I do not pre-wash fabric but I do use color catchers any time I wash a quilt. (Just in case!) But I know that when I wash a quilt the batting will shrink some and draw the surface fabric in as well. I think the crinkly look is minimized when you allow them to shrink together. When you wash (shrink) fabric first and attach it to unshrunk batting, the fabric will be pulled in but not shrunk.