I made this rag quilt for my oldest son's toddler bed, and was sad to find a huge blue marker stain on it several years ago. I tried hairspray on the stain, which only seemed to spread the blue around and not remove any large quantity of it.
It has been in my stain removal bucket for years and I finally decided to throw it out. My mom stopped me and suggested I try hand sanitizer.
Hand sanitizer is mostly alchohol, like hairspray, which is it's stain removing ingredient. Unlike hairspray hand sanitizer is a gel and stays in the stained area to deeply penetrate and remove. Since I had left the stain so long and probably washed and dried it, it didn't come out completely, but it is enough improved that it will work for an outdoor blanket.
The bonus: while I was working on the quilt all the paint stains on my hands came off, grin.