Test markers directly on a scrap of the fabric you intend to mark. Not all fabrics will cooperate. I am presently working on 2 baby quilts that I've used the washable markers to mark borders. As soon as both are finished, I will promptly put them through the laundry. I think the longer markings are left, the bigger possibility that they will feel at home and not go away. Too, they detract from the quilting!