If you wash the majority (or in my case ALL) of your fabric before you piece it, then you will also want to wash your backing fabric. If you are a quilter who doesn't wash her fabrics before making a quilt top, then it isn't as important to wash it. The main reason is shrinkage. You don't want your top and back to shrink differently because that could pull your stitches loose or cause other problems. I wash everything because I want any shrinkage to already have taken place, plus I want any excess dyes and chemicals removed from the fabric before I start working with it. Just my personal preference. :wink: