I usually use Hobbs 80/20 and throe in dryer on fluff for a while.
Here's a question that has me stumped: If I want to preshrink the batting, how would you do it when you have a front-loading HE machine? It uses a scant few inches of water so can't soak the batt there. I wound not be able to manage it in the bathtub... too heavy to try to lift and squeeze the water out.