Hope the quilt police don't get me but I use new sheets for backgrounds on top, piecing, and backing -- I think most are 100% cotton percale, 180-210 in count -- most are better quality than what I have bought on bolts -- generally the sheets are solid colors and have become part of my working inventory stash -- a few may have polyster in them, but all have worn and washed well -- the problem now is finding less than 300 count and all cotton -- two years ago I bought a king size white set from Ross, 210 count cotton, that had been made for BedBathandBeyond for less than $20 -- it will be the background for my Balt.Alb. quilt -- need to go sheet shopping again