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plating, anodizing, & finishing Q&As since 1989




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Sticky film on my black anodized 6061

2006

I work for a small machine shop in DE that makes aerospace and lasers. A lot of our parts get black anodized. We started with a new plater and have been back and forth with different problems, the latest one involves a sticky film which I believe to be a post treatment problem. I need to go there and would like to know where to start.

Chuck Wieand

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First of three simultaneous responses -- 2006

It is because of poor sealing: temperature, time, PH value as well as Aluminum hydroxide content related.

John Hu

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Second of three simultaneous responses -- 2006

Most often, an anodize coating that is sticky means it is not properly sealed.

Very basic mistake - would not give me much faith in the finisher.

David A. Kraft

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Third of three simultaneous responses -- 2006

Get a copy of the specification that they are anodizing to - usually this is MIL-A-8625 / MIL-PRF-8625 [affil link or DLA] and there are links to get a copy from the home page of this site. Read that spec, then check to make sure that they are following it.

If they aren't working to a specification, the place to start would be on the job shops list looking for a new anodizer.

Also, very few post treatments would give a sticky film purposefully, and almost all would be done with the customer's knowledge and with an extra expense - However, failing to seal the parts can give them a sticky feeling, so look carefully at that step as well.

Good luck!

Jim Gorsich
Accurate Anodizing Inc.

Compton, California, USA