|
PROBLEM |
CAUSE |
SOLUTION |
| TINTING/TONING:
Adhesion of ink
to non-image area of the plate
|
1.Ink
bleeding into fountain solution
2.Improper fountain
solution concentration
3.Ink and dampening
rollers set too tight to plate
4.Ink is taking
on too much water and breaking down
5.Non-image area
of plate has become sensitized and ink receptive.
|
1.Ensure
that the correct level of alcohol(or substitute)is
being used.
2.Check fountain
solution by conductivity to ensure the correct
dosage.
3.Reset to lighter
pressure to avoid "grinding"pigment into
the plate surface
4.Consult with
ink and fountain solution suppliers.
5.Use plate cleaner,if
toning returns remake plate and check fount
strength.
|
| INADEQUATE
SETTING OF INK:
Ink remains tacky
during press delivery and bindery operations,resulting
in set-off,
marking or blocking
|
1.Dryer
temperature too low for speed of web.
2.Excessive ink
film thickness.
3.Poor ventilation
at exit end of dryer,leaving solvent vapours
near web
4.Chill system
not working properly; ink resins are not
setting hard enough
5.Paper is not
porous enough or has too high water content.
6.Ink over-emulsifies
with fountain solution.
7.Ink film is
only set on the surface, and rewets after
the chill rolls from trapped solvent.
8.Ink solvent
is too slow evaporating at this dryer temperature.
|
1.Increase
dryer temperature
2.Run less ink
or use stronger ink
3.Increase velocity
of air-knife scavenger at the dryer exit.
4.Lower chill
roll temperature. Caution:watch for
condensation.
5.Switch paper.
6.Adjust ink/water
balance.
7.Reduce speed
of press. Adjust oven temperature.
8.Consult inkmanufacturer.
|
| HICKIES:
White spots surrounding
a small spot.
|
1.Particles
of dried ink.
2.Paper dust.
3.Dust from overhead
objects(lights,ceiling…)
|
1.Clean
rollers and inkfountain.
2.Consult paper
supplier.
3.Clean all overhead
objects in the work area.
|
| MISTING/SPITTING:
Misting-fine
droplets of ink thrown from ink rollers
Spitting-ink
being thrown from rollers in filaments
|
1.Too
much ink on rollers.
2.Ink too thin.
3.Press speed
too high.
4.Improper ink/water
balance.
5.Inking rollers
are incorectly set or damaged.
6.Roller train
is too hot.
|
1.Reduce
ink film or use stronger ink.
2.Use ink with
more body.Consult inksupplier.
3.Reduce speed
of press.
4.Reduce ink
setting and then water to lower point of
ink/water balance.
5.Reset rollers
and replace damaged rollers.
6.Increase flow
of cooling water.
|
| LOW
LEVEL OF GLOSS: |
1.Paper
too ink absorbent.Paper surface very rough
and grainy.Paper has poor gloss.
2.Dryer temperature
too high.
3.Ink is over
emulsified.
4.Ink film thickness
too low.
5.Ink is too
strong.
6.Excess alcohol.
|
1.Change
paper.
2.Lower oven
temperature and decrease press speed if
necessary.
Obtain "low temperature"
inks.
3.Verify fountain
concentration and set water to minimum level.
4.Increase film
thickness.
5.Reduce ink
with varnish and run higher ink film thickness.
6.Reduce alcohol
to 8%.
|
| PILING:
Build-up of paper
fibres or coating,or ink on rollers,blankets
or plates.
|
PAPER:see
PICKING.
INK:
1.Ink is over-emulsified.
2.Ink is drying
too fast on the blanket.
3.Blanket tack
is too high.
4.Light coverage
uses too little ink.
MECHANICAL:
1.Improper packing
of cylinders or rollers not set correctly.
|
PAPER
: see PICKING
INK :
1.Consult ink
and fountain solution suppliers to reduce
water take-up of ink.
2.Check press
temperature or consult ink supplier.
3.Run more water
or add non-piling additive.
4.Use take-off
strips if possible, to increase ink consumption.
MECHANICAL :
1.Adjust settings.
|
| PICKING:
Pulling fibres
from uncoated or coating from coated papers.
|
1.Too
much water reaching the paper.
2.Poor quality
paper.
3.Impression
cylinder pressure too high.
4.Blanket is
too tacky.
5.Ink too tacky
for paper .
|
1.Reduce
dampener setting.
2.Change to a
better quality paper with better pick resistance.
3.Reduce impression
pressure.
4.Ensure that
blanket is washed completely and not tacky
after wash cycle.
5.Consult ink
supplier.
|
