Impressions - January/February 2025 - 41

If the print cracks when stretched after the
curing process, the ink is not fully cured.
Photo courtesy of International Coatings
There are many factors that can affect the outcome of a print,
and I'd like to address some of the most common ones, so that
you won't get to the " now what? " point at the end of a print
production. There needs to be checks and balances way before
the final print falls off the dryer to assure that the results are as
perfect as can be. What follows are a number of the more common
sources of trouble when screen printing-problems that, again,
have nothing to do with the quality of the ink a company is using.
Garments: If the garment isn't correct-meaning the size,
color or construction quality-you are the one who applied
the graphic to it. Whether the garment was supplied by you or
the customer, it's your responsibility-and the cost to reprint
the job on the correct garment can be costly.
Image Placement: Whether you printed the left chest image
on the back by mistake or the back image on the front or
whether you accidentally taped off a portion of the logo or
trademark-again, that's your mistake. (By way of example, on
my real first professional print job back in 1981, I printed the
REMO drum head logo on the back instead of the left chest of
72 brown sweatshirts. Not good!)
Ink Type: Did you use white ink made specifically for use
on a cotton garment on your 100-percent poly red shirt or use
a poly ink on a 100-percent cotton garment? Both are no-no's.
Let me explain: If you use a standard cotton white on some dark
polyester fabrics, it's possibly some of the color or dye from the
polyester can migrate or sublimate through your ink and alter
the ink color. Using ink specifically to print on polyester fabric
can help prevent that from happening if used and handled
correctly. Keeping the cure temp as low as the ink will allow
and cooling them off immediately after curing will also help
prevent dye migration.
Similarly, when using ink for polyester on some reactive dyed
cotton fabrics, it is possible, under the right circumstances, to have
the polyester ink bleach or " ghost " an image on any cotton fabric
that it touches. Ghosting only happens when you use certain low
bleed and 100-percent polyester white inks on cotton fabrics
that are still hot and have some moisture remaining within the
fabric. If the printed fabric is left in contact with reactive dyed
fabrics while hot, you may create a ghost image of the polyester
ink print on the reactive dyed fabric.
If you run into such a problem, here's a tip-cooling the
garments off directly out of the dryer will help prevent the
ghosting from happening.
Dryer Settings: Did you make sure that the dryer temperature
is correct for the type of ink being used (low-cure vs. regular
cure type inks) or for the type of garment you are printing on
(100-percent cotton vs. 100-percent polyester for example)?
While heat is vital for curing and fusing ink, finding the sweet
spot is key to avoiding energy waste and maximizing profitability.
Heat is a necessary evil. You need it to do the job, but any excess
turns it into an enemy.
Under-curing is the problem I encounter the most when
people complain about the ink. Use a temperature gun aimed
at the inside of the dryer to measure the temperature more
correctly. Slow down the belt speed if needed. Typically, the ink
should reside in the dryer at least one full minute at the cure
temperature suggested by the manufacturer.
If you do detect that the ink is under-cured, be careful not
to run the ink through the dryer a second time at temperatures
that still would not cure the ink. For example, at 250°F (121°C)
the ink will still be heated to only 250°F (121°C) and still will
not cure if it needs to hit 280°F (138°C) for it to be fully cured,
no matter how long you run it through the dryer.
Ink and Screen Rooms: You can learn a lot about a
screen-printing company just by looking to see how seriously
they take their ink and screen rooms. These areas are key stages
Jan./Feb. 2025
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Impressions - January/February 2025

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