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Palladium plus rhodium plating procedure for yellow gold rings

Ed. note; This is an interesting thread, and only one of many. Before you get too confused, you might want to start with our FAQ on Rhodium Plating and White Gold to get an overall understanding :-)

 
2007

! I have noted many questions on this forum regarding flaking of rhodium or other poor color results in the rhodium plating of yellow gold rings. I have personally experienced all these problems, and after much experimentation, have come up with the following procedure. I have plated six yellow gold ring sets with rhodium over palladium, with incredibly beautiful results. The process I have settled on is:

1. Buff ring to brilliant shine with brown tripoli rouge (polishing/buffing compound) [affil links], then Fabulustre [affil links].
2. Soak in 1:1 hot isopropanol:linseed oil liquid soap. Use toothbrush to clean diamonds and mounting.
3. Plate with palladium, 1 minute, 6 volts, room temperature.
4. Buff to shine with rouge cloth.
5. Repeat steps 2 - 4.
6. Soak in 1:1 hot isopropanol:linseed oil liquid soap.
7. Plate with rhodium, to a definite bluish tint compared to palladium color, about 40 seconds, 2.3 volts, room temperature.
8. Buff to shine with rouge cloth.

Two things I've learned:

1. The palladium is not only a very beautiful barrier between the yellow gold and the rhodium, but is probably the easiest thing I've ever plated. The adhesion to and color masking of the substrate are fabulous.

2. Rhodium goes over palladium better than over 14K gold, and as good as over a 24K gold underplate. Although it takes a bit longer, plate rhodium at 2.3 volts instead of 4 - 14 volts. This avoids the stress flaking you get after awhile at the higher voltages, and the adhesion is far superior. I played around a bit to find this out.

There is a difference in color between the silvery-white palladium and the more bluish-tint rhodium. However unless you really look hard, when the rhodium wears off you cannot see the difference with the palladium showing through -- a far better situation than yellow gold showing through.

The palladium and rhodium solutions I used were supplied from LDC Company, W.R. Associates, Inc.

Robert L. Nelson, Maryland
The Silver Doctor - Indianapolis, Indiana, USA

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Q. What would cause rhodium to come off a ring in flakes, I have been plating for 20 years and have had this problem before

Al Bradice
Jeweler - Stuart, Florida, USA
January 28, 2013

February 1, 2013 A. Good day Al. In my experience with jewellery, I know the rhodium deposit is extremely thin, as 0.000005". I think the "flakes" you are seeing is the underlying nickel (or other metal used to seal the substrate,and give the ring a bright ,reflective and hard coating to accept/produce a bright , lustrous rhodium deposit.) What is the colour of the underside of the "flakes"? What is the colour of the ring when the "flakes" are removed? Are you seeing base metal? I would suspect the base metal was not properly cleaned / activated for the underlying metal deposit before rhodium plating, giving poor adhesion on the base metal. Hope this helps. Regards, Eric Bogner - Toronto, Ontario, Canada February 1, 2013 A. Good day Al. I might have given you the wrong info, as you are a seasoned veteran regarding rhodium plating for 20 years. I have in fact seen the rhodium only flake. There were multiple instances. A) Badly passivated nickel prior to rhodium. These items were processed in D.I. water and left idle too long prior to rhodium plate. I do not recommend D.I. as it causes accelerated rates of passivation. B)Combination inadequate nickel preparation prior to rhodium, excess nickel brighteners (I always used cathodic alkaline electroclean after nickel plate for this reason) as overload and ORGANIC contamination. The electrocleaner will address this, providing the electrocleaner is not overly loaded with metallics/organics, as they will be deposited on the nickel substrate.As you well know, sulfuric dip after electroclean is vital to be "pristine" as is the rhodium solution itself. Metallics generally cause dull, dark deposits, whereas organics cause adhesion issues.If the flaking is not intermittent, I would carbon treat the solution @ elevated temperatures, paying close attention to carbon adsorbtion/contact time, as you know, carbon will reduce rhodium metal concentration Hope I was a little more specific. Regards, Eric Bogner - Toronto, Ontario, Canada.

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Q. Is the palladium and then rhodium plating applicable utilizing pen plating?
I like the option of selective plating yellow gold jewelry, and I would like to utilize that two-step process for increased durability.

Peter Ordon
- West Babylon, New York, USA
December 14, 2015