I use warm and natural batting. When I remember it, I wet the batting in warm water (you have to do some squishing to get it to take in the water (maybe partially unfold and put in bath tub; however, I only have a shower, so do it in the kitchen sink) and squeeze out the excess (don't twist it), then put it in the dryer. I've never had a problem with it, as I don't care for the crinkled look.
bkay
Added: You might wet your top and dry it to preshrink as well. I would dry it in a lingerie bag to keep it from too much motion. Then, you'll have to iron it. I haven't tried it, but will in the future.
Last edited by bkay; 11-17-2019 at 08:43 AM.
Reason: additional thought