I thought that the only difference between backing and "cotton" is the width most backing being 108" not 40". Sometimes backing does feel difference but you should be able to use it in the front of the quilt. 108" backing is much easier to work with than piecing 40" fabric together. I try to use wide backing unless I cannot find a good color. Sometimes I will make my own backing from left over fabric but this is really a pain. What I do is start with a square in the middle and keep adding wide border until I get the size I need.