Birchwood Casey Aluminum Black

[kilotanker22]

I believe that Cerakote or Duracoat would offer a superior finish to the blackening agent used.

 

[Ricklin]

Uhh, do not leave it like that, yes it is polished, it is still raw Aluminum. Have it anodized or paint it, raw Aluminum requires a finish.

 

[Bill DeShivs]

Aluminum doesn't "require" a finish.

Aluminum produces it's own layer of aluminum oxide when exposed to air. This prevents it corroding or discoloring.
I have pistols with raw aluminum frames that I have owned for decades and they still look like new.

 

[Unclenick]

I've seen aluminum bloom white oxide clumps, so I'm not convinced that the fast-forming surface oxide layer is always adequate under all conditions. But raw aluminum that gets rubbed with a silicone rag or gun oil or such will probably do fine.

 

[Ricklin]

It will really depend on the environment. One of my homes is close to the ocean. Salt air and raw aluminum, no thanks. In my world Aluminum must have a finish.
YEMV Your environment may vary.