Lori - I would definately pre wash the flannel! It tends to shrink more than regular cottons. I broke my own rule and didn't wash the 100% cotton I used on the front but I did wash both of my flannels. I didn't have any problems when I washed the final project and I wash in warm water.

I think my next rag quilt will have 100% cotton on the front and back with flannel as the batting and I will pre wash all my fabrics this time but especially the flannel.

Thank you for your quick reply.
I'm a novice sewist and have had difficulty in determining fabric characteristics. I was hesitant to make a rag quilt out of cotton because I like the 'raggy-ness' from flannel, but I found the perfect material in cotton, so I hope it frays and is soft enough to give me the effect I'm hoping for. I'm also thinking a better quality of flannel would be the way to go.

I am bless I got a Go! Studio for Christmas. I have Rag Quilt Kit out of Denim, Cotton or flannel. PM me with questions. I love the Rag Quilts. So many different fabric you can use and they are great outdoors.

This discussion is just what I needed! My co-workers and I are making a flannel rag quilt for a friend undergoing chemo. I bought several yards of Kaufman Cozy Flannel and just prewashed them. Width before washing was 43" and after washing was 40". I didn't measure length before washing, but each cut still measured 1 yard at least. (Fabric.com might have been generous?) One thing for sure, it is lusciously soft and cozy! We are not using batting and just two layers of flannel. After all, this is South Texas!