Hobbs batting will be just find to "prewash". I do it often for my customers. I put it into my top loading washer with enough hot water to cover it and let it soak (do not agitate) about 10 minutes. Spin the water out then put it into my dryer on high heat and dry about 20 minutes. It comes out very nice and soft. This will shrank the batting so the finished quilt will not shrank as much it is washed.