If you have any of the fabric, make a test sample and try out some of the things mentioned. I don't have anything else to add. I used blue marking chalk on a white quilt years ago. It has been washed a lot and I can still see it in places. It came out of the fabric but the cotton white quilting thread picked up the blue and it's still there. Luckily it was just for myself so I just "chalked" it up to experience. I haven't used it since.