Aluminum and salt

I need a lesson in chemistry to understand the reaction salt has on aluminum, if it has any reaction at all. I’m not sure.

There’s so much conflicting information out there.  Is it a form of rust? Is it some protective coating that’s being formed? Do I let it do its thing? Do I use acid to get rid of it?

Isn’t using acid on aluminum like sanding a wood floor? You can only do that so many times.

What to do, what to do.

Fred, what do you think?

-Leah

Editor note:  Dr. Fred is a chemist, and you've probably used a thing or two that he patented. Here is his response.

Aluminum is lucky to be here. It is an extremely reactive metal and the only reason it does not quickly disappear is that it forms a protective layer of aluminum oxide when exposed to air. Normally the coating is too thin too see. Salt catalyses the formation of the layer and allows oxygen to get deeper into the aluminum and make lots of the oxide. That's the grey crud.
Acid will dissolve it but also attacks aluminum very rapidly. I would not use it. Just brush, sand, scrape the crud off. Rinse well with fresh water once you get away from the salt air. Then a light sanding or steel wooling (did I invent a word?) will restore a nice look. You could go berserk and use a buffer and polishes.

  Fred