Printed Sheets show color variation from sheet to sheet during the run. Ink film densities are very unstable.
Low ink level in the fountain
Improper roller setting
Ink backing away from the "fountain" roller
Contaminated ink fountain – dust, grit, etc.
Keep ink fountain full to maintain head pressure
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