Based on an experience with Krylon, I'd suggest that the test not just be with raw fuel, but also holding the sample in a nice hot exhaust stream. I had a couple samples hold up to several days exposure to raw fuel, painted a plane with it based on the fact that the paint held up, only to have the paint turn into a gooey, sticky mess in just a couple minutes of exposure to hot exhaust. In fact, I didn't even get the plane launched.

Apparently, there's a difference between just fuel proof, and what Aero Gloss used to call Hot Fuel Proof.