10. Troubleshooting
Contents
1. gt Excessive air circulation draught in the spray area gt Products too cold Solutions gt Sand down the defective surface gt Remedy defects as described gt If necessary change to slower acting thinner Pin holing Possible causes gt Insufficient and excessively dry spraying of the substrate gt Excessive application at high temperature or on heated substrate gt Porous substrate fibreboard particleboard etc gt Incorrect thinning Solutions gt Rub down the defective surface gt Check viscosity of the coating gt If necessary use a slower thinner gt Introduce other changes measures to inhibit pin holing Sagging on edges Possible causes gt Excessive amount applied gt Too slow thinner gt Too low viscosity gt Incorrect angle of the gun automatic spray machine Solutions gt Apply lower amount gt Change to a faster thinner gt Increase viscosity gt Change the angle of the gun Striping Possible causes gt Defective or dirty air or fluid nozzle gt Incorrect gun settings gt Conveyor speed and the guns transversal speed not synchronized 10 1 2 Curtain coating Solutions gt Check and clean the nozzles gt Check the spray gun positions and spray fan gt Synchronize conveyor and transversal speed Blue corners Possible causes gt Edges too sharp gt Viscosity too low gt Corners sanded through when sanding primer Solut2. 10 Troubleshooting Finding a defect on a coated surface is fairly easy but finding its cause might not be In our experience most finishing problems emanate from varia tions in the process not the product First if you have a documented finishing system check that you are following it and if the problem remains then check each step of the process again There are many parameters that influence the finishing process and you need to verify each one of them one at a time unless the origin of the problem is obvious This involves locating the step in the process from where the problem originates and normally the easiest way of doing this is to follow the process backwards When you find the step in the process that is causing the problem for example the drying application or sanding step use Facts on finishing to help you solve the problem 10 1 Application problems 54 10 1 1 Spraying 10 1 2 Curtain coating 10 1 3 Roller coating 10 1 4 Printing 10 2 Drying curing problems 59 10 2 1 Air drying 10 2 2 Forced drying 10 2 3 UV curing 10 Troubleshooting 10 1 Application problems 10 1 1 Spraying Blue corners Possible causes gt Edges too sharp gt Viscosity too low gt Corners sanded through when sanding primer Solutions gt Increase the radius of the corner either by denibber or in the woodworking process gt Increase viscosity gt Usea less coarse sandpaper when sanding t
3. Solution gt Improve sanding gt Check UV energy and peak gt Check application amount Scratch sensitive surface Possible cause gt Poor curing gt Application amount too low gt Incorrect product for this application Solution gt Check UV energy and peak gt Check application amount gt Contact Becker Acroma 2007 Becker Acroma All rights reserved This material may not be reproduced displayed modified or distributed in whole or in part without the express prior written permission of the copyright holder Beckers Becker Acroma Becker Acroma Group AB Industrigatan 5 P O Box 2016 SE 195 02 M rsta Sweden Phone 46 381 261 00 Fax 46 381 261 98 info beckeracroma com www beckeracroma com Australia BeNeLux Belarus Bulgaria Canada China Czech Republic Denmark Estonia Finland France Germany Great Britain Hungary Iceland Indonesia Ireland Israel Italy Latvia Lithuania Malaysia New Zealand Norway Philippines Poland Portugal Romania Russia Slovakia Slovenia Croatia Spain Sweden Switzerland Taiwan Thailand Turkey Ukraine USA Vietnam Production bkcsthlm com
4. Poor or no sanding between coating layers gt Too much time has passed between sanding and lacquering gt Coating dry sprayed gt Too much catalyst used gt Some foils and plastics are unsuitable for coating or require sanding before application gt Poor combination of coating system Some water based coatings have poor adhesion to other types of coatings Solution gt Check that sealer basecoat is properly sanded before applying the next layer gt Sand the surface lightly again gt Try to spray a full wet layer change toa slower thinner gt Ensure that the amount of catalyst is correct gt Sand the foil thoroughly change foil or apply special adhesion sealer gt Contact Becker Acroma 10 Troubleshooting Soft film Poor drying Possible cause gt The coating is not fully cured because of too low temperature or too short drying cycle gt Temperature too low during overnight drying gt Incorrect quantity of hardener used gt Hardener affected by moisture PU coatings 10 2 2 Forced drying Solution gt Check temperature gt Extend the drying time gt Check that the temperature does not drop during after work hours if drying over night gt Ensure that correct amount of hardener is used gt Change hardener PU coatings always keep hardener container closed Blocking Possible cause gt Surface temperature too high when stacking Too short drying cycle Tempe
