Process on garments is used to reproduce images that have a palette of colors
well beyond the limits of the press. It is effective in reproducing paintings
or photographs and can be used for more graphic images that contain a wide
variety of colors. Some printers also use process to print on colored or
dark shirts but this technique is very labor intensive and the results are
often less than amazing. There are a myriad of technical problems associated
with this process.
Four color process printing on textiles is a technique that has been in a
state of development for over 15 years, even though there are many printers
producing process prints in production on a daily basis. There is still a
great deal of wrangling between knowledgeable printers about everything from
screen angles and frequencies to separations techniques and hardware. It
is due to the fact that there is such a wide latitude in the results achievable
on press with the same set of separations that makes any kind of consensus
quite elusive. The fundamental problem of any halftone reproduction on garments
is the pressure needed to saturate the weave of the fabric, which causes
extreme amounts of dot gain. Shirt printers have employed a vast array of
techniques, most of which are proprietary, to deal with the tonal range
deficiencies. Some printers pay $300-500 to separation houses that specialize
in process separations for t-shirts, while others have spent untold piles
of cash on high end printers.
Not a lot of answers in this section but in terms of industry wide
generalizations this is about the closest we can come. The one conclusion
we can draw is that process separating for screen printed garments is more
problematic than just about any other medium. It is considerably easier for
a marginally experienced desktop publisher to achieve quality results with
the standard desktop separation software, such as Adobe Photoshop, than it
is to create even acceptable results on a shirt. If your images are photographic
and require 4 color process then be prepared to be much more selective in
your choice of printers. Ask to see samples, especially ones that address
reproduction problems similar to the ones in the images you wish to have
printed.