Screen Printing - August/September 2017 - 31
FIGURE 3 Detail of a print done with an
HD base and foil applied very carefully
FIGURE 4 Printing HD inks with a wallpaper
brush instead of a squeegee can produce
unusual textured effects. It's more effective
when the bristles on the brush are cut down, as
in this photo. Such effects are usually printed
manually, but you can also clamp the brush
into the squeegee holder on an automatic.
In all types of HD printing, use soft squeegees with minimal
pressure. I like to use a 55/90/55 triple durometer squeegee
whether printing on an automatic or manual press. Use a deep
squeegee angle and just enough pressure to clear the screen.
One stroke is best, as a second one can cause the ink to spread
under the screen and smear, ruining the effect. You can get a
wonderful textured look in your print by using a wallpaper
brush instead of a squeegee and cutting the bristles down (see
Figure 4). This is easiest when printing by hand, of course, but
you can also trim the handle in addition to the bristles and then
clamp the brush into the squeegee holder to print on an automatic. Figure 5 shows a close-up shot of a print with a silver
gel onto an HD black ink that was done using this technique.
Some HD inks are very thick when printed, but surprisingly, they flash fairly quickly, not unlike standard plastisol
inks. I prefer using an IR flash unit when printing manually
and a quartz unit on an automatic. The temperature needed to
fully cure HD inks ranges from 325-380 degrees F through the
entire ink layer. Because of the thickness of the ink deposit,
in addition to raising the temperature, you'll need to slow
down the conveyor of your curing unit as well to get enough
heat through the print to fuse the ink.
Remember what I mentioned earlier about the different
finishes of HD inks and gels after curing. Inks should have a
matte finish with sharp edges. If they are glossy after curing,
chances are the temperature was too high. Gels, on the other
hand, should have a glossy finish with rounded edges when
they are fully cured. If they are undercured, they will look
FIGURE 5 In this print, silver gel was printed
on top of an HD ink using a wallpaper brush
to create the textured effect.
just like an HD ink, with a matte finish and sharp edges.
HD special effects require a lot of heat, so white shirts
may not be the best choice for this work as they could easily
scorch. Dark-colored shirts are definitely more forgiving. Performance fabrics and other heat-sensitive materials are also
not the best fit for HD effects. When printing a lot of complex
layers, use a hand-held heat gun to carefully gel the inks as a
flash may get too hot in one area and cause a problem.
Most of the shirts for this article were done by European
T-Shirt Factory, Istanbul, Turkey, a very capable, high-volume
producer of printed apparel. (The shirts illustrating effects
with gel inks and foil were done during a workshop.) These
shirts were created for technical printing competitions and
were designed to test the limits of HD technology, not to
produce wearable garments. But the company does a lot of
production work with HD effects as well, and these awardwinning shirts suggest what this technology is capable of
with a little creativity. With experience, I'm sure you'll grow
to love HD inks for special-effects work as much as I do.
Charlie Taublieb is the president of Taublieb Consulting, Greenwood
Village, Colorado. A member of the Academy of Screen & Digital Printing Technology, Taublieb has 40 years of experience as an educator and
consultant in the industry. He conducts educational workshops around
the world and is a frequent author and speaker at industry events. He
can be reached at email@example.com and www.taubliebconsulting.com.
This article first appears in the June/July 2014 issue of Screen Printing.