I have preshrunk Warm and Natural by machine washing on gentle, and then drying in the dryer. It didn't hurt it at all. However, it seems to thicken a bit as it shrinks, and makes a little bit 'fatter' quilt. I have pretty much decided I prefer the antique look of washing the finished quilt and letting it shrink and crinkle all together. Store bought quilts can't come close to that wonderful look!