I have used flannels to make raggedy quilts. If they are not all the same type of flannel I prewash because they don't all shrink the same. I always throw a Shout Color Catcher in when washing them just in case of fading. My friend was making a raggedy baby quilt and she is not a "pre-washer" but you have to with raggedy quilts in the end to get the "look" and when she did the bright pink faded on the white, she was so upset and threw them out immediately. I think she could have rewashed them with a color catcher and saved the project. Before prewashing if you don't have a serger I fold the material wrong sides facing and use saftey pins on each of the corners and a couple in between. That helps keep the material from tangling. I take it out before completly dry then iron it.