Cleaning up key blank

[natas2000]

I have cleaned these with Tarn-x, Salt & Vinegar, and I put them into evaporust. Keys are nickel silver coating over brass. I don't think it's plated.
Tarn-x did nothing. The others cleaned the oil and dirt well.
But I'm seeing tiny copper pits on the head of the key. I feel that the brass may show through if I keep going with any sanding or polishing.
I like the brushed finish on the top of the key, but the cut key part that was in the lock is very shiny. So I don't know if you can tell but it is 2 finishes.
In the picture, the top has some shadows from the lighting that's not really there.

To play it safe I want to make the bottom dull. And steel wool didn't change it really.
Just don't want to mess it up. Not sure what I should do.

 

[4xdog]

Looks like oxidation through the plating in the exposed head, and original finish in the inserted blade. One of the original keys for my 1962 Triumph TR3 looks similar.

Use something coarser and stronger than steel wool on the blade. You're gonna need to get into the harder plating to dull it.

 

[RTM]

I like the brushed finish on the top of the key, but the cut key part that was in the lock is very shiny.

I suspect the bottom is polished or abraded from being inserted into the slot regularly (get your minds out of the gutter). To get the top to match, you might have to use abrasives on it. To get the bottom to match the top, let it corrode without using it to wear off the corrosion effect.

 

[RoninB4]

-If it is copper showing it's used as a flash coating for the plating to stick to. Even nickel can be just a flash coating, further abrasive cleaning may just rub through.

-Interesting, to me, side note is the lettering at the top stating Selma, Ala. as the origin. Selma was the scene of a pivotal incident from the Civil Rights movement. I was also stationed in Selma while in the Air Force.

 

[Nick Rivers]

Rotary or Vibratory tumbler like the ones used for cleaning ammo brass.

 

[humber2]

I’d try phosphoric acid, most rust killers use it as does coca-cola.

YMMV