I made a queen size flannel quilt years ago. The fabrics were of varying degrees of quality. I washed each one in very hot water and totally dried them. The shrinkage on some of them was incredible. When I took my quilt to be washed and dried at a local dry cleaners, the owner tried to talk me out of it because he had some bad experiences with flannel quilts. I insisted it be cleaned. Afterwards, he told me my quilt was the first time he cleaned a flannel quilt that resulted in no distortions. I credit it to washing and drying prior to cutting. So, bottom line, wash in hot water and totally dry flannel.