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Electroplating gold with an alloy of copper and silver

I am Padma from India with no knowledge of electroplating. I have seen people electroplating from rectifiers with gold in one end and the jewellery on the other end with some chemicals in the liquid. I want to know if it is possible to electroplate 22 ct yellow gold with an alloy of copper and silver 8:2 ratio in this technique rather than the gpc technique. I have mailed to you before but with no answer. Kindly requesting you to consider this question and reply. Looking forward to your reply

Bye

Padmanava Jethy
plating shop - Cuttack, Orissa, India
2006

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Hello, Padmanava. Plating of alloys can be very difficult. What happens is that the more noble plates out almost exclusively and virtually none of the other metal will plate out (see the Nernst Equation). To achieve alloy plating requires the use of specific complexing agents that tie up the more noble metal and prevent it from plating out. Such complexing agents exist for some alloys, whereas other alloys may be impossible. While it might be possible to get a "goldish" color from a copper-silver alloy, I don't know how that alloy would be plated, or even if it can be -- let alone whether an 8:2 ratio is possible or best. Hopefully someone else will comment on that.

As you claim that you have no knowledge of electroplating, please postpone trying to plate difficult alloys until you are proficient with plating simpler pure metals. Proprietary plating solutions rather than home-brew are probably the only answer to difficult alloys anyway. That may be why no one answered you last time. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006

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First of two simultaneous responses --

Could it be just a mis-spelling error and Mr. Jethy refers to plating ONTO copper-silver and not WITH copper-silver? He mentions to have seen the gold in one end (anode) and the jewels in the other (cathode). If so, then he's looking for gold plating technique.

Guillermo Marrufo
Monterrey, NL, Mexico
2006

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Second of two simultaneous responses --

Padmanava,
I agree with Ted that you should familiarize yourself with decorative electroplating first before you try to tackle color or alloy gold plating. I don't know what you mean by 8:2 ratio vs PGC. Color or karat golds can be plated from a cyanide based solution (containing free Cn) or a acid gold. It would depend on the gold thickness you desire, and how fast you want to achieve the desired thickness. Color or "flash" golds plate 3-5 microinches fast. Acid golds take a little longer because of the make-up or conducting salts and lower ph. I like a cobalt brightened acid gold ran at 1/2 tr. oz /gal gold metal with the ph at 4.2. Technic, Inc. has a workhorse called Orosene 999. Very stable and easy to run. A rich 22k color or alloy can be achieved with this bath. Good Luck!

Mark Baker
Process Engineer - Syracuse, New York
2006

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Padma,
Please leave the R&D job to the manufacturers.There are many and some representation is there in your city.
They will guide you to buy the best proprietary formulations of any karat you want.
Regards

T.K. Mohan
plating process supplier - Mumbai, India
2006