[Roger]

Hi Del,
Roger likes and uses acetone....very carefully!
Bill Hansen does not like acetone, and suggests lacquer thinner, mineral spirits (paint thinner) and Goo Gone.
I'll have to try the lacquer thinner, but I've always used acetone, and it works great, but don't get it anywhere near a seam, as it will melt the glue that holds the sail together.
Also, use it very sparingly, just dampen a cloth or paper towel and wipe the number or gooey area quickly.
DO NOT allow acetone to "pool" on your sail as it will quickly eat through the monofilm or x ply scrim.
Hope this helps,