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Rhodium plating Q&A, woes & problems



A discussion started in 2001 and continuing through 2017 . . .

Rhodium plating problems, brown spots and fog

(2001)

Q. Occasionally, when I do rhodium plating, I get tiny brown spots on the metal. Other times I get some "fog". I have my rhodium solution checked regularly, and replace my electro-cleaner regularly. Any ideas as to what may be causing this and how to correct it?

Howard Kelrick
- Hollywood, Florida


(2001)

A. Usually brown spots mean that acid has been absorbed into tiny crevices, pores in the base metal, only to leach out after plating and drying. Use less concentrated solutions, less porous metals, and flush porosity with hot and cold rinses.

tom pullizzi monitor
Tom Pullizzi
Falls Township,
   Pennsylvania 




Jeweler has rhodium plating problem: burning of tips of claws

(2003)

Q. I am a jeweler and was wondering if anyone has any explanation for the following. Could someone please explain why when I rhodium plate a white gold claw set ring, why do the tips of the claws become blackened. (Burnt in the process of rhodium plating?) Particularly when we are masking off to rhodium coat two-tone pieces of jewelry. We are using 6 Volt battery charger on low end.

Any help/suggestions would be appreciated.

Andrew Dutton
- Cairns, Queensland, Australia


Rhodium Plating System

(2003)

A. Because your voltage is too high. Get a better power supply.

James Watts
- Navarre, Florida


(2003)

A. Six volts is too high for rhodium, particularly if you are plating one ring at a time. Yes, you are "burning" the prong tips, which are a very high current density area. The current needs to be below 60 ASF and on a single ring this is only about 0.3 or 0.4 amps. Less if you are masking some of the surface.

Neil Bell
Red Sky Plating


Albuquerque, New Mexico




(2003)

Q. Hello,

I'm hoping I can get some advice about plating.

Let me go straight to it: I sometimes need to rhodium plate, or yellow gold plate jewelry (mostly watch cases) items. I bought a 25 amp plating machine, along with rhodium, copper, nickel and 18k yellow solutions, plus all the correct anodes (platinized titanium for rhodium, the one that looks like a grille, from a supplier in Los Angeles).

My first 2 items to plate were a white gold watch case (to be first nickel and then rhodium plated), and a sterling silver money clip (which holds a silver coin, to be first copper and then 18k yellow plated).

I perfectly polished both items (really removed the old rhodium), had them in the ultrasonic (used magic green) for 25 minutes, and steam cleaned them until they were red hot, the items were clean.

After that I wrapped them with watch paper (didn't touch them with my bare hands at all), left them untouched for a few days, and proceeded to plate them.

Using thin latex gloves I attached 14k gold wire (yellow for the money clip, and white for the watch case) in a way that there was good electrical contact.

I first nickel plated the watch case, and copper plated the money clip; then I proceed to rhodium plate and 18k yellow plate them respectively.

I used a pint of solution in all cases, heated the solutions to the recommended temperature (a plating book that I got along with the supplies), had the voltage to the recommended values (when recommendation was between 4 & 6 volts I used either 4 or 5 volts), moved the items slightly while plating, turning them, and kept them in the plating solution no longer than the specified time. Used a platinized titanium anode and a 24K gold for the yellow, plus nickel and copper with the respective solutions.

The solutions were brand new, the thermometer was rinsed and dried between solutions, and the items being plated were rinsed in tap water and dried with clean paper towels between platings.

In short, I followed instructions to the letter, but the results were very disappointing: Copper showed through the yellow gold plating, and there were gray spots in the watch case, plus microscopic dimples spread around. Really poor quality.

I actually let the money clip stay a few seconds longer in the gold solution (could see it wasn't getting coverage), all to no avail: I didn't even get a shiny finish in it, just in a few areas it was really yellow and shiny, rest was dull and copper-ish in color, and the rhodium was really disappointing. I actually had to re-polish the case and sent it back without any rhodium plate on it.

Sorry for such a long "question", but, is it hopeless? Should I just give up altogether or is there a way to obtain satisfactory results plating? The main difficulty is that the watch cases I work with are rather high grade, and their owners are demanding as well. I imagine I can never duplicate a factory finish, but is there a way to get quality plating other than what's explained in the plating books? And I did polish and clean to perfection.

Thank you very much if you can find the time to offer me some advice.

Dario Iglesias
Dario Jewelers - San Diego, California, USA


(2004)

A. That sounds so frustrating! I am getting ready to purchase a plating set-up. Please let me know what response you received to your question. If I can help in any way or share information I learn, let me know. Take care and good luck!

