Amma the crayon melts into the paper (use new sheet with every heat set) just make sure you don't have any crayon flakes from the coloring where you don't want them because when you iron to heat set the crayon you will melt the flake into the fabric and it stays for good. I've colored T-shirts with the grandkids and they wash and dry fine. I've notice that the first washing may fade the color but additional washing there is no change. By the way I just use regular crayons not the fabric ones.