Thanks Pamar for the suggestion of using the Mr. Clean Magic Eraser. Between that and using a toothbrush it got 98% of the blue line out. Just a couple of small spots left. Luckily this is a quilt for my 6 year old granddaughter so she won't be to critical. I will be more careful on what I use next time. By the way, I had trouble with some lines on fleece. also. This same process helped a little but not much. Need to find another marking tool for fleece next time.