I've never had a failure with these markers, and I've been using them for years. I'm not sure how everyone else removes the marks once the project is finished, but I ALWAYS soak the project overnight. Usually, I fill my washer and add some detergent (or whatever you use), let it agitate for a minute to be sure every part of the project gets saturated with water, then turn off the machine and let it soak. Next morning, I run the washer.
I use the same method when I use the blue markers. I've ironed over both the blue and the crayola washables, as well, and the marks have always come out using the overnight soaking method.
Of course, if you have any doubts at all, take the time to test.
I had a really bad experience with them. Others on this site have had good luck. My best suggestion would be to test the fabric first. The fabric I used was by Moda and I had prewashed it. I never got it near heat, but since I was hand quilting it, the marks stayed on longer. Hope it turns out well for you. (P.S. I used the blue Crayola Washable marker)
I ironed over it once just before I put the quilt sandwich together and it came out (I used the green on "Margaret" for the first and only time so far). I don't know this would work for all fabrics or all the colors, though...probably not a good idea to do much ironing on it. A test would be a good idea.
"Neglect not the gift that is within you..." -1 Timothy 4:14
I usually use the blue marking pens. However, I need to mark a blue quilt and that means this pen won't work. I read somewhere that someone uses crayola washable markers. Can you tell me how you test for removal, etc.? Thanks!