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We want our Hard Anodizing to be blacker

I found that my factory hard anodizing parts is not black in color comparing with other plating shop. I hope to know how to get more black in color? Any additive is need?

David Zhu
plating shop - China
June 5, 2008

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First of two simultaneous responses --

It may have more to do with the alloy or lot number or the heat treat state. Possibly the temperature or voltage it is anodized.

James Watts
- Navarre, Florida
June 7, 2008

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Second of two simultaneous responses -- June 9, 2008

Hi David,

The information may not be sufficient to clear your doubts. It is better if you can give a little more information like, electrolyte condition, parameters, alloy used etc...

regards

Keshava Prasada M
- Chennai, India

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In general, while there are near room temperature electrolyte additives that permit anodize coatings minimally meeting the abrasion resistance requirements on select alloys, in general they result in coatings lacking the characteristic dark near-black on 6061 type alloy. The lower the bath temperature, the darker the resulting anodize. Try a classic 32F (0C) bath.

Milt Stevenson, Jr.
Syracuse, New York
June 9, 2008

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June 20, 2008

Hi David,

As Mr. Watts wrote before, check the alloy. If it is a part coming from a die casting process, the silicon won't let you to anodize if you haven't pretreated properly the surface.

Saludos.

Guillermo Castorena G.
Jobshop - San Luis Potosí, México