i prewashed warm and white on my last quilt i made because even tho warm and white only shrinks 3% i didnt want it to shrink at all the key to washing it so it doesnt fall apart is DO NOT let it agitate in the washer, i just filled machine with warm water let it soak for a while then skipped the agitate let it rinse and spin , put it in the dryer and dried it then used it in what i was making