Many different blends, many different properties. Many soften with heat, and most of the more comman types used by modelers are not glo fuel proof. They are very glo fuel resistant. CA is also not fuel proof. Any body that thinks different can prove it, to themselves, simply by coating the inside of their favorite planes fuel tank with their favorite brand of epoxy. Let it cure. Happy dead sticking. Why does it work on firewalls as protection from fuel? "All" of the fuel components do not stay on the surface long enough.
Ed M.