You can nail every other part of the screen printing process — perfect exposure, clean registration, smooth ink lay — and still end up with prints that crack, peel, or wash out completely.
The culprit? Under-cured ink.
Dry Is Not Cured
This is the biggest misconception in screen printing. Plastisol ink feels dry to the touch well before it’s actually cured. Just because you can touch it without getting ink on your fingers doesn’t mean it’s going to survive a wash.
Plastisol needs to reach 320°F (160°C) throughout the entire ink film to fully cure. Not just on the surface — all the way through.
How to Check Your Cure
The Stretch Test
Once the print cools, stretch it. If the ink cracks or splits, it’s under-cured. A properly cured plastisol print will stretch with the fabric.
The Wash Test
Print a test shirt and wash it. Hot water, normal detergent, tumble dry. If the print looks the same after 3 washes, you’re good. If it’s cracking or fading, adjust your cure.
Temperature Gun
Point an infrared thermometer at the print right after it comes out of the dryer. You want to see 320°F+ on the ink surface. Keep in mind the actual ink film temperature might be lower than the surface reading.
Temperature Strips (The Gold Standard)
Thermochromic test strips placed under the ink before curing give you the most accurate reading of what the ink film actually reached. These are cheap and eliminate guesswork.
Common Curing Mistakes
Moving too fast through the dryer. Slow down your belt speed. It’s better to over-cure slightly than under-cure.
Printing on thick garments. Hoodies and heavy cotton absorb more heat. The fabric is stealing energy from your ink. Adjust time and temp accordingly.
Flash curing as final cure. Flash units are for gelling ink between colors, not for final cure. They heat unevenly and almost never get the ink to full cure temperature throughout.
Not preheating. In cold shops, garments sitting at 50°F need way more energy to cure. Let your dryer warm up and consider preheating your platens.
The Bottom Line
Test your cure. Every time you change something — new ink, new garment, new dryer settings — test again. A $4 test shirt is a lot cheaper than reprinting a 200-piece order.