Built a 1/4 scale spacewalker and covered it with koverall. Painted it with rust-oleum and cleared it with rust-oleum clear protective covering. Flow it the other day and when I went to clean it off, fuel seemed to be sticky on the plane and did not come off with my amonia and water solution. Paint seemed to be fuel proof as it did not come off on my towel. Any ideas how to remove this sticky fuel?