There are two things you really are looking for in a plastisol print:

1. Is this print going to last in the wash?

The best way to check this without actually washing the shirt, is the “Stretch Test”. Most cotton t-shirts, hoodies, etc. will have vertically knit fabric. This is not a technical term just a description of what it looks like when you look closely. You’ll notice that you can pull the fabric easily horizontally and see the knit stretch. To perform the stretch test, pick an area on your print and lightly stretch the fabric and print. If the print has been cured properly, the ink will stretch with the fabric and will not crack. If the print cracks or pulls apart as you stretch the fabric, then it has not been cured properly and will wash out.

Of course, you are not going to check every item in the batch, but check a couple of items. It is also a good idea to keep a shirt or two for yourself, wear it, wash it, and put it through the usual wear and tear to see how it holds up. If shirts are washing out, your printer will most definitely re-imburse or re-print the batch for you. If they don’t, then find new printer.