Impressions - October 2014 - 42

Heat-press marks strike through to the garment due to pressure on
the racer back seam when loading ﬂat onto the press.

New dyeinhibiting
digital transfers
stretch and apply at
a low temperature,
making them ideal
for heat printing on
performancewear.

Impressions | October/November 2014

synthetic materials. Whether polyester
or nylon based, these products usually
are sensitive to heat. When heat-pressing
these fabrics, the dreaded heat press marks
can be left behind on the garment, scorching or even melting it. For this reason, look
for products in every heat-transfer category that limit the fabric's exposure to heat.
It's best to ﬁnd products that apply at a
low temperature for a short time at
the lightest pressure.
Before ordering, printing
or cutting transfers, place
your intended fabric on
the heat press and run a
dummy application for
the exact time, temperature and pressure you
intend to use. It's recommended to test an
inconspicuous area so
the garment can be
reused if scorched.
Though similar to
heat sensitivity in that it
should be tested, there is more
than meets the eye when it comes
to pressure sensitivity. This variable
mostly involves how you load the
garment on the heat press. Most of
today's decorators have invested in
"threadable" heat presses with interchangeable lower platens. This type is
essential when printing performancewear. The key to the perfect pressure
is ensuring the print area is completely
ﬂat. With synthetic fabrics, any raised

area - such as a seam on the press area
- will cause an issue. The seam receives a
lot of the applied pressure and, therefore,
scorches easily, which can ruin a garment
or compromise quality. Seams on the
backside of garments that are not threaded
onto the press also can print through easily, ruining an item.
The last pressure challenge is gaining an
understanding of how applied pressure is
dispersed across various surface sizes. When
switching from a 16" x 20" lower platen to
a smaller platen (such as 6" x 10"), pressure
needs to be reduced. Decorators often apply too much pressure to small areas. For
this reason, we hear a lot of complaints
about heat press marks on performance
polo shirts with left-chest graphics.
Dye migration is another factor to consider. Polyester garment manufacturing
leaves a dye in the fabric that can become
unstable when heated. If applying a lightcolored graphic to a darker-colored polyester fabric, then dye migration or bleeding
becomes an issue. While low-temperature
materials will help to inhibit the possibility
of bleeding, it is best to test your fabric
for dye-migration issues or select a dyeinhibiting material. Heat-transfer manufacturers have bleed-resistant materials
that apply at low temperatures to address
migration. Also, garment manufacturers
are increasing their investments in stopping this issue by offering cationic polyester fabrics that are a lot less likely to bleed.
When heat printing performancewear,
sometimes the garment will leave an
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Impressions - October 2014

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