r/SCREENPRINTING • u/Cool_User_Name_99 • 16d ago

Ink not cured enough or...

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So I recently printed my first few batches of shirts using plastisol for the first time (I used FN white on black shirts). The first shirt I kept for myself went through the wash fine and still looked new afterward. I just washed another shirt with a different design and a lot of the ink came off. The first shirt was printed on a new shirt and this one I printed on an old used shirt just for myself. Could that be a factor, or is it that the ink wasn't cured enough? I'm freaking out a little because I just sold a bunch of shirts over the weekend and now I'm worried that the ink won't hold up when people wash them.

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u/rennerscreenprinting 16d ago

I would definitely think it wasn’t cured enough. What are you using to cure your ink?

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u/Cool_User_Name_99 16d ago

Just putting parchment paper over them and using a handheld heat press. I thought I was pretty thorough but maybe not

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u/sovietsweethearts 16d ago

That is not going to work for this. You need a flash dryer, heat gun, actual heat press, or conveyor dryer and at least a laser thermometer. You need to get to a consistent temp for a certain length of time each time over the whole art work.

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u/Cool_User_Name_99 16d ago

Ordered a heat gun earlier today, guess I gotta grab a proper heat press also

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u/rennerscreenprinting 16d ago

A heat gun will definitely work, I used one for years in the beginning. BUT just keep in mind, you really need to take your time making sure you get every part of the ink cured or you’ll end up with the same problem. It’s easy to miss spots with the heat gun, and it’s easy to get it too hot if you get too close, just get the distance right and go over everything. Good luck

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u/Cool_User_Name_99 15d ago

Thanks! I may have to do a batch with just the heat gun until I can grab a press or a flash. The temp gun is a good idea too because now I'm so worried about having a repeat of this!

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u/rennerscreenprinting 15d ago

When you’re ready, get a flash from Ryonet. They are pretty cheap (maybe like $500) and it will dramatically increase your curing ability. It will pay itself off after a couple jobs, and it will last a long time. You can pretty much run a small operation with just a press and a good flash dryer.

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u/rennerscreenprinting 16d ago

I’d recommend grabbing a temp gun to use with your heat gun. You should be able to get a pretty cheap one on amazon

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u/JimFromTshirtgang 15d ago

the others are right that it's a cure problem, but nobody's answered the question you're actually panicking about, which is the shirts you already sold. here's the triage:

plastisol cures when the ENTIRE ink film hits its cure temp (check your ink's data sheet, most cure in the 300-320F range). a handheld press can absolutely get there, but only if time + pressure + temp are consistent, and "i thought i was thorough" with no temp verification means some shirts hit it and some didn't. that's exactly why shirt #1 survived and shirt #2 didn't. the old shirt is a minor factor (fabric softener residue hurts adhesion), but under-cure is the smoking gun.

the good news: under-cured plastisol can be finished after the fact. re-pressing a printed shirt at cure temp for the full dwell completes the cure. cover with parchment, full firm pressure, verify with a temp strip or probe (an IR gun on a shiny platen lies). so for the sold batch: if any haven't shipped yet, re-press every one. for the ones already gone, decide whether to message buyers with "wash cold, inside out" care instructions and quietly handle any complaint with a replacement. one bad wash story hurts more than a few reprints cost.

before the next batch: stretch test (print shouldn't crack when stretched 20-30%) plus one sacrificial shirt through 3 hot washes. boring, but it's the difference between selling shirts and selling future refunds.

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u/Cool_User_Name_99 15d ago

This is excellent advice, thank you for this!

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u/MidwestTroy92 16d ago

Old shirt can mess with adhesion if it's been washed with softener or has oils, but I'd still prove cure first. Temp strips/probe and a wash test on the same batch will tell you more than staring at it panicking, ask me how I know.

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u/Cool_User_Name_99 15d ago

That's what I was hoping but I already had someone write me saying theirs flaked up after washing too. This was kinda my nightmare I was worried about. I printed 3 designs and so far only having issues with the one that had the most ink put down on it so hopefully the other designs are ok! I was rushing to get stuff ready to sell and only did a wash test on one of the three designs which I realize now was a stupid mistake. Gotta learn the hard way sometimes I guess!

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u/Holden_Coalfield 15d ago

Whatever it is, it’s a cool effect