult ink manufacturer Consult ink manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Rub Off Scuffing Symptom Printed ink appears dry but exhibits poor resistance when abraded Cause ie 2 3 Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset 8 gt UV gt Web Offset gt News Ink HOME Improper ink water balance Paper contains too much water Excessive ink Improper pH of fountain solution Improperly formulated ink Rough paper surface creates poor rub between unprinted and printed surfaces Ink dries too slowly Poor paper coating integrity Solution 1 2 3 Adjust to proper ink water balance Change paper Adjust press to carry less ink reduce print density Adjust fountain solution to proper pH conductivity Consult ink manufacturer to reformulate ink with more binding vehicle or rub resistance Consult paper manufacturer for more absorbent stock consult ink manufacture
11. g Improper ink water balance Poor ink release from blanket Improper register Solution 1 Adjust inks to have progressively lower tack Adjust inks to have progressively heavier film for optimum traps Consult ink manufacturer Consult ink manufacturer Adjust to proper ink water balance See MOTTLE Consult blanket manufacturer consult ink manufacturer See REGISTER FlintGroup Web Offset Heatset Troubleshooting Guide Web Breaks Paper Symptom Web routinely tears as it passes through press See Web Breaks Press Inks Cause 1 Excessive tension on edge s of 1 web due to loss of moisture and shrinkage 2 Roll has dent or cut at end 2 3 Fiber cuts hair cuts wire holes 3 wrinkles slime spots foam spots etc 4 Bad mill splices 4 Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Solution Keep rolls completely and carefully wrapped until mounted on press Sand or cut paper until edge is smooth if possible otherwise remove damaged portion of roll and replace consult paper manufacturer Consult paper manufacturer if defects are common Consult paper mill if defects are common Flint Group Web Offset Heatset Troubleshooting Guide Web Breaks Press Inks Symptom Web routinely tears as it passes through press See Web Breaks Paper Ask about gt Flexography gt
12. ing applied for paper ink combination Solution Film 1 Check films for halos or veiled dots increase the output resolution on image setters 2 Measure the films to determine accuracy if necessary recalibrate image setters Plate 1 Use a plate control target and plate reading instrument to evaluate the plates cut back on plate exposures 2 Check vacuum gauge 25 27psi look for clogged hoses worn areas and or leaks 3 Change the vacuum frame lamps track and record usage of time on lamps 4 Check developer chemistry and brush support contact 5 Apply correct curve to plate FlintGroup Web Offset Heatset Troubleshooting Guide Drying Symptom Ink film tacky during press delivery and binding resulting in selo a marang Ask about gt Flexography gt Pub Gravure gt Pkg Gravure 9 gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME 6 Dryer temperature too low for press speed insufficient solvent release from ink Ink film too thick Insufficient evacuation of solvent vapors from web as it leaves dryer Chill roll too warm ink resins failing to set adequately Paper contains excessive water non porous stock Improper fountain solution pH conductivity Ink taking up too much water Uneven plate dampening Ink film only dries on surface trapping solvents 10 Ink films do not dry at normal temperatures Solution 1 9 Increase dryer temperature or
13. lanket too tacky Ink too tacky for stock Solution 1 2 3 Adjust to proper ink water balance Adjust fountain solution to proper pH conductivity Make tape pulls from blanket consult paper manufacturer Reject stock if necessary change to more lint or pick resistant stock Adjust press repack to manufacturer specifications Consult blanket manufacturer change blanket wash treat blanket or change to less tacky blanket Consult ink manufacturer to reduce ink tack FlintGroup Web Offset Heatset Troubleshooting Guide Piling Symptom Build up of ink on printing plates Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause A 2 3 Paper problems Improperly packed cylinders Improperly set or worn rollers Ink is waterlogged Ink drying too fast Solution See PICKING LINTING Check specifications and adjust 1 2 3 cylinders Check specifications and adjust rollers replace if necessary Adjust dampener settings consult ink manufacturer Consult ink manufacturer to adjust tack and stability Flint Group Web Offset Heatset Troubleshooting Guide Plate Blinding Chemical Symptom Part or all of image on plate does not take ink See Plate Blinding Mechanical Cause 1 Fountain solution too acidic 2 Excessive gum in fountain solution 3 Plate cleaners
14. ng 4 Improper ink form roller settings 5 Improper ink fountain settings Ink too weak Ink taking up too much water Solution 1 Adjust dampener settings to proper levels Adjust fountain solution to proper pH conductivity Reset rollers insure that dampener rollers are driven by vibrator roller and not plate Conduct ink stripe test to check form roller pressure adjust if necessary Adjust ink at fountain to proper level allow adequate time for adjustment to take effect Consult ink manufacturer Adjust ink water balance consult ink manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Marking Symptom Streaks tracks or smudges on web due to mechanical contact Cause 1 Grater roller points too dull 2 Web bustle wheels touch image areas 3 Improper air flow Chill roll too warm 5 Web temperature too low to drive off solvents 6 Press speed or job type beyond dryer capabilities 7 Non absorbent stock 8 Ink film too thick Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Solution 1 2 3 g N Install grater roller with sharper points Move wheels so they touch only non image areas apply TEFLON tape to make wheels less abrasive Adjust airflow through oven adjust web tension Reduce temperature for post chill roll temperature of 90 F or less recommended temperature
