Reference Book
Remedies:-Add driers as suggested by the manufacturer, add gum or binding
agents to control absorption and overprint paper with varnish.
Hickies
It is a condition in which ink spots surrounds a white background. It is caused
by small particles of dried ink, dust or paper dust getting attached to the plate
or blanket.
Remedies:-Clean the press and remove all dried ink from the fountain and
roller, check feeding pile for loose edges.
Piling
A buildup of ink on the ink rollers, plate or blanket. Causes are:- Ink too stiff or tacky
- Emulsified ink
- Improperly ground ink
- Improperly packed blanket
Remedies:-Reduce tack by adding reducing compound, clean-up press and
use proper balance of ink and fountain solution, re-formulate ink and re-pack
blanket.
Printing problems
Blinding
The image area of the plate will not accept ink. Major causes are:- Excess gum in fountain solution
- Fountain solution too acidic
- Excess plate-blanket pressure
- Glazed rollers
- Improper ink tack
- Contamination of plate during plate making
Remedies:- Check the pH of the dampening solution, check the roller pressure
with cylinder packing and blanket packing, deglaze or replace rollers,
reformulate ink to match the stock, clean and rinse plate and re-gum surface.
Ghosting
It is a condition that occurs when solid images print unevenly or a faint second
image appears next to the original. Major causes for ghosting are: - Glazed or hardened ink rollers
- Excess fountain rollers
- Embossed or engraved blankets