I love to use flannel as a backing on my quilts. I have been doing this for years. If it was cheap flannel, I prewash it.Otherwise, I use it unwashed. I quilt it as I would any quilt. Then, I bind and wash. Yes, I know....shrinkage, etc. But it has never been a problem. The quilt always shrinks/shrivels/whatever equally for me, once it's been quilted. And my quilts are frequently gifts with a replacement guarantee. In 20+ years, I've never been informed about a falling-apart or deteriorated quilt so this is my method and I'm sticking with it! 8^))