Printing Flaws

Flexographic Plates Troubleshooting: Problems, Causes and Solution – Part 2

This is a continuation to the series of article part 1 on flexo plates troubleshooting.

If you have not read the first article to flexo plates troubleshooting, we link it here:
Flexographic Plates Troubleshooting: Problems, causes and solution – Part 1

Curling

  • Problem: Plate starts to curl and potentially causes “plate lifting“ issues
  • Causes: Different shrinkage behaviour of polymer and polyester carrier film on the back of the plate; main exposure too short; plate processing time too long
  • Solutions: All plate making parameters should be reviewed and optimised
© Anyflexo

Insufficient plate hardness

  • Problem: Insufficient plate hardness resulting in reduced print quality, high dot gain and reduced longevity
  • Causes: Long washout time; Short dry time or low drying temperature; low UVA intensity during main- or post exposure
  • Solutions: Confirm correct plate making parameters
Insufficient plate hardness problem in flexo printing plate © Anyflexo

Dirty Plate Surface

  • Problem: Dirty plate surface; Remaining slip sheet layer on plate surface
  • Causes: Polymer residue redepositing onto the plate surface from the processor; dried solvent drops; lint from cleaning towel
  • Solutions: Solvent saturation; condition of washout processor should be checked (especially the last wiping brushes); use lint-free cleaning towels or soft brushes for cleaning the plate surface
Dirty plate surface problem in flexo printing plate © Anyflexo

Insufficient solid ink density

  • Problem: Low solid ink density on the print sample
  • Causes: Condition of the ink; condition and specification of the anilox roller; plate and tape hardness combination
  • Solutions: Confirm and adjust ink viscosity and overall ink condition; confirm condition and specification of anilox roller; consider to use a different plate type and tape; consider to use a surface pattern
© Anyflexo

Pin holing

  • Problem: Pin holing; Ink laydown
  • Causes: Anilox specification; rheology and viscosity of ink; quality of the white printing; preconditioning of the substrate
  • Solutions: Confirm anilox condition and specification; consider to test different plate and tape combinations; consider to use a surface screening
© Anyflexo
Pin Holing
© Anyflexo
Ink Laydown

Dirty printing

  • Problem: Print result is dirty in some colours and with high dot gain
  • Causes: Ink condition not ideal, especially the dry speed should be confirmed, wrong anilox specification; missing dots on the plate
  • Solutions: Confirmation of the condition of the ink; confirm anilox specification
© Anyflexo

Slurring

  • Causes: High impression settings; problems in cylinder rolling conditions; different surface speeds of the cylinders
  • Solutions: Confirm and correct all printing and press parameters
© Anyflexo

Read next Flexographic plates troubleshooting – Problems, Causes and Solutions Part 3