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Possible causes of these problems include:
- Excessive ink emulsification
- Old inks used
- Low temperatures in the press room or low ambient
temperatures where the printed materials were
placed
Excessive ink emulsification is the cause of more than
90% of all such problems. Drying can be improved somewhat
for slow setting printed materials by placing them in
a 25°C to 30°C environment with continual air
movement, but this is not a surefire countermeasure
so be sure to always print in accordance with the YUPO®
printing manual.
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- Use fresh inks designed for YUPO®
- Restrict dampening water to a point just
before the plates become dirty. It is especially
important to minimize dampening water for
the first two colors. If possible, it is
also effective to add alcohol such as IPA
to make the water on the plate as uniform
and minimal as possible.
- These problems tend to occur on sparsely
printed materials, so it is important to
include large solid elements in white areas
on the plate as much as possible and to
keep up the consumption and supply of ink
on the rollers to keep the ink on the rollers
fresh. It is also effective to use a "G
drier" or an "X + Y = DRY drier"
as necessary.
- Ink emulsification problems can occur
if too much ink builds up at the print start
up.
- To improve drying, it is effective to
keep the temperature of the room where YUPO®
materials will be stored after printing
at around 25°C to 30°C.
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