Brass plated silver turns black

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,

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.

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,

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?

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