You might try Retayne to set the color. Actually Stof is a Danish company, with a partnership with Hoffman. Their reputation is for a quality product.
http://www.blogs.fabshopnet.com/blog...ffman-fabrics/ This article makes it sound like Hoffman is responsible for bringing the Stof Quilter's Basics collection to the US, so you might try contacting them if your fabric continues to bleed.