I was at a retreat last weekend, and the instructor taught her method for American Beauty blocks, which are paper pieced. The foundation she uses does not have to be removed, and after washing becomes soft. Since it doesn't have to be removed, you don't have to shorten your stitch, which was great when ripping out mistakes. Her name is Linda Hahn and her website is
www.froghollowdesigns.com. Also, someone mentioned that Ricky Tims sells something called Stable Stuff (50 sheets for $20) and Sharon Schamber has a foundation that she sells by the yard. I went to their websites and they all look comparable.
I am forced to wear a pad each day, so I started saving the wrappings for string piecing. It is a little thicker than dryer sheets, but you don't have to worry about the chemicals and smell left in the dryer sheets.