This is copied from Nancy Prince Newsletter.
"I would like to add one other comment that was sent to me by Kay S. Kay told me that she used one of the new pens on batiks and when she ironed it, it took the color out. I tried this myself and got the same result. If the line is drawn very faintly, then the color does not come out but if the line is drawn so you can actually see it, it did in fact take the color out. Just thought I would pass this along to you."