Aluminum cold blueing...?

[Vin63]

...hard anodizing.

This would be the best option for aluminum. I've had black anodize done to polished aluminum parts (AN fittings, brackets, etc.), including wheels, for projects that turn out fantastic.

[Nathan Krynn]

OP wants a DIY coating that requires no toxic acids, not send it out to someone else.

air cured Cerakote would be the most durable non anodized type coating you could put on an Aluminum lower yourself without fancy setups.


If you want it just black then you can buy metal marking ink and pour it over the lower.

Better j/k answer than the high temp grill paint my hillbilly butt was going to suggest.

Sadly I have seen that used on even suppressors.

[wpage]

Rust O Leum works too but not for long...

No magic pill here.

[wpage]

Aluminum is soo soft it wont really take much of any....

Maintenance is required since its not hard steel.