15. o side misregister just after splicing Paper varies in caliper across the web 4 Web has slack edges due to moisture pick up while in the roll Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME 5 Ink tack too high at point of impression Solution 1 Increase distance between infeed and first printing unit use preheater on infeed and first printing unit to dry paper even moisture content and flatten web equip press with curved roller to spread and flatten web Remove outer 25 mils of paper do not unwrap rolls until just before going to press Consult paper manufacturer Keep rolls protected from atmospheric changes until they are mounted on the infeed stand increase distance between infeed and first printing unit increase web tension to tighten slack edges equip press with curved roller on infeed to spread and flatten web adjust the eccentric mounted infeed roller to balance edge tension Consult ink manufacturer Flint Group Web Offset Heatset Troubleshooting Guide Roller Stripping Symptom Rollers do not accept ink Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 N Fountain solution too acidic Excess water on press Desensitized metal vibrator rollers Glazed form roller Exc
16. onger or shorter than others Uneven blanket packing web tension 3 will build up until the web snaps back Web tension too low Web tension changes during run because infeed tension changes Ink tack at point of impression too high causing web to follow blanket can increase tension in localized areas Paper pile on blanket changes blanket diameter Paper roll out of round or has flat areas 1 2 4 5 7 8 Handle plates more carefully on bending jig Transfer packing from blanket to plate to shorten printing or from plate to blanket to lengthen printing maintain good web tension Adjust blanket packing until draws between units are equal Increase web tension in infeed section of press Equip press with constant tension infeed Increase web tension reduce press speed consult ink manufacturer for ink tack reduction Wash blanket more frequently change to more moisture resistant paper Use constant tension infeed increase distance between infeed and first printing unit change to roll without problem Flint Group Web Offset Heatset Troubleshooting Guide Register Side to Side Direction Symptom After the press has been set for proper registration misregistration occurs laterally Cause 1 Non uniform moisture content across web causes corrugation of roll 2 Welts caused by rolls unwrapped in high humidity and allowed to stand Welts occur not more than 25 mils into roll and can cause side t
17. r to reformulate ink with more rub resistance See DRYING Consult paper manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Scumming Symptom Non image area of lithographic plate accepts ink in random areas Cause a 2 Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Plate improperly processed or exposed to light Low alcohol or alcohol substitute content in dampening system Improper ink water balance Excessive printing pressure Glazed blanket ink rollers or dampening rollers Ink rollers overheated Improper ink tack viscosity ratio Solution 1 Desensitize or remake plate adjust plate making process Adjust fountain solution concentration to proper level Adjust to proper ink water balance Reduce printing pressure to proper levels Clean blanket and rollers thoroughly and recondition per manufacturer specifications Check for worn bearings and replace if necessary adjust ink rollers to proper pressure Consult ink manufacturer FlintGroup Web Offset Heatset Troubleshooting Guide Tinting Toning Symptom Emulsified ink transferred to printed sheets as background tint Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 Ink bleeds into fountain solution Improper conc
18. t Troubleshooting Guide Mottle Symptom Solids areas not uniform resulting in uneven appearance Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1e NDNA Non uniform stock surface Improperly set or worn ink form rollers Excessive linting Printing pressure too high Worn blanket Improper ink water balance Poor ink transfer Solution 1 N OOT AO Consult paper manufacturer to change stock consult ink manufacturer for ink with less penetration Adjust rollers to proper settings replace if necessary See PICKING LINTING Reduce printing pressure Replace blanket Adjust to proper ink water balance Consult ink manufacturer a Flint Group Web Offset Heatset Troubleshooting Guide Picking Linting Symptom Picking Lifting of the coating from coated stocks onto plates blankets and or ink train rollers Linting Accumulation of fibers from uncoated stocks onto plates blankets and or ink train rollers Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 2 3 Too much water reaching paper Improper concentration of fountain solution Excessive lint surface trash coating dust on stock Base stock picks Improperly packed cylinders pressure too high for ink stock combination B
19. tion Consult paper manufacturer change stock if necessary Consult ink manufacturer to adjust pigment strength Flint Group Web Offset Heatset Troubleshooting Guide Blocking Symptom Undesired adhesion between printed materials Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Cause 1 2 Ink dries too slowly Improper silicone applicator setting Excessive pressure on log or in stack Solution 1 2 See DRYING Check concentration and reduce film thickness Reduce strap pressure or reduce stack height FlintGroup Web Offset Heatset Troubleshooting Guide Color Variation Symptom Inconsistent color reproduction between proof and print Cause 1 Variation between proof and printing substrates 2 Special spot color does not match proof 3 Excessive heat causes too much penetration of ink resin poor gloss Ask about gt Flexography gt Pub Gravure gt Pkg Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink HOME Solution 1 Adjust ink film thickness to that of proof consult substrate manufacturer for stock more similar to proof stock consult ink manufacturer for ink with hue and hold out adjusted for current paper Consult ink manufacturer Reduce drier temperature increase press speed FlintGroup Web Offset Heatset Troubleshooting Guide Dot
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