I always test any colored fabric I purchase, even before I prewash! I don't use hand-dyed fabric in my quilts -- because it's too expensive for my budget. If I am unfortunate enough to have purchased a fabric that bleeds, I treat the bleeding fabric with a "dye setter" product I discovered, re-test to make sure the treatment has worked, and use the fabric, knowing I've done everything I can to prevent a "bleeding" quilt. I've never had a fabric bleed after treating it.