Impressions - April 2024 - 23

Finished design.
This series of images from International Coatings' in-house design Thai Warrior (above) depicts
the vibrant results you can achieve with the right tools. Capillary film was used for the HD
Clear 141 mixed with Metallic Silver 96 ink (at left). A closer view of the High Density/
Metallic Silver ink used (top left). Images courtesy of International Coatings
typically need even more time than. that. I assure you that the ink
manufacturers thoroughly test every batch of ink before they package
each lot of products.
Often the dryer is being pushed to consume more shirts to increase
productivity. I'm referring to " pushed, " because you may have three
machines feeding one dryer and in order not to slow down the money
machines, the speed of the dryer belt is increased to accommodate
the number of garments being printed. This is understandable but let
me warn you: time in the dryer is your friend and heat is a necessary
evil. You need the minimum temperature to cure but no more. If you
push the dryer by placing more garments at a faster speed, the ink
may not correctly cure.
Let me give another scenario: black ink on a plain white garment
cured great, but today the layers of ink on the red garment seem to
crack. Same dryer settings for both, what could be wrong?
Were any additives included in the ink, for example, reducers, pure
pigments or a catalyst, that could be affecting curability? Or you may
have a standard cotton white T-shirt with a simple black print that
doesn't require a long dwell time in the dryer. Are you combining it
with other types of prints in the same dryer? A red polyester blend
garment, perhaps, that is more sensitive to heat? One with a thicker
ink deposit, so you need a longer dwell to cure the stack of thick inks
(Blocker/white/color)?
It can be very difficult curing different types of print and/or substrates
at the same time or belt speed. If you increase the dwell time
to accommodate the poly blend garment, the white shirt could get
scorched. Inversely, if you lower the cure temperature to prevent the
red fabric from bleeding, the ink on the white shirt may not cure completely.
There simply isn't a " set it and forget it " setting.
Remember, time is your friend, and heat will become your enemy
if not properly managed.
If the belt speed seems to be correct, use a donut probe to see if
there are any cold spots in the dryer. The probe can show if the dryer's
internal temperature correctly matches where its temperature is set.
Many large shops producing tens of thousands of prints per day
have a designated person who roams from dyer to dryer throughout
the shift. Their job is to document the dyers' temperatures and create
individual profiles of each. Then they adjust the individual dryer settings
when necessary to avoid any potential disasters.
Every dryer has a personality, and over time you can anticipate any
variables that may come up. For example, if it's raining or windy outside,
or if a garment is being printed that has a high poly content, or
a print with a thicker ink film deposit, all these factors and countless
more, can affect the cure.
In the end, washing your garment a few times will give you peace
of mind or can keep you up at night. Cured ink will stay on the garment
during the wash, whereas uncured ink will come off. The good
thing about plastisol is you can always re-run it through the dryer to
correct an under-cure situation. Other types of inks may not give that
option, so as they always say, doing it right the first time is always
the best option. 
Kieth Stevens is the Western regional sales manager for International Coatings.
He has been screen printing for more than 42 years and teaching screen printing
for more than 12 years. He is a regular contributor to International Coatings' blogs;
and won SGIA's 2014 Golden Image Award. He can be reached at kstevens@
iccink.com. For more information, visit iccink.com. You can also follow the
company's blog at internationalcoatingsblog.com.
April 2024
P.23

http://www.iccink.com http://www.internationalcoatingsblog.com

Impressions - April 2024

Table of Contents for the Digital Edition of Impressions - April 2024