I would only wash a 'quilt-size' piece of warm and natural batting at a time. (I somehow got the idea you were considering washing all ten yards of it at one time. If so, only in a very large laundromat washer and dryer)
I wash it on gentle on a short cycle in hot water - spin as dry as possible - dry it on gentle with a perma-press setting.
Turns out wonderfully well. I've even washed one piece twice - didn't fall apart at all.
(I did wash a couple of battings that I thought would handle washing that totally disintegrated. Ugh! But Warm and Natural does handle washing well. I prefer the flat look.)