I use these pens for marking to hand quilt the pen's write in a purple marker and will disappear after a few hours. I don't have to worry about marks that won't come out. I just mark what I can do in about an hour or so. They fade really fast one you have quilted over them but I have had them stay visible for 5 or 6 hours. There are also some that are wash out I have a blue and a white one.