I pre-wash everything except pre-cut strips/squares. When I use those, I don't wash any part of the quilt top until it's finished. Then I baste muslin on the back to cover the seam allowances to catch loose threads and wash with color catchers. I'm nearly finished another top that has unwashed Bali Pops 2-1/2" strips in it, so it will get the muslin backing/color catcher/wash in the next few days.