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Originally Posted by tryplecrown |  | | | | | | | | | Do you just allow the shirt to cool to room temperature?
Is there a difference in blends vs. cotton shirts when it comes to this problem? | |  | |  | |
Chlorine is common in blue shirt dyes and blue inks. 50/50 shirts are the bleeders because it is hard to balance the different dyes and different temperatures that 'fix' the dyes to the fabric. Polyester usually ends up with some dye on the surface that makes it hard to stop the dye from contaminating your ink.
This is almost impossible to advise you, and we can't learn anything so we can avoid the pitfall without knowing the ink and shirt specs. More important is - you know that combination doesn't work.
I wrote this in 1986 in my column in Screen Printing magazine, Eddgads. 20 years ago:
Marc S. Willson of (the former) Tucker's Tees Ltd. of Bermuda wrote.
Dear Richard: We've been dealing with a problem of certain manufactures inks which cause a "ghosting" effect, migrating the image from either the inside of the shirt to the back of the same shirt, or the the shirt stacked on top. Ghosting usually occurred after the shirts were stacked for a couple of weeks.
Mr. Willson doesn't tell me which ink brands he is using, so I will answer generally. Ink manufacturers use 'blocking agents' to stop dyes from sublimating and discoloring the ink film. Some low-bleed inks will "ghost" and some won't. This won't help much, but I can't tell you which ones do or don't. You must test, which by the completeness of your letter, I can tell you have.
Bleaches are used to decolorize or remove impurities from the ink in order to achieve whiteness. Remember, whiteness is not opacity. Opacity is a function of ink density, (film thickness and 'light stopping power').
Bleaching is a chemical reaction which uses "chlorines or peroxides" as agents. They do a pretty good job of stopping the problem of sublimation.
When you heat the ink to cure it, the bleaching agents give off gasses. When the gasses are loose and not diluted by the air they do their job and bleach whatever they can. When the polyester shirt fibers are hot, they swell. When they are swollen they soak up the bleach. If the bleach is strong you might get a reaction right away, but when it's weak it may take longer. The bleach will try to do it's job until it's exhausted.
You may remember several years ago there were many problems with light blue shirts that were very susceptible to bleach gasses. It was found that the blue dyes reacted easily with hydrogen chloride gas. Some manufacturers have taken some steps to prevent this with the use of acrylic monomers. They use the acrylic monomer to replace part of the plasticizer.
To cure, the acrylic monomer needs a peroxide as a catalyst. Isn't that handy? The acrylic monomer has two functions. As a plasticizer substitute it resists migration while it ties up the peroxide so it doesn't get out of control.
Shirt manufacturers had to change their dyestuffs and several ink companies had to pull inks off the market because of the liability. I haven't had a problem for quite a while. The only defense is to accept the fact that some inks do this and test to prevent surprises.
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I visited Bermuda a few years later and was overwhelmed with the humidity. I'm sure the moisture in the shirts inhibited the cure of the ink especially at the critical contact point of the ink and shirt. Moisture evaporating from a shirt cools it, just like perspiration cools your skin.
Tucker's had a low energy IR panel oven and that combination doesn't pull moisture out of shirts very well so the cure penetrates completely .
Question about allowing dark shirts to cool? 
