I use sheets from the thrift store. Most of the time I can find 100% cotton but in a pinch poly/cotton will do. They are always available here as we live in a snowbird area. I have never had a problem quilting them with my Tin Lizzie. I do change the machine needle whenever I think of it. If the needle is dull and the sheet is a high thread count I can hear a pop with each stitch that tells me to change out the needle.