Salut!
The most used Luftwaffe paints were not epoxy nor nitrocellulose.
Flieglack 7012 and 7122 were both based on phenol resin ("
Phenolharzverkochung in aromatischen Kohlenwasserstoffen") and Flieglack 7155 was based on polyvinylchloride (
"Polyvinylchlorid und Antimon in aromatischen Kohlenwasserstoffen").
See documents:
http://www.rlm-farben.de/en/products...-coatings.html
(Kiroff paints)
Phenol resin is inherently flame retatrdant. Antimony addition probably does the same for the polyvinylchloride.
Of course there was other paint systems used on Luftwaffe planes. Although I certainly do NOT remember any epoxy paints. It would have been poor choice anyway because it chalks easily outdoors. Compare some modernish sailplanes like SZD Jantar.
Cheers,
Kari