Answer by
tamkees (3203)
Acrylic paints are water-based, which means when you wash your clothing, the dried acrylic will "reactivate" in a sense and chip, crack, peel, and possibly stain other clothes. Adding textile medium changes the composition of the acrylics so that none of those things happen. I've had very good luck with it and wouldn't attempt using acrylics on fabric without it.