[VAL] Discoloring on exterior aluminum surface

["Forrest McClure" <rollie51@xxxxxxxxxxx>]

Discoloring is very hard to remove because it is a chemical interaction 
between the aluminum and staining agent. It can not be polished out unless 
an aggressive grit is used and then that has to be polished smooth again. 
I've used Aluminum Naval Jelly on some small stain areas where the rust 
from a steel rivet or screw (put there by either a PO or Airstream or a 
repair shop) leached into the surrounding aluminum surface. The Naval 
Jelly removed the discoloration so well that it left its own discoloration 
- brighter, whiter aluminum than the surrounding surface. However, the 
brighter bleached out look is better than the rust stain. Anyway, Aluminum 
Naval Jelly might work to take out other types of discolorization. Try it 
on a small test area first though to see if the results are acceptable. 
Aluminum Naval Jelly is different than regular Naval Jelly. The first is 
blue in color formulated just for aluminum and the later is red in color 
formulated just for iron and steel.

Forrest