Stephanie Swanson
jewelry designer - Chesterton, Indiana, USA


Plating, Brazing, Soldering & Welding

(2004)

A. Sorry for your troubles, Mr. Iglesias. Electroplating can be a difficult subject. But I think the principal cause of your particular problem was the 'wait time' between preparation and plating, and the lack of an activating acid dip. Electroplating is an electrochemical process that can only bond to a surface that is not only perfectly clean but is an 'active' metal as well. Most metals tarnish very quickly, and tarnish is a metal oxide or metal sulphide to which plating cannot bond properly.

You should clean and acid dip immediately before plating. If this is not practical, at the least you need to acid dip immediately before plating. Which acid to use depends on the substrate and the metal you are plating it with, but 10 percent sulphuric acid is often used on brass. If it's leaded brass, you also need hydrofluoric acid, which is the one material used in plating that terrifies experienced practitioners because the burns are so dangerous, and it shouldn't be used except in an industrial setting.

You can get a finish that matches the quality of a factory finish, but plating is a skill and it is difficult to learn enough merely by reading an instruction manual. Most good platers have years of experience and were trained from the get-go by other experienced platers. Try to get some hands-on help if at all possible; if not experiment on scrap. Good luck.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


April 16, 2010

A. Hi, interesting problem. I fully agree that one should not leave polished items for plating lying around for too long before plating. Immediately after preparation is vital. In my experience using the mesh anode is not always the best way, I use real platinum and a highly polished stainless steel negative when plating white gold items. Also try heating up your plating solutions before using it. Are you making up your own concoctions or are you buying them ready made? The rhodium solution I'm using only requires me to add 1 litre of distilled water per gram of rhodium solution -- let me know please. Lastly I would like to add that if there is any kind of dust or polish dirt that comes into contact with your solutions it can and will poison your rhodium bath. Hope you resolve your challenges.

Regards,

Andre Ford
- Cape Town, South Africa



Black rhodium plating problems

(2004)

Q. Dear Sir and Madam, greetings to you all.

I am a designer and a jeweler in my country. I'm very much interested in learning new techniques in manufacturing jewelry so as to upgrade and enhance my designs and finishings in the jewelry I do for my clients. I would like to learn the proper process of doing black gold Rhodium plating onto K18 white and yellow gold metal. I have tried many times to plate in black gold rhodium but the desired color does not come out to be what I have expected.The finish is not in a matte black finish like the other jewelry I see in the trade fairs and in magazines. And also I'm very much interested in learning the technique that Phillip Charriol uses to do with his cable wire watch bungles and bracelets they used in their jewelry. The finish is a very matte black finish. Thank you and hoping that your company will be able to assist me in the proper process in doing this black gold metal platings, and also in enameling finishings.

Thank you again and waiting for your reply.

Sincerely yours,

Annie C. [last name deleted for privacy by Editor]
jewelry designer - Manila, NCR, Philippines


January 30, 2008

A. You have to use a concentrated solution of black rhodium possibly of Legor that comes in 100 gms bottle and not the ready-made solutions provided by them. Also the colour will be very black I had the same problem.

Nishit [last name deleted for privacy by Editor]
solo enterprise - India


February 18, 2012

Q. Hi. I work for a family owned jeweler and recently have been having trouble pen plating black rhodium over white gold to accent black diamond pave. Our problem is that initially it plates very black, but after an hour or so, it has a brown to orangish tint to it. We have tried different plating solutions from various vendors, but with the same results. We have followed the products' directions (what little there is) as far as voltage and such, prepared the piece as carefully as possible (ultrasonic cleaning, electroclean, distilled water rinses activation bath, etc.) to no avail. This is an important step in the appearance of the pieces and it is very frustrating to not get the desired results! What can we do?
Thanks.

Andre Vanbergeijk
Bench jeweler/designer - Indianapolis, Indiana



Consumer problem of brown "slashes" on rhodium plated sterling silver

November 3, 2013

Q. I was wondering if anybody here knows of a home remedy or solution to removing brown spots or slashes out of Rhodium plated Sterling Silver. My engagement ring is made of this and it has developed these brown slashes all over, I've been taking it off when cleaning the house or dishes, and steam cleaning it only, but the slashes still appeared. Is there any way of fixing this problem without getting it re-plated? Thank You.

