I think a lot depends on whether you intend to prime it yourself and what protective equipment you have. My understanding is that many of these substances are truly nasty… For something that’s internal, does it matter so much?
Personally I tend to use Tetrosyl etch primer after scuffing the aluminium with Scotchbrite and degreasing with Acetone. You don’t want to scuff alclad too vigorously or you will rub through the pure aluminium layer that protects the more vulnerable alloy beneath.
I gather that you then need a thin coat of something harder on top both to seal the primer and to provide some protection from moisture. But I’m not an expert… Part of the reason I’m putting this forward is for somebody to put me right if I’m on the wrong path. But when I looked into it it did seem a safer substance than many of the alternatives.
At Vans Air Force there is entire section called “primer wars”. Every single builder has it’s own opinion regarding priming of internal parts. The only general thing to say about it, is the rather disatisfying: it’s a personal thing, do whatever makes you feel OK.
That’s a cessna but I guess what you call primer is this yellowish paint ? Our mechanics spray it outside with a mask. Everything accessible is sprayed because our planes are parked outside.
Best thing for outdoors is ACF50. OTOH you can’t apply it in the cockpit area (always liquid, etc).
But yes the yellow/green is a primer. Internally it is mostly left without additional paint applied.
Jujupilote wrote:
I guess what you call primer is this yellowish paint
Considering true anti-corrosive pigments are used (that this is not some “look alike”, which it very well might be), that yellow is strontium chromate. That greenish is zinc chromate.
The whole subject of corrosion protection is a lot deeper than just what to spray on a bit of alloy sheet, take a look at FAA AC 43-4B to find out far more than you ever wanted to know.
We used EP420 epoxy primer in our RV10. It comes in White or Green, and we bought it from http://www.aircraftcoverings.co.uk/
This RV14 build is worth a read. They are using Ekocrylic from Stewart Systems. Whether you can get it where you are is another matter.
Why they chose it I don’t know. @jwoolard may know more.
