You could lay the batting out on a bed, lightly spray mist the folds with water, and let air dry. If your dryer is big enough so the batting does not need to be stuffed into it, you can place it in the dryer for 20 minutes (with or without lightly spray misting the folds first). Hobbs wool now has a max shrinkage of 3%, which is similar to cotton batting, so it can be treated in a very similar manner to cotton batting.