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Trivalent silver plating

Q. Dear All,
Greetings, it would be a great help if anyone is able to clear my doubts; today I heard a requirement from one of my customer for trivalent silver plating. I have two types of silver plating with brightener and without brightener, even I searched in google for the same but I am not able to get it, please help me in knowing this new technology in our electroplating field!

Raja gopal
plating shop employee - India
January 23, 2010

A. Hi, Raja. I doubt that there is a trivalent silver plating process. But consider this: the world has largely moved away from hexavalent chromating of zinc and zinc alloy plating and towards RoHS-compatible trivalent chromating. Black chromates often have silver in them and I suspect that your customer is confusing this silver-bearing black chromate with silver plating.

Alternately, there are many ways to provide an anti-tarnish treatment to silver plating. One of the traditional ways was with a hexavalent chromate anti-tarnish treatment, which is probably not RoHS-compatible.

Please try to get a detailed report from your customer about what he is trying to say. Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 26, 2010

January 27, 2010

Dear Ted,

Thanks for your information, I too suspect that my customer would have got confused with the trivalent chrome and silver,

regards

Raja Gopal
- India

Chrome-free low resistance anti-tarnish for silver

Q. Hi All,

I am looking for a low electrical resistance chrome-free anti-tarnish treatment for silver plate.

David Millward
- Montreal, Quebec, Canada
July 1, 2014

A. Hi David. That one sounds easy because I can't think of any alternative to rhodium flashing/plating :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 2014

Hi Ted,
Thanks for the quick response although it is not what I wanted to hear. I thought I had read somewhere that a trivalent conversion coating for aluminum ( like Surtec 650 or similar) might give some measure of shelf protection on silver and possibly copper plating. Oh well, back to the drawing board.

David Millward [returning]
- Montreal, Quebec, Canada
July 1, 2014

A. Hi. I too have heard vague rumors of the NAVAIR TCP coatings for aluminum being repurposed for use on other metals, so maybe they can "give some measure of shelf protection" to silver. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 2014

July 22, 2014

A. Hi David,

There's cadmium free, low electrical resistance post treatment chemical (so called pore blocker or anti-tarnish) available in the market to seal deposit porosity and form a hydrophobic film on silver to minimize moisture and/or sulfur containing environment attack to cause silver tarnish. The treatment is just a post immersion dipping after silver plating.

Regards,
David

David Shiu
- Singapore

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