The authoritative public forum
  for Metal Finishing since 1989
-----

Electroplating yellow gold with a rhodium solution

I already performed the experiment already. It is plating yellow gold with a rhodium solution to turn it into white gold. The independent variable is is the amount of time I let the piece stay in the rhodium solution. I was originally going to grade the finished piece (brilliant, dull, etc.), but they all look the same.how should I do the project now? what should my purpose for this be? my teacher suggested weighing it, but I already did the project and the difference between the two weight would be VERY similar.

Tina Kuo
student - Bayside, New York, United States
2006

---

Hi Tina,
I don't get the purpose of the experiment except to plate rhodium on gold. As you probably know there is a lot of difference between gold and rhodium, and you are not producing white gold by putting a layer of rhodium over the gold. White gold is an alloy of 75% gold and 25% other white metals, such as palladium, silver, zinc, nickel. Higher end jewelry companies top coat the white gold with rhodium to give it added wear resistance and added luster. Rhodium is much harder than gold. Maybe you could take weight readings at thirty second intervals in the rhodium bath to get a milligram per second weight gain. Keep in mind the rhodium solution should contain at least 10 grams per us gallon rhodium metal, or weight gain would be very minimal. If you plated inexpensive samples, maybe conduct wear resistance experiments between gold and rhodium using fine sandpaper at equal pressures. Be creative! Good Luck!

Mark Baker
process engineer - Malone, New York
2006