One of my first quilts I used yellow chalk to mark my quilting on blue...sad to say, but 3 years later the yellow chalk is still there. I've learned to be very wary of what I mark my quilts with for quilting. I use white as much as possible or the graphite (gray) of Sewline that I can erase or wash away. I'll be interested if you can find a way to get rid of the yellow...my yellow disaster is on my first applique project that I designed for my parents and I would really like to get rid of the yellow.