I love the frixion pens too, but it was recently brought up at class, that the mark reappear when the quilt gets below freezing. So one of the ladies tried it. Yup, when the quilt got cold the marks reappeared even after laundering a few times. They are a great aid, but beware, if someone leaves a kid's quilt out in the car when it's cold, the marks will reappear. But they will disappear again after ironing . Supposedly it says this on the packaging.