You can soak it in the washing machine until it is saturated and then spin out the water, but do NOT allow the machine to agitate the batting! Machine agitation is really hard on a batting. While Warm and Natural might survive it, a lot of battings will not. The only agitation you would do is to press down with your hands. So add water, stop the machine, allow to soak, then advance the control knob to spin cycle. It's okay to dry in the dryer after excess water has been spun out.
Edit: Oh, and you mentioned 10 yards of batting. I would cut it down to quilt-size pieces and do them individually. I wouldn't try to do 10 yards at one time!
Oh, and I should add that Warm and Natural is needlepunched through scrim. That makes it very sturdy and is one reason why it won't fall apart if you pre-wash it. Some battings cannot be submerged in water at all because they will fall apart.
Last edited by Prism99; 10-17-2012 at 01:40 PM.