Flexography Troubleshooting Guide
Contents
1. Group Flexography Troubleshooting Guide Mottle Problem Random light and dark spots May cause color to appear dirty Cause 1 Substrate has non uniform caliper or absorption characteristics 2 Ink viscosity too low 3 Improper impression Can be caused by uneven plates surface dirt on plates or dirty impression cylinder 4 Non optimal plate selection 5 Contaminated plates 6 Transparent color gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Solution 1 Try lower durometer plate try opaque ink Add fresh ink and maintain proper viscosity Clean plates and impression cylinder adjust impression check and adjust plate cushion or mounting materials remake plates Consult plate manufacturer Wash plates with appropriate solvent or replace plate if cannot be cleaned Transparent color does not cause problem but increasing opacity of the color match may mask the problem Flint Group Flexography Troubleshooting Guide Pinholes or Fisheyes Problem Tiny round voids in printed image Sometimes confused with screening Slide 1 of 2 Cause 1 gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Ink drying too fast Low or uneven treatment level on film Excessive foam Solvent Flexo Contaminated film surface Solution 1 Check air flow a2. ink Solution 1 Mix and keep mixing while using Agitation in sump may be required in severe Cases NOTE All inks should be mixed before use as a general practice Flint Group Flexography Troubleshooting Guide Foaming Problem Voids in printing foam visible in sumps or ink overflowing sump gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause 1 2 Too much air being introduced into ink Ink level in fountain below pump intake level Ink falls excessive distance when recycled into reservoir Ink viscosity too high Improperly formulated ink Water Flexo Poor cleanup procedures Solution 1 Check for leaks in hoses and pumps Adjust pump speed to reduce agitation Fill fountain with ink well above intake level Use hose or pipe to eliminate long ink falls into pan Reduce viscosity to allow any bubbles to rise and break at surface Consult your ink manufacturer Water Flexo Ensure that no detergent from clean up has contaminated ink FlintGroup Flexography Troubleshooting Guide Ghosting Problem Part of image not printing resembles an offset of same image See also Tracking gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause A Ink dries too fast for anilox volume does not adequately replenish anilox Sol
3. or on sheetfed presses Cause Solution 1 Ink build up on delivery belt 1 Clean belts 2 Worn belts 2 Replace belts 3 Mechanical problems 3 Ensure all tensions pressures and other mechanical adjustments are correct 4 Inappropriate ink formulation 4 Consult your ink manufacturer gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset ane nk FlintGroup gt HOME Flexography Troubleshooting Guide Smearing Problem Ink smeared into non image area by surface contact down line on the printing press Cause Solution 1 Too much ink 1 Use a lower volume anilox increase nip pressure 2 roll lower viscosity 2 Too little drying 2 Increase dry capacity slow down press use faster reducer 3 Rewetting by adhesive or coating 3 Change ink coating reducer or formulation 4 Mechanical speed mismatch 4 Adjust combination of plate mounting tape and gearing gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink F lint Gr OUP gt HOME Flexography Troubleshooting Guide Striations Problem Lines of weak ink or no ink in direction of print run Cause Solution 1 Ink film too thin due to worn or 1 Clean or replace anilox roller remake plugged anilox roller high durometer plate check and adjust pH and plate or too low viscosity viscosity 2 Improper pressure setting on 2 Adjust impression to as near kiss as
4. substrate porosity or surface treatment Previously used ink Inadequate amount of ink in fountain or doctor blade chamber Different suppliers of same color 6 Variation in ink batches 7 Non standard process design Solution 1 Establish set procedures for viscosity control Water Flexo Maintain proper pH Consult with ink and substrate manufacturers for proper measures to be taken Replace or add virgin ink Add ink to fountain or ensure adequate ink pressure into enclosed doctor blade assembly Run only one supplier s ink on a given color Consult your ink manufacturer Inks must be modified to matched print station recommend match visual standard on site FlintGroup Flexography Troubleshooting Guide Dirty Printing Problem Fuzzy extensions of image into non image area Impression increase or change in plate durometer during run Recovers when taken off press sometimes results in cracks in plate during storage Solution Cause iP 2 O 00 AO O ae ee gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Excess ink being applied to plate Excess impression between plate and substrate Ink viscosity too high Accumulation of paper dust lint Ink drying too fast Water Flexo Ink pH too low Excessive anilox volume Excess anilox impression Plate swell caused by use of materials not compatible with printing plates 1
