I have never used sheets for backing. I am sure my friend takes out the hem. I know she prefers the sheets. I have a friend who does my quilt tops on a long arm machine. She always puts the backing on for me.She uses a white muslin. If I tie a quilt I use muslin for the back, for my baby quilts, I use a contrasting color for the back. You can lay your quilt top on top of the sheet and see how much you can trim away.