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Blue Dye coming off anodizing

August 26, 2019

Q. Our anodized product is done by a subcontractor. Our customer hasn't changed his manufacturing method with the parts in over 30 years, but this is a new problem.

Part is 6063 - 202 R1 Etch Blue

When he runs the parts through the normal roller he has used for decades, the blue is scraping off. Samples were sent to us and we can scrape more off with soft fingernails along the edge. Thinking it maybe a seal issue, parts were sent to the anodizer - whom says the anodizing and the seal are fine. Anything else to test for?

Dianne Mickey
Buyer - Winton, North Carolina

A. Hi Dianne. Anodizing dye is not something that goes on top of the anodizing, but it goes into the pores of the anodized coating, and then the tops of the pores are 'sealed'. Thus I doubt that the dye is coming off and the anodizing not. Do you have any samples that you can scrape the blue dye off of that have have not gone through your customer's rollers?

The first question I would have is what the parts look like before the rolling operation. It sounds to me like something has changed dimensionally with your customer's rolling operation such that it is shattering the somewhat brittle anodized coating.

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 2019

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