[ARC5] Greenish-yellow powder on aluminum connector shell

[Dennis Monticelli]

Hi guys,

Maybe someone here can help me identify the "corrosion" covering the
aluminum shell of some WW2 connectors.  It is a mostly yellow (with some
green in it) powder that will come off on your fingers if yor rub.  Cleaning
with an amomnia product (Windex) can remove nearly all of it.  My guess is
that the connector was coated with something that contained some zinc
chromate and the coating has broken down thus releasing the zinc chromate
crystals which have that color naturally.  The aluminum itself is mildly
corroded but not pitted.  I know that zinc chromate was widely used on
aluminum aircraft materials in WW2 as a paint undercoat.  It had a
pronounced yellowish color.  But whatever was on these connectors was not a
paint per se, but ratger a thin (probably) translucent coating of some
kind.  I guessing the coating had some, but not a lot, of zinc chromate in
it.  I am not aware of any corrosion byproducts of raw aluminum that would
produce this yellowish powder.  Perhaps this aluminum is of an alloy that
would create the colored powder naturally over time.  Another bit of info
for you sleuths is that the connector was stored in the equipment's original
wooden case for most of its life.

Dennis AE6C