That's the standard technique for aircraft work on aluminum.

From http://www.aircraftspruce.com/catalog/cspages/zinc.php

ZINC CHROMATE AND ZINC OXIDE PRIMERS
Maximum adhesion to bare aluminum and steel
Tempo's Zinc Chromate and Zinc Oxide Primers are recommended for priming
bare metal. These primers provide maximum bonding to bare aluminum and
steel. Tempo's Zinc Chromate has been the workhorse in the aviation industry
for many years, while Zinc Oxide has been recently introduced to provide a
"safer, healthier" alternative to Zinc Chromate with equal performance.

I've bought my spray cans at the parts department of my local small airport
FBO.

Roger

http://home.insightbb.com/~derbyrm

"ray lunder" wrote in message
...
It has some kind of plated gold finish on it that's streaked and faded
in kind of a tiger stripe effect. Someone said I have to sand and coat
with zinc chromate and then paint it with whatever I want. Has anyone
tried this? Thank you.