5. Troubleshooting Mud cracking Possible cause gt Coating skins over before most of the water has evaporated out from the film gt Too much coating applied Poor adhesion Peeling Possible cause gt Poor or no sanding between coating layers gt Too much time has passed between sanding and lacquering gt Coating dry sprayed gt Too much catalyst used gt Some foils and plastics are unsuitable for coating or require sanding before application gt Poor combination of coating system Some water based coatings have poor adhesion to other types of coatings Solution gt Decrease air velocity in flash off section gt Apply less coating gt Contact Becker Acroma Solution gt Check that sealer basecoat is properly sanded before applying the next layer gt Sand the surface lightly again gt Try to spray a full wet layer change to a slower thinner gt Ensure that the amount of catalyst is correct gt Sand the foil thoroughly change foil or apply special adhesion sealer gt Contact Becker Acroma Resin Sap migration Possible cause gt Resinous wood suchas pine is dried at too high temperature 10 2 3 UV curing Odour Possible cause gt UV coating not fully cured Solution gt Decrease oven temperature and IR energies so the surface temperature of the substrate stays below 45 C during the drying process Solution gt Check energy and peak values of the UV lamps Colo
6. e sure the temperature of the inks are OK and that ink used to refill the machine is at the same temperature gt Check the surface temperature of the substrate prior to printing gt Measure the UV lamps and ensure the energy and peak values are within prescribed specifications 10 Troubleshooting 10 2 Drying curing problems 10 2 1 Air drying Blushing Possible cause gt Humid environment in combination with fast thinners gt Water not fully evaporated in water based UV coatings gt Extreme amounts of micro bubbles Solution gt Change toa slower thinner and if possible try to increase air temperature gt Change drying setup Increase either time air velocity or temperature gt See chapter on micro bubbles in the section on Spraying Bubble formation Possible cause gt Air from the substrate Solution gt Change toa slower thinner Cracking Possible cause gt Too low temperature when drying water based coatings gt Too high amount of hardener in acid cured systems Solution gt Sand down the surface and re coat gt Check mixing instructions gt Check drying conditions Mud cracking Possible cause gt Too much air movement when drying water based coatings gt Excessive application amount water based coatings Solution gt Try to minimize air movement in the drying area gt Reduce the applied amount Poor adhesion Peeling Possible cause gt
7. g flow pump as smooth as possible with little or no turbulence gt Make sure there is no leakage in the pump could inject air into the coating gt Try to remove foam and bubbles for example a nylon stocking can act as a filter if it is placed on the return outlet gt Contact Becker Acroma Ghost image of previous panel Possible cause gt Application roller does not re wet to the same level as for the previous panel Solution gt Apply scraper to the application roller gt Contact Becker Acroma 10 Troubleshooting Line formation crosswise Possible cause Solution gt Different speed on conveyor and application roller gt Check application roller and conveyor gt Damaged application roller speed rollers must be clean gt Too high down pressure on application roller gt See if you can see any damaged in gt Pressure between doctor and the application roller Use less down pressure Release pressure between rollers Slow down reversing doctor roller Increase the pump pressure Change bearings Ghost image of previous panel see above application roller too high gt Doctor roller running reverse at too high speed gt Not enough material between rollers when running doctor roller reverse gt The bearings in either rollers or conveyor are damaged v v v v v v Line formation lengthwise Possible cause gt Damaged scraper on doctor roller or in case of a Light filler machine
8. he primer Bubble formation Possible causes gt Air from the substrate gt Incorrect thinner Solutions gt Lower viscosity gt Slower thinner Craters Fisheyes Possible causes gt Substrate contaminated by silicone or oil gt Compressed air contaminated by water or oil Solutions gt Locate the contaminating source lubrication of woodworking equipment compressed air system lotions ventilation seals gt Contact Becker Acroma for advice Lifting Wrinkling Possible causes gt Excessive layer of topcoat applied gt Topcoat applied before underlying layer is fully cured gt Unsuitable combination of primer and topcoat can also apply to pre treated substrate gt The products have been stacked too closely during drying or the air circulation in the drying area was inadequate gt Incorrect amount of hardener Solutions gt Rub down to clean wood surface gt Contact Becker Acroma if unable to determine the cause of the defect Micro bubbles Possible causes gt Incorrect thinner gt Leakage in the spray gun channels or in the suction hose of the pump Solutions gt Change thinner gt Check equipment 10 Troubleshooting Orange Peel Possible causes gt Too high viscosity gt Incorrect thinner gt Excessive temperature difference between substrate and coating gt Incorrect air fluid pressure when spraying or incorrect distance from gun to substrate
9. ions gt Increase the radius of the corner either by denibber or in the woodworking process gt Increase viscosity gt Use a less coarse sandpaper when sanding the primer 10 Troubleshooting Grey dotted patterns Possible cause gt Electrostatic charged panels Solutions gt Connect all machines to each other with a copper cable gt Electrically earth all machines gt Install de ionizing equipment before the curtain coater Gloss and tone variations Possible causes gt The jaws of the curtain coater are not parallel applied amount uneven gt The curtain is moving forward and backwards when coating which results in an uneven application amount Sagging on edges Possible cause gt Too high conveyor speed gt Coating thinner not optimal Splitting of curtain Possible cause gt Air bubbles in the coating gt Coating has incorrect surface tension or rheology 10 1 3 Roller coating Solution gt Adjust the jaws so they are parallel gt Shield the curtain from air movements Solutions gt Decrease the conveyor speed gt Contact Becker Acroma Solutions gt Reduce the height of the curtain gt Check that the paint groove is in place inside the curtain head gt Check that the splash plate is in place in the return tank gt Ensure that the head is fully filled with coating material and that you have a steady flow from the heads overflow valve gt Try to make the coatin
