Chris
People use all different types of paints. A lot of it will depend on what you are powering the aircraft with, not all varnishes will tolerate petrol or glow fuel. I know of some people that use the Ronseal Diamond hard clear varnish, applied by roller , on petrol powered warbirds and they have found it petrol resistant. I did a test peice recently and found that although you can spray this varnish it needs watering down by around 50% at which point its not petrol resistant. If you have electric aircraft or gliders then I would suggest this is a good varnish to use at it remains flexible and gave good results through the airbrush.
As an aside, I am currently using cellulose paints bought online and they spray really well and dry really fast, although petrol proof in its own right I have also given the planes a coat of cellulose clearcoat for added durability.
I use filler primer as it is much better at dealing with slight imperfections and just sand it well back.
Edited By Patrick Marsden on 22/04/2020 13:36:45