There is a recipe for this but its on my pc at home. I do know that when you use the blue marker it is suggested to soak it because the marks or remnants of it will show back up. So at least soak it in cold water, I do mine for at least 15 min. I have used it on starched fabric before without any problems; no heat or starch after the marker though. I'll try and remember to get the recipe. I think it had baking soda in it. Can't remember, it's been a few yrs

This has happen to me!! I googled "brown marks on quilt". I got instructions for washing the quilt in a Mixture of white vinegar and water. I have forgotten the exact mix but I think I used at least two gallons to a washer full of water. IT WORKED!, I thought the quilt was ruined so I went for it!! I was amazed. My mistake??? I washed with soap and oxyclean. It caused a chemical reaction with the blue marker. Now I soak in water til marks are gone. Then I wash with soap. No oxyclean. I was saved. Hope you are too!

Thanks everyone.

Try washing it in Baking Soda, this should nutralize the blue marker on the quilt. There is also a new bottled solution to wash the blue marker out of textiles, it is called Blue Line Remover and understand it is available on the internet.

I just had same problem with a tablerunner cream print fabric I even did a test on an extra block came out fine on the test but after I did the actual quilting on the runner I didn't come off from the stitching the thread it self I sewd directly on top of the blue line so I don't know.... and it was 100% cotton thread came off the fabric but not the stitches