Tartan

Not only can coloured chalk stain your fabric but it can be observed into cotton quilting thread. The blue chalk I used on a quilt many years ago is gone from the fabric with the repeated washing but the white quilting thread still has a blue tinge. Try different cleaning solutions on scrap fabric to see if you can get it to fade enough that you can live with it.

LilaMarlene

I just successfully used Zep Industrial Strength Degreaser spray. Wet the area with cold water, spray generous amount of Zep, scrub gently for a couple of minutes, rinse, repeat if necessary. Worked for me!

quiltingshorttimer

Try some SewClean--I had my LQS order some for me but also Jamie Wallen sells on his website.