Nelson Hobby Specialties offers a water-based clear coat in flat. If used with the extra crosslinker, it is said to be absolutely fuel proof. It's a little pricey, but is said to go a long way. I ordered some for a project I am currently working on, but since I haven't gotten to the finishing stage, I can't speak from personal experience yet. I have read good reviews, however, which led me to purchase it. Good luck, Dzl