I am making a rag quilt too. I didn't pre-wash the flannel, but I started putting inside already prewashed flannel. I used scraps of left over washed flannel. Will this create a problem with my rag quilt. I made the squares instead of 6 inch like my patterns, 5. So if the flannel shrinks, I should be okay shouldn't I, I did 18 squares, I really don't want to undo them, but I would rather do that then ruin it all. So, my question is will it work with used flannel. Otherwise, I will cut up flannel and add to it. Thank you.