Remove rhodium plating from gold -- Is Rhodium plating reversible?

A. Hi Stela. Paul's posting was from almost 14 years ago so he probably won't answer, but diamonds are highly acid resistant. The bigger issue may be that concentrated sulfuric acid doesn't belong in homes (if that is your situation). The standard approach is probably having the rhodium mechanically abraded away by a jeweler. Any reasons suggesting against it in your case? Thanks.

Luck & Regards,

Thank you so much Ted. Yes I trust that that ( buffing ) is the way I will proceed.

Again Thank you!

A. Hi for all at topic. Rhodium is most corrosion resistant but there are a few types of corrosion:
- oxidation
- chemical
- electrolytic (best conductive metal ever)
That last one is most important because it's not giving any resistance to the current floating from anode to cathode. That means you can take off rhodium plating from any type of jewelry or even e-scrap with no touching base. Rhodium reverse electroplating process has two important steps where the first step depends from second.
1st. Electrolyte preparation to the ->
2st. Type of alloy or metal as base under the Rhodium plating.

You need know how "reactivity of metals" works one by one, which acid reacts with your base metal /alloy under Rhodium plating.
Most cases can by done by using "Stainless Steel 316" as the cathode and sodium hydroxide as electrolyte dissolved in simple tap water (rhodium takes off as yellow hydrated Rhodium hydroxide and it can changing color the olive green when *H2O is increasing). After filtration and drying in low temp. <65 °C it will be RhIV+
Second wersion can be cathode made by titanium with platinum plating as cathode and sodium chloride as electrolyte.
All types of gold jewelry is needed to be prepare in primer solution before Rhodium plating, So if have white Gold you can do a few small scratches to speed up the process.

Alkali metals react with Rhodium and there is one with can dissolve Rhodium better, faster and more efficiently then strong acidic solutions like AR.

Better to take off Rhodium as solid, flakes or mud, collect bigger ammount and dissolve it once again to make another purification and get 999.

This is only my opinion and everything what I wrote above is learned by my personal practice. So "my wife hates my know to...."

A. If your watchmaker has a formula for electro-stripping rhodium from 18K gold without harm to the gold surface I would be surprised and interested in knowing more about this formula. Maybe he can demonstrate this bit of magic on a piece of scrap gold? You are smart to be careful and I believe you will regret plating your fine gold watch.

A. Hi Bruno,

Rhodium is not generally reversed by electrical means unless it is thin and has a nickel plating underneath it. The nickel layer can be attacked and the rhodium and nickel will separate from the main substrate. You can carefully remove the rhodium mechanically using sandpaper sticks of variable grit sizes. Rhodium plating should not be reapplied unless the surface is re-polished and cleaned. All contaminants must be removed. The electroplating process does not conceal scratches or surface blemishes. Rhodium plating in pore free thicknesses of 4-6 microns combined with a proper pre-plate over the white gold will last easily 6-10 years. Rhodium plating can be made very hard and scratch resistant. Plating a watch properly is time consuming but with the proper methods, a fine watch such as yours can be restored to a pleasing and durable finish. In general avoid jewelry stores, they are nice people, but rarely have the plating processes or methods for plating in the thicknesses you will need for your watch.

Good luck!

David,

4 to 6 microns of rhodium seems unlikely from any conventional aqueous solution because of stress in the deposit. What kind of bath are you using and does the surface remain bright at this thickness?

Neil Bell
Red Sky Plating

Albuquerque, New Mexico

2001

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Hi Neil,

I meant a total of 2-4 microns total plated deposit including a preplate, of which about 1.5-2.0 microns is Rhodium. If the watch surface is a brush satin finish the rhodium can be made a little heavier. Thanks for the opportunity for clarification.

Best regards,

David Vinson
Metal Arts Specialties - Leonard, Michigan
2001

A. Hi Jodi...
There is no harm in Rhodium plating the wedding band. There will be no loss when you are plating the bands as you will be adding metal to the surface of the bands. As for removing the plating a few years later you need not bother as the plating may itself wear off showing the original color yellow.
So go ahead, enjoy the white color. Regards,

I don't agree with you cousin Prakash. I think this is a poor idea because rhodium plating is very thin and rings are very high wear items. The wedding set will not look good for long at all as the rhodium quickly wears off the bottom but only very slowly wears off the top. Don't do it.

Regards,

A. A lead anode in conc. sulfuric acid will dissolve rhodium with little effect on the gold. I use this process regularly to eradicate cracking problems in the re-melt of white golds.

