I've doped over fiberglass/epoxy on two planes. It seemed to work well over sanded surfaces and has not lifted or otherwise come loose from my profile fuselages. BUT on the last stabilizer, my clear Brodak butyrate did bubble up in places after a few days at the field. I think it will stick, if I clean it up some and re-do it. Maybe it's vibration in that part, because the two fuselages are just fine after a couple years.