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Will age turn black anodized parts to olive drab, grayish green

If someone asks you to get them black anodized parts for non-reflective purposes and you receive parts that are 27 years old and they are olive drab in appearance is that acceptable. Is that what happens naturally? Is the anodized coating still considered acceptable, is the coating integrity compromised for its purpose or would it be considered out of specification color wise?

Janet Gardner
Receiving Inspector of Alodined parts - Eufaula, Alabama
2007

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First of two simultaneous responses -- 2007

All dyed anodizing will fade over time. The color that it goes to is dependent on the type of dye and the frequency of the light that it was exposed to.
Typically, the color is purely cosmetic and the anodize probably is OK. You can run normal salt spray tests or other QC procedures to verify the coating.
Almost all people that specify "black" anodizing want it for cosmetic purposes and OD is not black. If the contract said black, then if color is important, the lot can be rejected.
Remember, it is whatever your boss wants that is the most important factor here.

James Watts
- Navarre, Florida

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Second of two simultaneous responses --

Janet

You as the buyer need to determine if the supplied parts are acceptable.Who else is better qualified to answer that question.

It does not surprise me that a 27 year old black anodize part has faded. Organic dyes are susceptible to fading when exposed to UV. If not sealed properly, they will fade in a time period measured by days, not years.

Aside from the color issue, if the parts pass your acceptance criteria, why not use them? If you are purchasing a part, there surely must be some criteria (drawing requirements) you would use to evaluate the part.

Personally, if I paid for a black anodize widget, I would not accept it if it was not black. Maybe your supplier is colorblind:)

Willie Alexander
- Colorado Springs, Colorado
2007