Quick Troubleshooting Guide For Flexographic & Rotogravure Printing Defects:

1. Marbled print, speckled or speckled appearance of the print, colored or black circles, most often appearing in light colors.

SR CAUSE REMEDY
1 Viscosity too low Add undiluted ink and adjust the viscosity. Change the photo. Add thickener.
2 Poor surface condition of the photo.
Pollution of the photo (anti-foam, silicone, …)		 Thoroughly clean the plates, do not use materials likely to leave lint on the plate.
3 Poor condition of the bubbler or anilox. Check the condition of the bubbler, the wear of the anilox cylinder, make sure that the cells are not blocked.
4 Ink absorption unevenly in the support. Use softer shots, or opaque inks.
Change media.

2. The ink dries on the inking system (plate and cylinder) and hampers ink transfer. 

SR CAUSE REMEDY
1 Solvent-based ink: the diluting solvent evaporates too quickly. Use a slower evaporating solvent (retarder).
2 Water based ink: incorrect pH. Add 2-3% retarder. Add regenerator (1 to 2% every 3/4 hour).

3. Drying too slow, tearing off the ink or smearing of the bar feeders. reel blocking, sticky ink.

SR CAUSE REMEDY
1 Solvent-based ink: ink viscosity too high. Use a slower evapor Reduce the viscosity with the recommended solvent.
2 Too slow evaporation of the dilution solvent Use a faster evaporating solvent.
3 Water based ink: viscosity too high. Dilute with water or viscosity reducer (2 to 5%). Incorporate regenerator (1 to 2%).

4. Poor adhesion of the ink to the support, poor mechanical strength (crumpling, adhesive tape, scratching, etc.

SR CAUSE REMEDY
1 Drying box problem. Check temperature and extraction.
2 Ink not suitable for the medium. Use suitable ink or consult the supplier.
3 Bad treatment of the support or outdated treatment. Check the surface tension of the support or consult the supplier for the validity of the treatment. Check the appropriateness of applying a pre-lacquer varnish or primer or treating CORONA.
4 Insufficient drying. Increase the drying temperature and if possible the air flow.

5. Impression of intensity too low

SR CAUSE REMEDY
1 Viscosity too low. Add undiluted ink or a concentrate.
2 Anilox frame too fine. Use an anilox with a larger weft.
3 Wear or blockage of the anilox frame. Clean or change the anilox.

6. Too intense impression

SR CAUSE REMEDY
1 Viscosity too high. Decrease viscosity with the appropriate thinner.
2 Anilox weft too large. Choose an anilox with finer weft.
3 Wrong squeegee setting. Adjust the squeegee to properly wipe the cylinder
4 Color strength too high. Reduce the intensity with the appropriate bleach.

7. Poor ink transfer, the plate does not deposit enough ink on the support.

SR CAUSE REMEDY
1 Viscosity too low, drying on the plate. Add undiluted ink. Adjust the ink drying.
2 Surface tension of the support too low or surface tension of the plate too high. Check the treatment of the support and the surface energy of the plate.
3 Incorrect adjustment of the pressure between the radiograph and the anilox. Adjust the settings.
4 Wear or blockage of the anilox frame. Change or clean the anilox.
5 Anilox frame too fine. Use a larger weft.

8. Poor ink transfer, the plate does not deposit enough ink on the support. 

SR CAUSE REMEDY
1 Viscosity too low, drying on the plate. Add undiluted ink. Adjust the ink drying.
2 Surface tension of the support too low or surface tension of the plate too high. Check the treatment of the support and the surface energy of the plate.
3 Incorrect adjustment of the pressure between the radiograph and the anilox. Adjust the settings.
4 Wear or blockage of the anilox frame. Change or clean the anilox.
5 Anilox frame too fine. Use a larger weft.

9. Increase in viscosity in the inkwell / duct

SR CAUSE REMEDY
1 Solvent-based ink: unsuitable solvent or imbalance due to evaporation Add undiluted ink. Adjust the ink drying.
2 Water-based ink: decrease in pH. Add regenerator (1 to 2%).

10. Blurring of Four Color Print

SR CAUSE REMEDY
1 Poor relationship between the screen size and that of the anilox Select an anilox suitable for the work to be performed. In flexo the ratio between the frame of the plate and that of the anilox must be from 1 to 3.5 or even 4
2 Wrong angle of the screen frames Selection films must be corrected.

11. Blocking in reel, adhesion of the turns between them making the prints unusable, transfer of the front printing on the back of the support. 

SR CAUSE REMEDY
1 Poor ink drying. Reduce the viscosity of the ink. Change the dilution solvent to speed up drying. Change the proportion of the dilution solvent, Increase the drying capacity and / or the air volume.
2 Rewind too tight. Reduce the rewind tension.

12. Excess ink around halftone dots and small text and poor character definition. 

SR CAUSE REMEDY
1 Excess pressure between the radiograph and the anilox. Set the pressure correctly
2 Ink drying too fast Adjust the ink drying.
3 Viscosity too high Decrease viscosity.

13. Streaks, large transverse lines on the print.

SR CAUSE REMEDY
1 Worn gear Replace worn gears.
2 Over-tightening of the ink cylinder. Over-tightening of the ink cylinder.
3 Viscosity too high Decrease viscosity.