8
4. Important Notes and Tips for White Printing
When Performing Overprinting
What is overprinting?
Overprinting refers to printing a white-ink undercoat first,
and then performing CMYK printing on top of the white ink
(or vice versa). The procedure may involve first printing only
white ink, then returning the media to its original position,
and finally performing CMYK printing.
Allow the ink to dry thoroughly.
➢
Dry the ink sufficiently before you perform overprinting
with the next color. Performing overprinting before the
ink has dried enough may make attractive printing im-
possible or cause problems such as reduced weatherabil-
ity.
➢
Drying time differs according to various conditions, but
as a general guide you should use an auxiliary drying unit
(DU-540) and also allow the media to stand for an addi-
tional 15 minutes.
➢
In particular, when you're overprinting a white undercoat
with CMYK inks, allow the undercoat to dry thoroughly
before you overprint it. If the undercoat is not dry enough,
differences in dryness may cause variations in the over-
printed CMYK colors.
Using the middle pinch rollers
➢
The middle pinch rollers may smudge the printed surface
when the media is pulled back. When you perform over-
printing, we recommend securing the media in place us-
ing only two pinch rollers (one on the left and one on the
right).
Preventing misaligned colors
➢
Because the media is pulled back between printing op-
erations, color misalignment occurs between the white
printing and the CMYK printing.
➢
We recommend that you set the [PREFEED] menu item to
"ENABLE". This can help reduce color misalignment to a
minimum.
➢
Use the machine in the recommended operating envi-
ronment. Also, carry out operations in a location having
stable temperature and humidity.
When Using Transparent Media
Loading transparent media
➢
Set the [EDGE DETECTION] menu item to "DISABLE".
Transparent media cannot be loaded unless this setting is
made.
➢
Ensure a margin of at least 75 mm from the leading edge
of the media to the printing- or cutting-start location.
Important notes on the amount of media remaining
➢
When you use transparent media, the presence of media
cannot be detected. In such cases, printing operation does
not stop when the media runs out, and there is a chance
that the platen or the like may become soiled by ink or
that ink may get inside and damage the machine.
➢
If media runs out while printing is in progress, immedi-
ately press
to quit printing.
Using the middle pinch rollers
➢
The middle pinch rollers damage media slightly, and on
transparent media this damage can be very noticeable. If
such damage is a concern, we recommend securing the
media in place using only two pinch rollers (one on the
left and one on the right).
Automatic crop-mark detection
➢
Automatic crop-mark detection may not be possible for
some media, such as transparent media. In such cases,
perform alignment manually.
When Using the Media Take-up System
➢
Performing overprinting requires pulling the media back,
and so the take-up unit cannot be used.
➢
Using the take-up unit may result in insufficient drying
time. It is not suited to printing with white ink.
R1-071122
Copyright © 2007 Roland DG Corporation
