Screen Printing - April/May 2020 - 18
ments, fillers, and various chemical additives. Plastisols and
acrysols contain plasticizers that cross-link with the plastic
resin. These plasticizers don't evaporate off, but become part
of the ink film. Water-based inks, on the other hand, rely
on solvents that evaporate, leaving the pigmented binder
compounds on the garments. These evaporative solvents
may represent more than 70-percent of the ink. While the
primary solvent is water, water-based inks often contain cosolvents such as alcohols, glycols, and formaldehyde. These
co-solvents may be harmful and put printers at risk unless
they are properly protected from the evaporative fumes.
Printed with Ultramix Axeon Non-PVC 1200 Series PMS Color Mixing
System and Axeon Non-PVC Crystalina Shimmer 1855. Reprinted by
International Coatings with permission f rom artist David Edward Byrd.
in the screen because they don't cure until they're heated.
Plastisols are considered "100-percent solids" and consequently provide virtually a 100-percent yield. What you print
on the garment stays on the garment. Most water-based inks
contain 20 to 30 percent solids. The highest solid, waterbased inks contain no more than 70 percent solids.
Printers looking for an alternative to PVC are generally looking to acrysol or water-based inks. Like plastisols,
acrysols are made up of 100-percent solids and provide the
same high yield. They're easy to use, and print and behave
like PVC plastisols. They don't dry in the screen and most
don't require a flash after every print.
There's a misguided notion that water-based inks consist
of water and pigments. That is incorrect. All water-based
inks contain a plastic binder (usually an acrylic or urethane)
and various additives (pigments, fillers, retarders) that are
suspended in water and other co-solvents. In fact, many
high-solids, water-based inks contain relatively little water.
Water-based inks aren't as popular as plastisols in North
America, largely because they're not as easy to use (drying
in the screen), not as efficient (lower yields, daily cleaning,
more waste), require more energy and time to cure, and in
the case of some "high-solids" inks, are more expensive.
Claims that water-based inks are more environmentally
friendly than plastisols and acrysols are questionable at
best. All three inks rely on plastic resins or binders, pig18
SCREENPRINTING | APRIL + MAY 2020
Plastisols, acrysols, and water-based inks have environmental footprints that are quite different. Water-based printing
generally requires more energy to power more flashes and
cure/ventilate (to drive off the moisture) and more water
(primarily for daily cleaning). At the end of a print day, plastisol and acrysol can be left on the screen or put back in the
bucket for use at another time. This is not necessarily so with
water-based inks. Water-based printing consumes more water and generates more water waste. That waste, quite often,
is accidentally poured down the drain.
The common misconception is that water-based inks
are benign because they're largely water. Not so. They're
chemical compounds that, aside from their harmful cosolvents, contain other chemicals (binders, fillers, additives,
mold inhibitors, and pigments). Some of these chemicals
are considered hazardous and must be managed as such.
Plastisol and acrysol waste that can't be reused can often be
recycled for other uses or, when cured, can be disposed as a
regular plastic. Water-based binders in some cases may be
disposed similarly if all solvents have evaporated.
The point here: take the time to learn which inks work best
for your situation. I'm not suggesting plastisols and acrysols
are better than water-based inks. But at the same time, waterbased inks aren't necessarily better or greener than plastisol or
acrysol inks. Remember that, in the end, how you manage your
shop - materials, energy, workflow, reuse/recycle, and waste -
will largely determine how "green" your operation is.
The next time you hear a claim about one product being
green or greener than the next, take the time to understand
the basis of that assertion. Someone may be attempting to
"greenwash" their products.
Steve Kahane is International Coatings' president and CEO. Prior to joining
International Coatings, he held senior executive positions in the environment and engineering fields, and served on the faculty of the UCLA School
of Public Health where he taught a core course on environmental health.
Screen Printing - April/May 2020
Table of Contents for the Digital Edition of Screen Printing - April/May 2020
Screen Printing - April/May 2020 - Intro
Screen Printing - April/May 2020 - Cover1
Screen Printing - April/May 2020 - Cover2
Screen Printing - April/May 2020 - 1
Screen Printing - April/May 2020 - Contents
Screen Printing - April/May 2020 - 3
Screen Printing - April/May 2020 - 4
Screen Printing - April/May 2020 - 5
Screen Printing - April/May 2020 - 6
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Screen Printing - April/May 2020 - Cover3
Screen Printing - April/May 2020 - Cover4