Funny thing, I always wash all my cotton fabrics first, but I have never thought to wash the Minky. It doesn't bleed or shrink to my knowledge. I have made half a dozen quilts with Minky backing and have had an issue with only one - a dimpled fabric from JoAnn Fabrics. I always use Elmer's School Glue to baste the sandwich, but that particular backing wouldn't stick to the Elmer's. I had to spray baste it. Now I always use only Shannon Fabrics Cuddle.