Stacy Levasseur
- Brockton, Massachusetts, United States


Silver Polish Cloth

November 2013

A. Hi Stacy. I'm not understanding these "brown slashes", so I'm working in the dark, and a photo would probably help. But rhodium plating is cracked, and perhaps the silver is tarnishing at the cracks. Patient use of a silver cleaner or silver polishing cloth =>
would probably help, but if the "anti-tarnish" layer of rhodium is gone, the silver will readily tarnish. If the silver is gone, the underlying ring material may corrode. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



Cloudiness problem is rhodium plating

June 12, 2014

Q. Hi, this is Ramy Asaad.
We have been getting white spotting on my pieces' surfaces; it resembles clouds. We try to clean everything, and we are make new solution but nothings helped.
We need your help if you can!
Thank you

ramy asaad
- Brooklyn, New York USA



Is Rhodium Plating dangerous

August 20, 2015

Q. I am looking to Rhodium plate custom jewelry in my apartment. I am curious about the dangers of Rhodium plating and if there are other safe alternatives out there. Ideally, I want a way to safely plate a white color (be it Rhodium or other) and a yellow color (gold or other). I have done some research on cold Rhodium plating and heard that it is safe because it doesn't emit any fumes. I was also curious if the Rhodium plating pens are safer then the Rhodium plating baths. Any suggestions and advice would be greatly appreciated.

Brandon Scott
- Wantagh, New York U.S.A



November 18, 2015

Q. Hi. We have a jewellery manufacturing company here in Dubai. We are facing a problem while plating black rhodium. After plating black rhodium on highly polished surface of gold 21k or 22k, black rhodium comes off just from rubbing by hands. Either it's a voltage problem or solution problem. I tried both ruthenium and black rhodium. Please give me any idea or suggestion regarding this problem. Thanks and regards.

Nasir Zamir
goldsmith - Dubai U.A.E


A. Hi Nasir. A highly polished surface implies the use of compounds to achieve it -- which you may not have fully removed. Have you done a simple water-break test to verify for sure that the surface is clean?

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



February 13, 2016

Q. Hello,

We are a jewellery manufacturer based in Mumbai.
We usually mostly work on gold and silver pieces, but recently started brass costume jewellery as well.

However, we have not much knowledge on how plating works on brass (we do have a plating plant with an inbuilt rectifier).
We usually do flash palladium then flash rhodium on silver pieces.

What would be the best solution for brass if we would like to give a guarantee of at least 6 month-1 year? We can use nickel as well.

We are a little confused because some people advised us to do cyanide copper, then nickel then rhodium, but other people told us that cyanide copper isn't required if nickel is there.

But I also heard that if we directly plate nickel over brass without preparing with copper, the nickel will peel off ?

We have a few pieces which are very large (it's basically costume jewellery) but they would physically fit in a 3L beaker.

There is also the idea of outsourcing the plating, but I guess if we can do it with our own equipment we could save a lot knowing that they charge by grams here.

Aakash Sharma
- Mumbai, India



Jewelry store rhodium plated my ring, but it's dull and black

March 10, 2016

Q. Has anyone ever sent their white gold ring to get a rhodium plating and the gold turned black? This happened to me at a reputable jeweler. They claim the rhodium temperature was too hot and that caused the blackness. My beautiful shiny ring now looks dull and black. they also claim they can fix this with acid. Is this true? Please help because I have my doubts. It's my anniversary ring.

Thank you,
Michele

Michele Davila
- Ossining, New York USA


March 2016

A. Hi Michele. I think I'd try a different place than the one that screwed it up :-)

It's very unlikely that any permanent damage was done, though; rhodium is very thin and shouldn't really affect the ring. Usually rhodium is removed by polishing away mechanically rather than with acid because I don't think there is any acid that can dissolve rhodium but not gold.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



sidebar2

Non-porous finish material

March 17, 2017

Q. I'm new to plating and finishing, so forgive my ignorance. I am looking to finish some very small parts that have nickel and gold elements that need absolute corrosion control in a salty brine environment. I've tried electroplating rhodium but it seems to be too porous, even at 50 micron thickness. Is there another material with similar or better corrosion resistance but is not porous? Or maybe another process would be better?

- Gary

Gary Chandler
product designer - Seattle, Washington, USA
  ^- Privately contact this inquirer -^


March 2017

A. Hi Gary. Rhodium probably isn't a good choice because it tends to be thin, cracked, and porous. Gold plating would be much better, and probably needn't be anywhere near that thick. Electroless nickel would probably be fine too, and much cheaper. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"

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