The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Does humidity affect rhodium?

We are manufacturer of 18K diamond studded gold jewelry. Most of our jewelry contains colored diamonds.

Since a month back, we used to give our jewelry in the market for rhodium. Now we have installed a plant. I am facing a problem with pink rhodium. It was initially coming fine; but right now, in monsoon, its giving a blackish-tint.

Does humidity affects rhodium? If yes, how do I rectify it?

Could you also provide me assistance regarding the temp and voltage I shall keep for different (white, royal gold, black and pink) rhodium?

Sudeep Sethi
- Indore, M.P., India
2001

---

It is very unlikely that humidity or the monsoon has any effect on your rhodium plating bath unless you have a leak and rain water is dripping into your bath. Rhodium plating baths have a very low tolerance for contamination so all water added must be DI water. The parts also must be free of any residual polishing compound and then cleaned and activated properly before going into the plating bath. Ordinary rhodium operates at between 2 and 10 A/dm2 and between 40 and 50 degrees C. I have never heard of pink or royal gold colors from a rhodium bath but I assume they are alloy baths like black rhodium so the current density and operating conditions should be available from your supplier.

Why are you using a rhodium bath for gold color when real gold is only about 1/6 the price of rhodium?

Neil Bell
Red Sky Plating

Albuquerque, New Mexico

2001

For your information, What is referred to as Pink Rhodium is really pink gold. There is no such thing as pink Rhodium. When you apply pink gold you have to be on a lower voltage and apply it for a longer amount of time or else it will burn

Sam Obermeister
- Brooklyn, New York
2002

---

Hi
There is a Brown/Pink Rhodium, I think Heraeus use to make; but this is for pen plating. Well, humidity can affect plating.
It will affect the working of rectifiers first, then on the connections that are part of plating process equipment.

Ravi Chandavarkar
plating shop employee - Mumbai, India
September 8, 2011