Using poly batting and prewashing fabric will make the quilt not shrink. But the "look" of cotton batting after it's shrunk a bit can add charm to certain types of designs. I use the poly batting if I don't want shrinkage and to keep it flat looking-for the more modern types of quilts. I have to say, that when the quilt shrinks up with cotton batting, it tends to hide many boo-boos and not quite in the ditch stitching. So that's a good thing.