I have not had trouble with the blue pounce chalk. I dilute it with the white pounce (regular kind, not the iron off kind). Most of it brushes away. What little residue that remains in the quilt has always washed out for me. However, my first wash I do in cold water with NO SOAP of any kind. I then carefully inspect the quilt prior to drying. If I notice any blue residue, I give it a second wash, again no soap, cold water. I have never had a case of the chalk not coming out.
The blue chaco liner OTOH has given me trouble.