I appreciate the advice given here but I have a washing machine with an agitator that I can't disable. It rudely shredded a full-size batting.
On my attempt to manually soak, I was struggling with how to manage such a large piece of wet batting.
It occurred to me to put the batting inside a plastic laundry basket. Then I set this inside the tub and filled the tub with warm water.
This made it easier to soak, then squeeze water out.
I used kitchen gloves so I could use hot water.
Then I had a nice carrying basket for hauling iqit to the dryer. It took 90 minutes to dry!
