We have discussed this at our guild. One of the girls has taken classes at a local museum and they use Orvis soap. It is bought at the harness shop and is basically used for kids who are entering their horses in the country fairs because it cleans good and makes the horse shine. I bought some to use on a quilt I made for my GD. She (or someone) had spilled someone on it and it mildewed and I soaked it with dawn and it did not touch it. So I will try this, just waiting for a nice day because I want to hang it out on the line to partially dry. Good luck on your quilt.