I use a lot of fleece to make double layer mitts and hats and sometimes put it on the backs of quilts. As fleece is not a plant product, I find that it does not shrink or lose colour. If you are worried, go ahead and wash it first. Some fleece stretches a little more than others so you will have to pin it well before trying to quilt it. It is also heavier than cotton so you may not need batting.