10. rature in ovens too low Cooling section not working Too much coating applied UV oven not working properly water based UV coatings gt Hardener amount too low vwovrvwyy Solution gt If possible cool the surface before stacking gt Stack lower gt Increase drying cycle gt Increase the temperature in the ovens gt Check that the cooling section is working gt Check the application amount gt Check the energy and peak values of the UV oven gt Ensure that the amount of hardener is correct Blushing Possible cause gt Water not fully evaporated in water based UV coa tings Solution gt Increase oven temperatures air velocity and drying time gt Apply less coating Bubble formation Possible cause gt Too much IR energy gt Too high temperature in ovens Solution gt Decrease the IR energy gt Decrease the temperature in the ovens gt Increase the temperature in the flash off section Matt patches Possible cause gt Bubbles that have burst too late leave matt patches Mostly common when using a curtain coater Solution gt Try to minimize bubble formation in the curtain coater gt Change to a slower thinner gt Contact Becker Acroma Micro bubbles Possible cause gt See chapter about spraying gt Too much IR energy Solution gt See chapter about spraying gt Decrease the IR energy gt Increase the temperature in the flash off section 10
11. speed of doctor roller 10 Troubleshooting Stain colour too dark or too light Possible cause gt Too hard light or soft dark stain roller gt Wood sanding too fine light or too coarse dark Uncoated patches Possible cause gt Poor calibration of substrate 10 1 4 Printing Solution gt If possible change stain roller gt Check the wood sanding process gt Contact Becker Acroma Solution gt Improve calibration gt Change to softer application rollers gt Check the application rollers pressure to the substrate Unsharp print picture Possible cause gt Synchronization between print rollers off gt Viscosity incorrect gt Basecoat layer not smooth enough gt Too high pressure of application roller to the substrate Solution gt Check synchronization gt Check the viscosity of the inks gt Ensure that correct amount of basecoat is applied gt Release the pressure of the application roller on the substrate Weak print Possible cause gt Viscosity incorrect gt Incorrect substrate temperature high or low Colour drifting Possible cause gt Incorrect viscosity gt Incorrect temperature of the inks gt Surface temperature not correct gt Poor UV curing of previous layer base coat and or inks Solution gt Check the viscosity of the inks gt Check the surface temperature of the substrate prior printing Solution gt Check viscosity gt Mak
12. the scraper of the smoothing roller gt Damaged application roller gt The protective shutter in the UV oven is set too low in feed gt Ghost image of previous panel see previous paragraph Rough patches when using Light filler machine SAS Possible cause Solution gt Too much variation of the substrate thickness gt Calibrate substrate Smoothing roller can not reach low spots gt Check the sanding process gt Oversanding if it is along the edges of the substra gt Check application amount te Smoothing roller cannot reach rounded edges gt Application amount too low when using Opti roller Rough surface Possible cause Solution gt Applied amount not correct can be either too little gt Lower application amount or too much gt Change product gt Viscosity of coating too high for this application gt Change to harder application roller gt Too soft application roller Scrape marks and lip formation in front or end of panel Possible cause Solution gt The speed of the application roller and conveyor gt Adjust the speed of the application roller belt is not synchronized gt Decrease the speed of the smoothing roller gt Smoothing roller running too fast or at and or release pressure too high pressure gt Decrease application amount in Light filler gt Too much material applied before smoothing machine by pressing doctor and application roller when filling together or change
13. ur Possible cause gt Some UV lacquers might turn yellow when curing gt Incorrect type of stain used underneath the UV coating gt Incorrect application amount gt Different quality or producer of the substrate com pared to the time of setup Solution gt Change toa different product gt Wait some initial yellowing vanishes after one hour gt Check the applied amount gt Compare original substrate with present and either change back or re match the colour 10 Troubleshooting Gloss low high Possible cause gt Thin layer of topcoat gives lower gloss gt Thick layer of topcoat gives higher gloss gt Ifthe UV energy and peak of first the UV lamp is low then the gloss will be low gt High surface temperature of the substrate gives lower gloss gt Poor curing of the previous coat can influence the gloss up or down Solution gt Change the application amount gt Change the energy and or the height of the first lamp gt Try to lower the surface temperature Turn off lamps in the previous ovens but ensure that power is efficient gt Check the energy of all UV lamps in the line Haze Possible cause gt Poor curing might show up as a haze weeks after application Solution gt Check UV energy and peak regularly Poor adhesion Peeling Possible cause gt Poor sanding gt Poor curing gt Too good curing of previous layer gt Application amount too high
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