Friction or rubbing against the pattern. Leaning back into a chair or against a wall. Thats just a thought but I don't think its a concern. If you add the fabric adhesive to the paint I'm thinking they are concrete durable.
I forgot to mention to put a piece of cardboard between the layers of shirts.
Also how the pattern prints is the result. Its a woodcut print so don't expect a perfect solid imprint; its art. My first print I went back and tried to touch up and it looked terrible. Put the ink on thick as you can with a roller or you can sponge it on. Look on u tube for fabric printing videos.
I wash my patterns after every print. I use a brush with diluted Mr. Clean. Make sure your hands do not have paint on them when pressing print because it might transfer.
Photos I have never done. I can tell you that my friends tell me that I should sell them and if they did not look great I would have stopped along time ago.
Today I printed off the jumping bass because it has wide cuts, the peace sign with the word peace and the recycle congress for shirt patterns.
I also found a half moon/half sun pattern on this site that would look awesome on a shirt. Wall accent patterns are great.
You can do a Hawian shirt with patterns repeated all over a shirt. Golf balls,Golf clubs, bluegills, bobbers etc.
Food for thought: printing patterns on a wall