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Mil-Spec for Coating Thickness for Anodize

I am new to plating and am a bit confused about the anodizing mil-spec. As I understand, the anodic coating is both penetrated into the part and built on the exterior surface of the part for total anodic coating thickness. Does the mil-spec refer to actual exterior build or the total thickness inside and out?

K Carr
- USA
2001

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2001

You'd need to cite the particular mil spec and paragraph for us to be absolutely certain, but I'm quite confident they are specifying the overall anodized thickness, not one component of it.

At the risk of over simplification, what happens in anodizing is that the aluminum surface is converted to aluminum oxide. All of the aluminum in the aluminum oxide coating comes from the conversion of the substrate itself--it is not a 'plating'. But each molecule of aluminum oxide that is formed occupies about twice as much volume as the atom of aluminum that went into it.

So, it's not like you have two different layers in the coating.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey