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Metal Cosmetic Finish Issue : Steel Washer with Black Zinc

2003

Q. Dear Sir, My company is distributing-supplying a Steel washer in Black Zinc to a lighting lamp manufacturer. The washer is a large 1.5" outer diameter with a 1/10" thickness. This is a cosmetic part for our customer.

The customer have been complianing that the black zinc is not perfect black and has rainbow like colours on the surface of the black zinc. We have tried to minimise and to prevent this and rework but has not been successful.

22556

Can someone help me suggest alternative coating, plating or painting, or other process that we should take note of to have a perfect black colour steel washer. I welcome any known source or referral to solve these cosmetic problem.

Thank You. Ronnie Tang

Ronnie Tang
EXIM & MFR ENTERPRISE - Singapore

A. My suggestion, Mr. Tang, would be to consider switching to zinc-iron plating. It readily accepts a stable black chromate.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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