If you don't preshrink every thing when you make clothing it may end up too small the first time you wash it. To preshrink batting, put it in the washer and fill with hot water. Turn the washer off!! Do NOT let it agitate!! Let it soak for 10 minutes or so and turn the washer to spin. Dry in the dryer. You'll need to take it out and rearrange it a couple of times. It'll roll itself into a ball and the outside will be dry and the center won't so you need to rearrange it.