Just a little side information here. After quilting a full size that had been marked with frixion pens I washed it in cold water. The marks did not come out. The water temp reacted just as a freezer would I suppose. When I put it in the dryer they were gone. Next one I will try warm water just to see what happens. Whatever the case I'm very happy with them and have never had a bad result. I iron the marks away when I use them for embroidery patterns.