5. Adjust anilox fountain roller impression adjust doctor blade pressure Reduce to kiss impression for type and minimize impression consistent with acceptable printability for reverses 3 Adjust to lowest viscosity consistent with acceptable oo printability Improve housekeeping vacuum paper dust and filter ink Check air flow at between deck driers consult your technical service representative Solvent Flexo Use slower solvent blend to reduce ink Water Flexo Raise pH as instructed to by ink manufacturer Use lower volume anilox Back off impression of anilox to plate Confer with plate and ink suppliers FlintGroup Flexography Troubleshooting Guide Excessive Ink Consumption Problem Too few impressions per pound of ink gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause A a Ink viscosity too high Ink color acceptable but stronger than standard Weak ink Excessive anilox volume 2 Roll Soft metering roller Excess loss on start up or shutdown Solution 1 gi Reduce ink to lowest viscosity consistent with acceptable printability Use balanced extender to weaken color to the middle of the acceptable range Check ink for strength vs original standard Finer shallower anilox Check durometer extend or reduce ink Additional care in ink handling can be due to large amount of ink required for inking st
6. Flexography Troubleshooting Guide gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Adhesion gt Bleed gt Blushing Hazing Fogging gt Color Too Strong gt Color Variations Among Same Color Jobs Being Run InA Plant gt Dirty Printing gt Excessive Ink Consumption gt Fill in of Reverses and Type gt Float on Ink gt Foaming gt Ghosting gt Halo Around Print gt Kick out gt Mottle gt Pinholes or Fisheyes gt Screening gt Set off and or Blocking gt Settling of Ink gt Sheet Feeding Problem gt Smearing gt Striations gt Tracking gt Trapping gt Weak Color Flint Group Flexography Troubleshooting Guide Adhesion Problem Ink flakes off substrate comes off when crinkled or is removed easily in tape test Cause gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME 1 a ROON Viscosity too high Viscosity too low Ink surface tension too high Incorrect ink system for substrate Poor film treatment Ink drying too slow Substrate surface contamination Insufficient web temperature Solution Ik Pe Reduce viscosity consistent with acceptable printability Add virgin ink to fountain Consult your technical sales representative Ensure that the correct ink for the substrate is being used C
7. ation FlintGroup Flexography Troubleshooting Guide Fill in of Reverses and Type Problem Ink bridges across small print and non printing gaps in design gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause 1 Excess ink being applied to plate 2 Excess impression between plate and substrate 3 Ink viscosity too high 4 Accumulation of paper dust lint 5 Ink drying too fast Water Flexo Ink pH too low Excessive anilox volume Solution 1 Adjust anilox fountain roller impression adjust doctor blade pressure Reduce to kiss impression for type and minimize impression consistent with acceptable printability for reverses Adjust to lowest viscosity consistent with acceptable printability Improve housekeeping vacuum paper dust and filter ink Check air flow at between deck driers Consult your ink manufacturer Solvent Flexo Use slower solvent blend to reduce ink Water Flexo Raise pH as instructed by ink manufacturer Use lower volume anilox FlintGroup Flexography Troubleshooting Guide Float on Ink Problem Non uniform layer on surface of ink in container may result in a variety of print defects as container is used gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause de Non compatible additive that is less dense than
8. cceptable printability consult your ink manufacturer Reduce rewind tension Avoid excessive pressure in rewind apply offset powder to web prior to rewind overprint with non blocking clear varnish if necessary Avoid excessive pressure in rewind apply offset powder to web prior to rewind overprint with non blocking clear varnish consult your ink manufacturer for different ink Reduce web temperature by chilling within 10 F of ambient temperature Avoid over chilling which allows condensation to form on film surface Solvent Flexo Check driers for heat and airflow consult your ink manufacturer Water Flexo Check driers for heat and airflow consult your ink manufacturer e FlintGroup Flexography Troubleshooting Guide Settling of Ink Problem Thick or particulate material in bottom of Ssumps pans or ink containers Cause I 2 3 gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Old ink Press return at lower viscosity Improper ink formulation Some specialty inks may settle due to the high specific gravity of the pigment Solution 1 2 3 Rotate inventory Mix then combine with virgin ink prior to use Consult your ink manufacturer Add agitation to the ink sump FlintGroup Flexography Troubleshooting Guide Sheet Feeding Problem Problem Slipping in delivery belts causing frequent jams in subsequent operations
