I've had the same experience. Our little quilting group conducted our own experiment and found that, yes, it does leave a ghost line. I think you have the impression that the line fades on a quilted top after washing. But we tried everything kind of washing product we know of on unquilted fabric and the line remained. That said, I still use the pens. My quilts don't go to people who get out their magnifying glasses to check for lines.