Is white ink a business necessity, a niche market, or both?
The solution to the opaque/transparent problem is to educate
graphic designers to the nuances of white. Designers must
incorporate white into their designs"?using white as a fifth color.
If transparent colors are required, users must adjust the opacity
percentage in the white channel at the point of creation (in Photoshop,
Illustrator, etc.). If opaque white is necessary, the file
should be adjusted to reflect 100% opacity.
In addition, one of the biggest challenges in creating proper
files is determining if white prints at the same time, or before or
after CMYK. In the DuPont 22UV, for example, the white is printed
and cured in-line for white underneath and white standalone
applications; for reverse-white applications, the colors are
printed, and the white is then overprinted in a separate pass. One
way that Durst has addressed this problem is by giving its Rho
owners the option to specify the order of the printheads, depending
on the majority of their jobs, when purchasing the machine"?
white first for underprints; white last for overprints for backlits.
Will printing white slow down production? Most OEMs report
that the print speeds with white are the same as with CMYK.
However, when a high degree of opacity is required, or a printed
image is overprinted in opaque white, the printer may have to
make a second pass, affecting print speed.
Indeed, NUR's Dror Todress says that the addition of white
can affect speed, depending upon the print mode; "Using the
white ink as part of the image (spot white), there's no compromise
on speed. When covering areas with white (both pre- and
post-printing), there is a compromise on speed."
"The only situation that slows print speeds is when working
with backlit applications as the printer 'double strikes' the image
area and lays down twice as much ink (all inks"?CMYKW) to
raise the opacity. However, this was the case before white, and
not a product of the new white inkset," says Howard of Durst.
Ink/print costs: The jury is out on ink costs"?half the OEMs
queried for this article charge the same for their white ink as
they do for CMYK, while the other half charge more for white, citing
higher production costs.