beware of frixion pens. They iron out but reappear when the quilt is washed or when exposed to cold. I would do several tests before marking a quilt with them. If it's a small wall hanging that you will wash and iron they would be fine, but if it's a quilt that will go out of your possession and the person washes it, the lines will reappear and look terrible. That person would not know they have to iron out the marks. Test, test, test.