I am nearing covering on my wings and noticed on a build site that the builder has primed the spars and drag anti drag tubes with epoxy primer. I can not find a section in my build manual about this procedure. I plan on using the Stewart system for gluing and painting but is it necessary to prime the spars etc. before covering?
Kitfox doesn't say it is required on the spars, but it is suggested in high humidity areas(and if you plan on using floats) so it's up to you to decide, but if you're at the stage in building where it's easy enough to do I would definitely do it as it can't hurt.
The poly fiber epoxy primer is neccessary if using the poly fiber because of chemical compatibility issues but would also work with the Stewarts system. Stewarts has their own version of an epoxy primer for metal as well. It is also my understanding that with the Stewart system you could also just use regular old zinc chromate primer which is a much cheaper option.
Of course in any case ensure proper prep. If you look up "wing spars" there are several posts explaining corrosion protection.
The local repair shop has been using this primer for years. It was about half price of the poly fiber primer and you can get it at about any auto parts house that sells paint.
PolyFiber warns in the manual not to use anything but their product due to cchemical risks (I would've done the same if I were PolyFiber...)
Have you thought of that? Or are you into chemicals (and can you help me with these same questions... Long live Internet)??
All I can say is that we have been using it for years, and it works fine. If it looks like a duck, walks like a duck and quacks like a duck, chances are its a duck.
I used both the PF and the Omni epoxies during my rebuild. They mix the same, thin the same and spray the same.
main spar primer
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