This topic made me laugh. I remember I once marked a baby quilt (made from nylon tricot). I picked it up about 2 weeks later to put it on the frame for quilting and it disappeared. I mean the markings literally disappeared. Duh! I had used a disappearing ink pen to mark it with. Well....it just happened to be very humid and damp those two weeks. Yep!!! it had disappeared alright. Had to remark the who quilt again.