Boss248 - I've used poly on several planes and not had a problem with it. It is not 100% fuel proof, but raw fuel has to sit on it for a while before having any effect. Hot exhaust doesn't touch it. Just don't dump raw fuel on your plane and leave it there and you won't have any problems. I've never had any poly on my planes become damaged from fuel. The only damage is directly under my fuel jug in my flight box.

- Paul