Flannel shrinks!!!! When I use flannel, I prewash it a couple of times. It also frays more than regular quilting fabric.
(I've often wondered if the expensive flannel we see in the LQS shrinks, and frays??????)
p.s.---if wouldn't be a bad idea to throw in a Color Catcher to make sure the color doesn't run.
I made a flannel quilt for my grandbaby and he loves the way it feels!