I've never been able to get dried urethane off of clothes,
I usually just retire them after awhile. I've got lots of old shirts that are ruined, and
I just got urethane on a good pair of pants, which I'll end up having to retire sooner than later too...
with cloth interiors, I would recommend not getting it on there in the first place, and if it does happen, try using
Essex u421 by dabbing the spot with a clean rag each time.
I've found that after you get urethane on your clothes, Don't touch it, wait about 20 min., and it will peel off. If you try to clean it, or smear it, this won't work.
This is only a thought. Urethane does not stick to rubber, so why people stick windows in with butyl and
back seal with urethane is beyond me, but, with that in mind. Try spraying some
ScotchGuard on your clothes and letting them air out outside and then when urethane does get on your clothes, after it cures, it should peel right off.
I don't know if it works or not, but it sounds like a good idea to me, kind of like
Teflon for your clothes. ScotchGuard can be gotten at any hardware store. Follow the instructions and always use outside. It can be lethal if used indoors. Wear a basic paper mask, because if this stuff completely coats your lungs (has happened to people who shoot this stuff indoors), it's a trip to the ER for a washing of your lungs. Use it smart and it's a great product.