American Society of Portrait Artists
The American Society of Portrait Artists, the largest portrait artist patron organization in the world, is an international association dedicated to furthering the fine art of portraiture and supporting the individual artist. The Society is lead by a distinguished advisory board of directors, all dedicated to developing an agenda that will increasingly provide every possible resource for serious portrait artists. The Society provides a means for networking with portrait artists and is a forum to provide valuable information, research materials, and links to seminars.
I like the White Galaxy Marker very much for writing on dark paper, and I have used it to cover another color when I needed to disguise a mistake or simply change effect.
For example, I bought an ornament with name SCARLETT spelled on it and by covering the last 't', I was able to give this to someone with a cat named SCARLET.
If color to be covered is a paint or other pen color, that can make the other color "stain" the white marker tip. This can be avoided if one is sure first color is dry before trying to cover it with white.