I know some disagree with it, but I use sheets for backing all the time for quilts I make for family and friends. I have never had a problem quilting them with my machine, Viking Mega. It is so cost effective on my limited budget, 2 or 3 dollars for a sheet vs. what fabric costs. I enjoy searching the thrift stores and garage sales for good sheets to use. Just the other day I saw a quilt for sale online where the top was also pieced with vintage sheets and advertised as so.