The most common question and concern we get from our customers is “how do I know this wont come off in the wash?”, or “Please use the good ink, the last printer didn’t and the ink came off in the wash”. Little do they know, this has nothing to do with using good inks, bad ink or different brand inks. What they don’t know is the issue of ink peeling is off is directly related to how the garment is cured.
Curing inks is the process at which the plastisol ink, made of of PVC and plasticizer, is chemically bonded to the natural garment fibers. This process is also sometimes called fusion. The way to to cure inks is generally the same on almost all types of plastisol inks, heat the ink up (on all layers) to about 325-350 degrees Fahrenheit using a conveyor dryer. At this temperature a chemical reaction occurs which fuses, or bonds the ink into the fibers of the garments and permanently secures the ink onto the garments. Once this chemical reaction takes place and the ink is considered “cured” it would be nearly impossible for the ink to comes off in the wash, peel off or scratched off the shirt.
There are two major tests which most screen printers use in order to determine if plastisol ink is cured. The first and most common method used is what screen printers call the “stretch test”. The stretch test consists of the print-master running the shirt through the conveyor dryer and let them cool off for a bit. Once the shirt is cooled off the print-master stretches the fabric just enough so that the ink can stretch as well. If the ink cracks more than 20% it means that the ink is not cured and most defiantly will come off in the washing machine.
The second and least common test would be to run the shirt through a few washing machine cycles. Ink that is not cured will come off within the first 1-2 cycles, but if the ink stays on the shirt and does not crack – you are good to go.
When a customer orders his/her batch of customized garments, they always want to be assured that their money is not going to waste. Many times they ask about the ink coming off in the wash and it is smart to educate them and inform them of how you dry your shirts. Also it would be a good idea to show them samples of previous items printed which were put through multiple wash cycles and stretch tested. This will give them the reassurance needed to trust you as their local screen printing company.