I never prewash mine. If I think there may be a problem then I just throw a Shout color catcher in with it. I also cut my middle layer an inch smaller than the other 2 so it won't be hanging out in the ragging. I also will take my rag quilts to the laundromat when I wash them for the first time so that I don't have such a mess in my washer and dryer. Supposedly the dryer at the laundromat will pull a lot more of the lint out. I learned this from a lady at church when I first started doing rag quilts. They are fun. Just made several this summer for my granddaughter that was born in August. Then had to make some doll sized ones since she was born a month early and so tiny.