have you pressed your marks? (heat set them)???
for some reason the yellow seems to be the most difficult of the chalks to remove-
generally an eraser- or brush will remove chalk-
some people have had luck using a 'magic eraser' too
an oxyclean paste rubbed into the marks then rinsed out has also been used with success.
i personally use chalk all the time and have never had any chalk marks remain after laundering the finished quilt-
when i finish binding my quilts the very next step is to go into the washer- normal cycle- warm water- normal detergent- and i wash it- then i toss it into the dryer & dry it- if i used alot of dark batiks and am concerned about color running i use cold water & toss in color catchers- or use synthropol---that is about the only (special) steps i ever take- figuring whom ever is going to recieve it is going to launder it like anything else- i make sure it's going to survive that.
