I have used batting in my rag quilts, low loft, cut the finished size of block. If some gets caught as I'm sewing together, then I trim it out when I have to go back and rag all blocks. I've also used flannel. I like both ways. However my blocks have alittle more puff after quilt is washed. I like the effect of rag and puff, But it's your quilt and your choice, However you choose it will be beautiful.