I am glad to hear many of you save $$$ 's by using bed sheets for backing. Oh my goodness, they are so quick and easy to load on a frame, and there is no piecing. I buy only flat sheets, but fiber content is not a matter of concern. I use a quilting machine and love the feel of the well-washed sheets. Mine all come from the Thrift stores. Getting them for a couple of dollars makes the quilt cheaper to produce. My quilts are given to charities so I make them the most economical way possible.
Quilters are practical!!