9. e Trapp ing Problem Cannot achieve good coverage in areas where more than one color is applied gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause 1 First down color drying too slow 2 Subsequent colors drying too fast 3 Improper pressure setting on impression cylinder 4 Water Flexo Improper viscosity 5 Incorrect plate or backing Solution 1 Consult your ink manufacturer check drier capacity Solvent Flexo Use faster drying reducing solvent Check air flow in between color driers Consult your ink manufacturer Solvent Flexo Use slower drying reducing solvent Adjust impression on first and second down inks Water Flexo In general each succeeding color requires slightly higher viscosity adjust accordingly Use optimal plate firmer backing FlintGroup Flexography Troubleshooting Guide Weak Color Problem Visual color different from standard Slide 1 of 2 Cause 1 Ink viscosity too low Solvent Water Flexo a Too much solvent added to cut ink b Excess clean up solvent in system Water Flexo pH too low 2 Worn anilox roller 3 Plugged anilox roller gt Flexography gt Publication Gravure 4 Plate durometer too high gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Solution Replace ink totally or add virgin ink to fountain Consult anilox roller manufacturer to veri
10. exo Use less hygroscopic solvent blend for ink reduction coordinate with your ink manufacturer Flint Group Flexography Troubleshooting Guide Color Too Strong Problem Visual color different from standard gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause Solution 1 Solvent Flexo Ink viscosity too high 1 Water Flexo Ink pH too high 2 Ink pigmentation too high 2 3 Inappropriate anilox roll cell volume 3 too great or cell count too low 4 Inadequate pressure setting on 4 impression roll 5 Plate and or ink metering roll 5 durometer too low 6 Inadequate impression on doctor 6 blade Solvent Flexo Reduce viscosity to proper level with recommended solvent blend Water Flexo Check and adjust pH then reduce viscosity to proper level Reduce ink colorant strength with balanced extender Replace anilox roller with one of higher line count and or lower volume capacity Adjust impression for optimum printability Consult plate and or roller manufacturer Adjust doctor blade to recommended pressure FlintGroup Flexography Troubleshooting Guide Color Variations Among Same Color Jobs Being Run in a Plant Cause 1 gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Poor viscosity control Water Flexo Lack of pH control Variation in
11. fy replace if necessary Use brass bristled brush for chrome rollers stainless steel bristled brush for ceramic rollers Solvent Flexo Clean with recommended solvent to remove dry ink from cells Water Flexo Clean with brush hot water 140 F and detergent to remove dry ink from cells Remake plates to proper specifications and replace continued Flin Group Flexography Troubleshooting Guide Weak Color continued Problem Visual color different from standard Slide 2 of 2 Cause 5 Improper pressure setting on impression and or anilox roller 6 Ink too weak for anilox roller volume 7 Inadequate ink in fountain or in doctor blade chamber 8 Solvent Flexo Dirty plates 9 Water Flexo Glazed or dirty gt Flexography plates gt Publication Gravure gt Sheetfed Offset 10 Water Flexo Glazed metering roll gt UV gt Web Offset gt News Ink gt HOME Solution 5 Re adjust impression for optimum printability 6 Consult your ink manufacturer to strengthen ink if at all possible If this is not possible replace anilox roller with one having a deeper etch 7 Add ink to fountain or ensure adequate ink pressure into enclosed doctor blade assembly 8 Solvent Flexo Wash plates with recommended solvent and if necessary a moderately stiff non metallic brush 9 Water Flexo Wash plates with warm water a mild detergent and a moderately stiff non metallic brush 10 Water Flexo Wash wi
12. heck surface of film for adequate treatment treat in line if possible Check driers for heat and airflow consult your ink manufacturer Solvent Flexo Reduce with faster solvent blend Check with film supplier as to advisability of applying a primer before printing use in line treater Increase temperature settings of driers check drier balance FlintGroup Flexography Troubleshooting Guide Bleed Problem Color spreads into subsequently applied coating or adhesive Cause 1 Improper pigment use in ink formulation 2 Coating or adhesive may be rewetting the dried ink gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Solution 1 Consult your ink manufacturer to reformulate using resistant pigment 2 Consult your ink manufacturer to reformulate using resistant pigment Flint Group Flexography Troubleshooting Guide Blushing Hazing Fogging Problem Milky foggy or matte appearance in an ink or coating Cause 1 Solvent Flexo High humidity Causing excess moisture build up in ink 2 Solvent Flexo Moisture condensation on surface of drying ink gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Solution 1 Solvent Flexo Consult your ink manufacturer for properly balanced solvent blend for specific ink and printing conditions Solvent Fl
