43074

Resistance of Rhodium Plating [Denmark] 

November 17, 2006

Rhodium can wear off gradually on rhodium plated silver jewelry. It is said to depend on the plating thickness and the actual "wear" the jewelry is subjected to how long it takes. Is it possible to explain a little about the relations betwen thickness in micron and resistance to wear.
What thicknesses are primarily used for rhodium plating of silver jewelry (rings and bracelets).
Does Platinum plating generally provide a better resistance against wear as Rhodium - or the same.

Kind Regards,

Knud Torbol
- Denmark

Hello Knud,
It has been evident that a thicker Rh deposit will wear longer. As far as specific wear cycle testing based on thickness plated, I don't know of any tests conducted with conclusive results. It's hard to define "wear". Is a farmer going to wear the ring, or a computer programmer? The common Rh plated thickness in the jewelry industry should be .05 - 1.5 micron. Being that Rh is so expensive the thickness is usually on the lower part of the scale. A Rh plated deposit is harder than Pt, so Rh would have better wear resistance. If going over Ag I would plate no less than half a micron. Good Luck!

Mark Baker
Process Engineer - Syracuse, NY, USA

Rhodium plating is usually in the neighborhood of .1 to .2 micron and naturally thicker deposits will wear longer. Platinum and Rhodium and similar metals and share many properties.

Neil Bell Red Sky Plating Albuquerque, NM, USA

It is extremely difficult to electroplate rhodium without stress cracks. The silver migrates right through the cracks and the corrosion eats away underneath. You have two choices. (1) Buy your Rhodium Plating process from a vendor who has a stress reducer in the formulation and keep the whole preparation process perfectly clean. Or (2) put a difusion barrier between the silver and rhodium: use paladium or nickel.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

Silver Rh plated jewelery it is giving problem later on, when Rh comes off then it's difficult to strip Rh and undercoat is done by Ni it's hard to make new brand. I'm doing this kind of stuff. I advice to do clear coat which is best lasting longer.

Dipen Pattni
jeweler/goldsmith - Dar-Es-Salaam, Tanzania