Hi Doc,
I have a few pics for you to show you what an inkjet heat transfer shirt can look like after multiple washes, quite a bit of them involving 1 cup of bleach, just to really toughen up the test.
The key is "which'' paper you use, and the ink. Shirt blank will make a difference in the staying power as well, in my experience.
Here's the link for you to see:
Wow! Jetprosofstretch JPSS & Bleach Results -pictures - Canon Dye ink and Durabrite Pigment ink
While the pics will help you alot, the absolute BEST way for you to decide if this is a process you want to start is to buy a small sample pack of paper (JetPro SofStretch paper aka
JPSS is the best for whites, lights), print them using a printer with Pigment Ink (you will see I also tested Canon regular dye based ink with awesome results, but pigment is the go-to ink for most.), press and test wash them.
I suggest the 50/50 cotton shirts - Jerzees 29 has the best staying power for me, but are a bit thin, eh. Gildan's Ultra Blend and Hanes' Beefy Tees work well with inkjet, too.
Good luck, Doc.