The main reason I can think of to use flannel is that it is absorbant, holds heat well, and is natural material. I see no reason why a diaper wouldn't work every bit as well. In some ways it would be even easier, especially the already made kind-no folding. I am new to this therapy, but I say try the diaper. I'm all for doing things easily and inexpensively. Hope this wil help more than the sarcasm did.