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Intriguing, Paul. Are you sure you mean "anode" rather than "cathode"? Any additional details or clarifications would be great.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

A. Hi, Sandy. Hi, Lauren.

You probably won't do it chemically but, as David Vinson noted, it may be possible to polish it off. If you have skill and experience in jewelry work you might do it yourself, otherwise it sounds better to rely on a jeweler. Good luck.

Regards,

A. Hi, Vanessa. Hi, Jane.

Yes, but it's tedious because (as you will read above) it can't easily be done chemically; the jeweler has to polish away the rhodium. Good luck.

Regards,

A. Hi, Paula.

Although your question is slightly different from the ones that proceeded it, because your bracelets are silver rather than gold, it's actually the same problem: you can't chemically remove rhodium because it's as resistant or more resistant to all chemicals.

Regards,

A. Hi Joy. Yes, it's my understanding that rhodium plating probably can't be chemically removed, but it's not a good idea for me to try to remotely micro-manage a jeweler from a thousand miles away :-)

You need to tell him what you want and let him work out the details. But I think you should tell him you'd prefer that the plating be removed rather than add yet another layer. It's only millionths of an inch thick and won't affect the ring if done properly.

Regards,

A. Hi Prasanna. David Vinson says above that if there is a layer of nickel plating between the gold and the rhodium, you may be able to attack it ... and I presume that is where hot strong nitric acid would be applicable.

Paul Anderson says the rhodium can be removed cathodically in concentrated sulfuric acid, but so far nobody has commented with additional detail.

Regards,

A. Dear sir,
You just boil your jewellery in concentrated sulfuric acid until all the rhodium gets dissolved in it. Please take safety [in mind] while boiling the Rhodium plated articles.

A. Hi Ana. It's only possible to make wild guesses with such limited info. But there's car wax and then there's 'car wax', which could range all the way up to an abrasive Turtlewax rubbing compound which might be able to reduce or remove the rhodium plating on your ring. Usually it's an inexpensive thing $25-50 to get it replated.

Regards,

A. Hi Beth. "Gold coloring" or "Color gilding" is an art form that some people have spent a lifetime working on. So with zero experience in it myself, I don't want to minimize what is required for color matching ... but there are "codes" like 1N, 2N, and 4N describing the different colors. My gold plating book is out on loan, but I think you may be seeking what is called a "Hamilton gold color". Yes, it is probably possible to get your vintage band plated in a color that is more pleasing to you.

Regards,

A. Hi again. You previously said that the buildup was necessary because the ring had worn down. I am not a jeweler but I suspect s/he did not melt down and recast the whole ring, but that the build up was done with some sort of silver solder which is a different color than the gold of your ring and must be plated.

Only if the metal you want removed is a different metal than the metal which you want to retain, can chemical stripping be an answer: stripping chemicals cannot read minds and remove only what you don't want and leave in place all of what you do want :-)

But it may be possible to mechanically abrade (polish away) what you don't want. Again, short of melting and recasting the entire ring though, there was probably no way to build it up without changing the color such that replating was a necessary part of the repair process. So it's not a matter of avoiding plating, it's a matter of plating it in the color which you prefer.

Regards,

A. Hi Muriel. Probably not. A ring which looks like white gold is most likely made of solid white gold.

Regards,

Hello Chi Chi. When you buy a 'white gold' ring, the gold underneath the rhodium plating is supposed to be a tolerable shade of white so the contrast is not ugly as the plating wears away. However, sure, it's possible that the ring is actually yellow gold. But it's complicated: maybe the ring is white gold and the prongs are yellow; or it's yellow but a silver solder was used on the prongs.

You could have a good jeweler polish away the plating and see what you've got (hopefully a nice yellow gold throughout), but unfortunately I doubt that a reader can confidently predict what will be found under the plating.

Regards,

Recycling rhodium plated brass earrings

A. Hi Patricia. E-coatings are organic (paint) and most can be removed with solvents of some sort. Most platings can be stripped from most substrates with a chemical or electrochemical process, but unfortunately rhodium plating is not usually one of them. Sometimes the rhodium plating has nickel plating underneath it, and in that case it may be possible to get to the nickel layer and dissolve it, undercutting the rhodium, especially when it's only 1/20 of a micron thick. The details matter.

If the shape of the parts is simple enough, it is possible to polish off the rhodium, but if you can't practically reach it, you can't.

Sorry, I don't know enough about brass smelting to fully understand what the problems are with contamination from the plating layer, or how a smelter can remove that contamination. But I think the main issue here may be that brass is probably always recyclable, but may not necessarily always be easily & simply recastable by a home-based hobbyist. Good luck.

Regards,