Marring Upper Receiver

[INPatriot]

I am putting the finishing touches on my first full assembly - stem to stern, everything. This project started in August of 2014 and I pieced everything together with what I had plus the upper, delta ring etc.

I have purchased two uppers but feel much more accomplished with the one I just finished. I only had one real hiccup and that was on the roll pin for the forward assist. I only lost two springs and got so frustrated with it I put it down last summer and just finished today. I marred it up with the ball peen hammer I was using but I was determined to not lose a third spring and I succeeded.

I think the marring looks cool. I have no intention of this being a safe queen and it will be an EDC truck gun. I just need to know what I need to put on the marred surface to ensure it doesn't rust - its down to bare aluminum. I know anodizing creates aluminum oxide, I just want to cover my bases. It was a PSA blemished upper to begin with.

Thanks

 

[CB45]

Sharpie?

Black fingernail polish?

Flat black model paint?

Is it time for a rattle can camo job?

Tagged for interest.

 

[rvb]

If it's deep enough, alumablack. If light enough like more of a rub mark, oil and rub it in. If somewhere in between, ?
It won't rust, it's aluminum. Aluminum oxide surface basically is "rust" for aluminum; it won't damage further
-rvb

 

[Mgderf]

Birchwood Casey "Gun Black" color pen.
You can get them on Midway USA

 

[seedubs1]

It's aluminum.....No need to do anything. It won't rust. Anything you do to cover up the gouging is purely for cosmetic purposes.

 

[throttletony]

correct me if I'm wrong yall, but 7000 series aluminum (i.e. 7075) can rust, even if it only stays a superficial rust, correct?

From what I remember, 6000 series aluminum is more "rust resistant" but is overall softer than 7075. Can anyone confirm?

To OP - agreed with others that it's not a big deal, alumablack or similar should work fine.
Congrats on finishing the build. It definitely has a certain feeling of accomplishment (I know it's not a big deal, but it does feel nice)

 

[gregkl]

Aluminum won't rust as in turn a dark, reddish brown color. Aluminum will oxidize which is a fancy term for "rust". In the scientific field the term "rust" is saved for iron/steel oxidation which turns reddish brown or "oxidizes".

It's not hard to cover it with something as others have suggested. Or get some oil on the spot when you lubricate it.

 

[1911ly]

If you are worried about it you can use some Aluminum Black by Birchwood Casey's. The receiver (as mentioned earlier) is aluminum. It will take a long time for any corrosion to look bad. I'd try it like it is. It looks battle worn now. It you touch it up it will look battle worn and touched up. Which look do you like better?

Take some pics. Let's see what it's like. You might be able to clean it up with a file.

 

[PGRChaplain]

Black Sharpie.

 

[Trigger Time]

Spray paint that ****!

 

[Mr Evilwrench]

The oxide layer starts forming on aluminium immediately upon exposure to the atmosphere. This is actually the biggest barrier to soldering it. The oxide layer is pretty delicate, which is why you can get electrical continuity, your probes are scratching it enough to get to metal. The layer starts out very thin and deepens over time, but the thicker it gets, the slower it goes. Long and short of it, the oxide will protect the metal, and if you'd like it to match the finish, put something black on it.

 

[Thor]

Early M16's in VN corroded to pieces. However, if you're not in the jungle you may be okay.

 

[Mr Evilwrench]

More steel parts than aluminium, the chrome lined barrels helped a lot, but no, we don't generally leave a bare surface or it does get kind of nasty. Anodizing protects very well, hardens the surface and keeps away the oxygen. I have most of the stuff to set up and do it myself now, and some dyes to make pretty colors.

 

[Thor]

I think a lot of the aluminum ended up acting as sacrificial anodes to the parts that wanted to rust.