As a longarm quilter, I don't wash my customers quilts but I do make certain I can remove the markings I place on their quilts. The mark be gone type pen is the easiest. I use a empty water bottle and add 16 oz of distilled water (this is a must) and 1 tsp of baking soda. be sure to mark it some way or you may accidentally take a swig of it and yuk!
Then when I want to remove marks - I have an empty pill bottle the fat short kind and a childs paint brush and paint the markings. They do not come back with this formula.