Variprime works just fine... It contains zinc and is a corrosion
inhibiter... It is hard once cured... While it may not be as
impermeable to moisture as some topcoats, unless you are immersing the
plane in the ocean, it is good enough...

Now if you are doing the interior of an assembled aircraft where the
fayed joint surfaces cannot be coated, why not skip the work and cost
of a primer and just fog the metal with ACF50 every other year?

denny