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Need to conventional anodize areas of hard coat anodized part

I have some parts that were hard coat black anodized. We later machined some small areas due to a design change. The reworked areas do not need to be hard coated, but should be black and anodized for corrosion reasons. Can the unprotected areas be black anodized with a conventional anodizing process without stripping the hard anodized areas?

Kerry Murphy
- Lynchburg, Virginia
2005

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First of three simultaneous responses -- 2005

Kerry

You should be able to have the bare aluminum surfaces anodized, conventional or hard, and dyed black. If the original coating was sealed properly, you should get decent results. If not, you may have to buff the original surface after the second coating.

You'll need to specify whether or not to seal the second coating, based on the initial coating requirements.

Willie Alexander
- Colorado Springs, Colorado

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Second of three simultaneous responses --

Check out letter 36552, it should answer most of your questions pretty well.

Jim Gorsich
Compton, California, USA
2005

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Third of three simultaneous responses --

YES, if you can make electrical contact. Clean in dishwashing compound, skip the etch, scrub with Scotchbrite, deox in the anodizing tank before turning on the power.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005