13. impression cylinder and or anilox possible roller due to uneven plates or substrate 3 Defects in anilox plate or fountain 3 Replace or repair defective component roll investigate cause to avoid recurrence 4 Ink too transparent 4 Transparent color does not cause problem but increasing opacity of the color match may mask the problem gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset b News ink FlintGroup gt HOME Flexography Troubleshooting Guide Tracking Problem Ink appears in area where there is no print See Ghosting gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause Solution 1 Ink film too heavy 1 2 Ink drying too slow 2 3 Mechanical problems 3 4 Difficult design due to extreme 4 color coverage degree of trapping and or die cut positioning Reduce viscosity consistent with acceptable color and printability have ink reformulated for stronger color to permit thinner film adjust to proper pressure at all roller nips Solvent Flexo Adjust ink drying speed with supplier recommended solvent blend Water Flexo Adjust ink drying speed based on instructions from supplier Adjust and clean all belt and idler roller surfaces that are in contact with the printed substrate Change layout of design and or consult your ink manufacturer FlintGroup Flexography Troubleshooting Guid
14. t between deck driers consult your ink manufacturer 2 Check film treatment re treat or treat in line if possible 3 See FOAMING Solvent Flexo Check with film supplier about applying a wash coat before printing replace with roll of film from different lot gt NOTE Pinholes generally pertain to unwetted substrates Fisheyes are areas where ink has pulled back leaving uninked or light areas Flint Group Flexography Troubleshooting Guide Pinholes or Fisheyes continued Problem Tiny round voids in printed image Sometimes confused with screening Slide 2 of 2 Cause 5 Solvent Flexo Contamination from poor clean up of fountain rollers etc 6 Solvent Flexo Excess slip agent in ink 7 Solvent Flexo Incorrect ink for substrate being printed 8 Water Flexo Excessive defoamer gt Flexography aa gt Publication Gravure 9 Water Flexo Ink surface tension gt Sheetfed Offset too high gt UV gt Web Offset gt News Ink gt HOME Solution 5 Solvent Flexo Empty fountain properly dispose of contaminated ink clean fountain and all rollers properly and start job with fresh ink Solvent Flexo Clean up as described in number 5 above and start up with ink from a different lot consult your ink manufacturer Solvent Flexo Consult your ink manufacturer Water Flexo Add fresh ink to fountain or replace all ink in fountain with fresh ink Water Flexo Consult your ink man
15. th warm water a mild detergent and a moderately stiff non metallic m FlintGroup
16. ufacturer for recommendation FlintGroup Flexography Troubleshooting Guide Screening Problem Small voids printed in image area Often has very regular shape consistent with anilox pattern Cause Solution 1 Ink drying too fast on anilox roll 1 Consult ink manufacturer Solvent Flexo Reduce with slower solvent blend 2 Inadequate inking of anilox 2 Slow down press increase ink flow or starvation slow return to increase ink level in fountain 3 Similar appearance can be caused 3 Consult ink manufacturer or plate by plates or backing manufacturer gt Flexography gt Publication j Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink F lint Gr OUP gt HOME Flexography Troubleshooting Guide Set off and or Blocking Problem Ink transfers from image side to back side of substrate when unrolled inability to separate printed sheets or to unroll web Solution Cause 1 2 3 on gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Drying too slow Excess pressure in re wound roll Film substrate treated on both sides Film substrate heavily plasticized Web too warm when rewound Web rewound with too much surface moisture Solvent Flexo Trapped solvent in printed ink film Water Flexo Trapped amine in printed ink film 1 Check driers for heat and air flow reduce ink viscosity consistent with a
17. ution 1 e Slow ink down e Add extender e Use coarser anilox e Reduce press speed FlintGroup Flexography Troubleshooting Guide Halo Around Print Problem Area just inside of printed image with light or no ink often accompanied by dirty printing gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause de Improper pressure settings on impression Solution 1 Adjust to as close to kiss impression as possible consistent with acceptable printability FlintGroup Flexography Troubleshooting Guide Kick out Problem Coagulated ink lumps or particles in ink gt Flexography gt Publication Gravure gt Sheetfed Offset gt UV gt Web Offset gt News Ink gt HOME Cause 1 Solvent Flexo Incorrect solvent balance during viscosity reduction 2 Solvent Flexo High humidity Causing excess moisture build up in ink 3 Water Flexo Drop in pH 4 Mixing incompatible inks Solution 1 Solvent Flexo Consult with your ink manufacturer for properly balanced solvent blend for specific ink and printing conditions Solvent Flexo Use less hygroscopic solvent blend for ink reduction Coordinate this with your ink manufacturer Water Flexo Adjust pH to proper level with amine solution Consult your ink manufacturer Do not mix inks from different vendors or water inks with solvent inks Flin
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