Where the
world gathers for metal finishing
Q&As since 1989


-----

How silver plating is done

I am doing a report on how silver plating is done but I'm a little stuck. I don't know where to look for information at. I keep looking up things but nothing is giving me what I need. what are the ingredients to making the solution? does it take a professional to do it. how is it done? thank you very much.... oh yea I am in 11th grade

sarah j
- Providence, Rhode Island, United States
June 11, 2009

---

June , 2009

Hi, Sarah. The jewelry or flatware or whatever is cleaned, then put into an open top tank full of silver cyanide electroplating solution (the formula for silver cyanide electroplating solutions hasn't changed in over a hundred years, so any book you can find at the library will still be right).

The part is connected to a rectifier, i.e., a source of low voltage direct current, and is made cathodic (negative), while silver chunks are made anodic (positive). The rectifier, connected to the parts and the silver chunks by heavy copper bus bars, pulls electrons from the silver and drives them to the part that is to be plated. To "catch up" and balance out this displacement of charge, the silver metal is changing to positively charged silver cations which dissolve into the solution, and migrate over to the negatively charged part. When they reach the part, their electrons are again available, so the silver cations are reduced back to silver metal, and deposit onto the part.

How many electrons you move determines how much silver you move (plate out onto the parts), and this relationship is expressed by Faraday's Law of Electrolysis. 96,485 ampere-seconds of electricity will deposit one gram equivalent weight of metal, which in the case of silver with an oxidation state of '+1', is one gram molecular weight.

All practical decorative silver plating baths are cyanide based, which is a very powerful poison, so the process should only be done by a professional. You can do experimental electroplating of other metals though, as described in our FAQ, "How Electroplating Works". Ace it.

Regards,

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