Friday I sent into my LQS, they were demonstrating a new marker ink pen- and had kept one aside for me - all stock was sold out immediately - I just needed to share this information with you - it is a pen made by Pilot called "FRI X ION" Ball - remove by friction. They come in a variety of colors as well, but don't remember which those colors are. I can think of all sorts of uses for this pen.
I wrote on a piece of white cotton, then took my iron and when I placed the iron on the mark - it totally removed the mark - I thought I should try it on a quilt I am making for my neice - now who would mark their new quilt? Again it removed all traces of the ink and no marks at all today on my quilt.
See pics attached.