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Brass plated silver turns black



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Q. I have a question of brass plating on silver jewellery and after silver plating is possible or not?

Which plating on silver jewellery does not oxidize.

Pujan ajani
- Rajkot Gujarat
August 21, 2022

A. Hi Pujan

Brass plating on silver plating is possible, but we appended your query to a thread where a potential problem with it is explained.

The best plating on top of silver, and a very conventional one, is probably rhodium.

Luck & Regards,

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


August 21, 2022

A. Brass over silver and/or rhodium over silver and/or anything else, with time (weeks) will allow the silver to diffuse thru to the top and corrode. You must have a "barrier" like palladium or nickel between.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
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A. Thanks for the clarification, Robert.
I wasn't suggesting Rhodium between silver and brass plating; to be clear I was answering Pujan's other question of "Which plating on silver jewellery does not oxidize?".

Luck & Regards,

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




Closely related historical posts, oldest first ...

Brass plated silver turns black

May 31, 2012

Q. I have a brass plating process on silver, with potassium bichromate passivation afterwards.

My problem is that brass plated article after 15 days become of a black shade.
What can I do?

Mr. Ramesh Pandit
- Surat, Gujrat, India


A. Hi,

The cause of the blacking is almost certainly due to migration of silver into the brass coating. We see the problem more commonly with silver plating on brass or copper. The remedy would be a thicker coating of brass or to use a nickel undercoat.

I am very curious as to why you are plating inexpensive brass onto silver. Would you mind explaining?

harry_parkes
Harry Parkes
- Birmingham, UK


thumbs up sign I am brass plating on silver with potassium bichromate solution because it gives rich golden color without using gold.

Mr Ramesh Pandit [returning]
- Surat, Gujrat, India

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