Troubleshooting Guide

Problem: Printed Sheets show color variation from sheet to
sheet during the run. Ink film densities are very unstable.
Causes: Low ink level in the fountain
Improper roller setting
Ink Emulsification
Ink backing away from the “fountain” roller
Roller Stripping
Contaminated ink fountain – dust, grit, etc.
Solutions: Keep ink fountain full to maintain head pressure
Reset rollers
Decrease water or add heavy body varnish
Agitate ink in the fountain or increase ink flow
Deglaze the rollers
Remove ink, clean fountain, replace with fresh ink

Ink Drying on the Rollers

Problem: Ink is drying on the press rollers
Causes: Excessive Drier in the Ink
Light – Take off of ink
Roller Pressure is too great, thus creating too much heat
Fast drying varnishes in the ink
Solutions: Add Anti-oxidant to retard the drying
Reduce ink strength to carry more ink
Adjust rollers to minimum pressure necessary to properly transfer ink
Add Alkyd varnish to the ink (increases flow –holdout)

Print Mottling

Problem: Print Density is Uneven
Causes: Too much impression
Too much ink being carried
Low viscosity ink may look mottled on papers with uneven holdout
On some stocks, transparent inks will show more mottle
Solutions: Check Blanket Impression and plate to blanket pressure
Run a stronger ink to permit a thinner film
Higher viscosity ink will have less absorption and reduce mottle
Use a more Opaque ink

Excessive Plate Wear

Problem: Image areas of the plate begin to disappear
Causes: Ink too strong for long runs
Fountain Solution is too Acidic
Plate to Blanket packing is too high
Ink may have a poor grind
Plate exposure may be too short or too long
Abrasive paper particles
Ink emulsification and poor transfer mistaken for plate wear
The form roller is too tight against the plate
Solutions: Reduce ink strength and carry more ink
Increase fountain solution pH
Check plate and blanket packing
Check Ink Grind
Change to a new and properly developed plate
Change paper if possible
See remedy for ink emulsification
Check form roller setting

Ink Trapping

Problem: Poor Trap or Overlay between the colors during process printing
(wet trapping)
Causes: Not enough tack difference between colors
Second down color is stronger than the first down color
Too much water and ink combination
Improper ink film thickness on the rollers
Paper has too much holdout
Solutions: Increase the tack and viscosity of the first down color
Strengthen the first down color or weaken the second down color
Reduce the amount of water and/or ink
Try a more quick-setting ink