I've seen them before.You can get them at an office supply store. I tested it on a scrap of fabric, yes the line when away when you ironed it,but I stuck it in the freezer and the mark came back. I know.....who sticks a quilt in the freezer, but what I'm trying to point out is that the chemical is still in the fabric. What will happen to those markings 10 years from now? I'd use it with caution.