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Tiny spots on parts are not anodized

I have this part that is 6020 alloy. After anodizing and dyeing black, there are very tiny spots that have no dye. This is in a critical area of the part and not acceptable by our customer. Any ideas why this happens? I feel this area may not be anodized, could this small of area not get anodized?

Stephen Gibson
Production Manager - North Tonawanda, New York
June 15, 2011

Hi, Stephen.

The anodized film is a very high electrical resistance coating that is created by putting electrical current on the part. Thus it is not possible to anodize a part and not have small bare areas (contact marks). The problem here was apparently the failure of the customer and the anodizer to agree on where those spots should be located on the part.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 16, 2011

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