Impressions - April 2020 - 37

ANOTHER INK CONSIDERATION
Can your ink be printed through high mesh counts? This may be
an important factor if your shop offers halftone, photorealistic or
detailed prints. Be sure to check for this characteristic in your ink.

white underbase for printing on dark substrates. For water-based
inks, many screen printers prefer to use a discharge ink, which
basically bleaches the cotton shirt during the curing process,
creating the equivalent of a "white" underbase. Subsequent
top colors will appear more vibrant.
Discharge inks often contain toxic chemicals, sometimes
even the carcinogen formaldehyde. Beware that chemicals in
the ink may be released into the air and may be toxic to the
operator. The environmental and human impact associated
with using discharge inks and the additional energy-output
requirements for pre-heating pallets or extra flash units should
be considered in your analysis.
When printing on polyester substrates, consider the fabric
content and how it was dyed. Most medium-to-dark garments
can bleed or sublimate residual dye during the curing process
due to the heat needed to cure water-based, plastisol and acrysol inks. To contain the bleeding dye, you may need to print a
gray or black dye-blocking ink to help absorb the excess dye.
This means other inks must be added to the printing process;
thus, extra heat and dryer duration will be needed to achieve
a proper cure.
You also can print on polyester or polyethylene/non-woven
fabrics using low-cure inks. Does your ink line accommodate low-temperature curing - typically around 275°F? Not
all shirts are 100% cotton, and many of today's trendy ecofriendly or recycled-material shirts are synthetic blends, requiring bleed-blocking ink technology or low-cure capability.
Ink Coats
Since the acrylic resins in acrysols cost about three to four times
more per pound than regular plastisol (PVC) resins, finished
inks end up costing about double per pound.The resin makes
up about only 35% of the total ink.
However, the new acrysols still contain almost no solvents;
they are considered to be 100% solid. What you apply on to
the shirt remains there, so you get what you pay for. Nothing
evaporates or is wasted.
When using high-solids, water-based inks, expect about 35%45% of the product to be solvents or other liquids that will be
released during the curing process. If using regular water-based
inks, the solvent content usually is 60%-70%, so keep that in
mind when comparing finished-ink costs and yields.
Flashing
With regular plastisol inks, the need to flash colors can be avoided,
when possible. Normally, you only need to flash white underbases or during the process of printing a few colors (an average
of one to three flashes for an 11-color design on a dark substrate,
for example).
Plastisol inks are fused with heat, typically around 320°F, and
can gel at even lower temperatures. Heat is your friend when you

This design was printed using non-PVC acrysol
inks with fluorescent and glow-in-the-dark
properties. Photo provided by International
Coatings; artwork reprinted by permission from
David Edward Byrd.

Discharge inks
often contain toxic
chemicals, sometimes
even the carcinogen
formaldehyde. Beware
that chemicals in the ink
may be released into
the air and may be
toxic to the operator.
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Impressions - April 2020

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