80% Lower Finish

[prepare]

What can I put on the milled portion of a 80% lower to keep the aluminum from oxidizing? The outside is already anodized.

[MistWolf]

You want the aluminum to oxidize. It's that naturally forming layer of aluminum oxide that protects aluminum from corroding. Anodizing is a process that converts the surface aluminum to aluminum oxide deeper and more uniformly than the material process.

You could apply Alodine, a chemical conversion coat. It's not as good as anodizing, but better than the natural process.

[ABNAK]

Duracoat or even spray paint in a pinch. I'd bake either one to harden it though (correct Duracoat application calls for baking anyway).