I preshrink my Warm and Natural batting in hot water and no detergent. I let it soak in the water until it is completely wet. Keep pushing it down into the water with a ruller because it will float. Do not agitate it but do sping the water out. Then I put it in the dryer. If it going to shrink, I want it to shrink before I hand quilt it. I think it softens the batting and its easier to stitch.