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Gold plating removal

Q. How (what chemical) can I use to remove the gold plating from an old watch?

Thomas Tomcik
- Burlington, Vermont


A. Hi, Thomas. Since you don't say what the watch case is made of, or what kind of finish you want to apply to it, I'm guessing you are trying to salvage the gold value of the watch?

The weight of gold per square foot for each millionth of an inch of thickness is .00147 troy ounces. If the watch is from the last couple of decades the gold is probably about 20 millionths of an inch thick (about half a micron): that's .0294 troy ounces per square foot. If the gold plated area is 2 square inches, it's .00041 troy ounces of gold. It's about 25 cents worth of gold for a relatively recent watch. But if it's a really old pocket watch, the plating is a hundred times thicker and it could easily contain a substantial amount of gold. Please clarify what you are trying to do. Thanks!

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


A. Hi Tom,

I am going to assume that you are seeking a way to remove the gold from the watch for refinishing purposes not for salvage of the gold. First of all many old watches had good thick plated coatings for longevity. If you are seeking to chemically strip the gold off the watch, it is difficult to do without attacking the threaded and fine mechanical portions of the watch (thin flash plated areas). If there is severe "brassing" (exposed base metal, i.e., brass or nickel, on the wear edges), the stripping chemistry even with buffers will attack the brass severely, long before the thick gold plating has been removed chemically. Chemical stripping is fine for gold coatings 2 microns or less, but you will still have the disposal burden to contend with.

Mechanical removal is the safest using small files and paper sticks. In many cases it is faster than chemical stripping, especially on old pocket watches with 20 microns or more of gold. The filings and "sweeps" can be sent to a refiner for reclaim of the gold. If you do a large quantity of watch refinishing it is worth it.

Hope this helps, Good Luck.

David Vinson
Metal Arts Specialties

Leonard, Michigan



 

A. Mr.Tomcik,

First check out what is the base material. If the base is brass and under coated with Nickel you can strip using Sulphuric acid/glycerol based stripper, or sulphuric acid/copper sulphate based stripper. If the base is SS you can strip it with sodium cyanide solution. If a electroplated watch whose effective surface area is between 0.10 to 0.15 sq.dm is plated for 3.0 to 3.5 micron it will have approximately 40 to 80 milligrams of gold.

Venkat Raja
- Kitchener, Ontario, Canada

Refining Precious Metal Wastes


Recovering Precious Metals


Recovery And Refining Of Precious Metals



++++++

Q. Hello, my name is Paul. I'm a student of Edinboro University of Pennsylvania Art Program. I do some gold, silver and copper plating. Sometimes I need to recover the gold plated on the "hoops" pieces. I need to know what chemicals I can use with rectifier type gold plate recovery system. We have a couple rectifiers at our disposal: one that is 10 Volt 80 Amp second is 4 Volts 5-30 Amp, and the third is 6 Volt 10 Amp. This is used for copper plating. I don't want to use sodium cyanide -- too dangerous. Is the any other chemical that I can use for the solution to strip gold from copper and stainless steel? What rectifier will perform the best to strip gold from other metals? The left out metal materials are going to be properly disposed, and only gold recovered and kept. Any help will be appreciated. Paul.

Paul Pri
Hobby, Student - Erie, Pennsylvania


March 3, 2008

Q. Can anyone help? I have a pretty rare military cap badge that someone has gold plated for display! The base metal is bronze and my local jeweler tells me that if he tries to un-gold plate it electrically in an acid solution, it will eat the bronze away and ruin his £200 solution and my badge. I have tried to gently rub it off but it's impossible ... any suggestions?

Howard Smith
- Cardiff, Wales, G. Britain


March 4, 2008

A. Hi, Howard. Please carefully reread David Vinson's reply -- I think it's what you are looking for. You need to find a shop who will mechanically polish the gold off. Good luck.

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

April 10, 2008

A. 1000 ml H2SO4 in 2000 ml Pyrex casserole dish with approx. 1/4 teaspoon of glycerine well mixed into the H2SO4. Submerge a lead bar or rod in the dish with enough of the metal sticking out to connect the negative (-) lead. Obtain a variable power supply (10 AMPS MAX) @6-12 volts -- a battery chargeramazoninfo works great!). Connect the negative lead to the lead electrode. Connect the positive (+) lead to a cable with STAINLESS STEEL ALLIGATOR CLIP. Attach the item you want stripped to the clip, turn on power supply and lower the piece you want stripped into the acid/glycerol solution. PRESTO--CHANGO! The black residue is approx. 95%+ pure gold. You will need to dissolve and purify product with Aqua Regia or HCl and regular Clorox Bleach (halide leaching). This is simple, safer than HNO3 fumes. I have been using this for years with great success. Good Luck!

Les M. Barnes, LAC
- Carolina Beach, North Carolina


August 23, 2008

Q. Hi I just read your letter and can you go into more detail and explain the chemicals you are talking about on the halide leaching , bleach, etc. , I have the black mud and need to get back to gold. Thanks Mike

Mike Giannio
- Millville, New Jersey


September 15, 2008appended

Q. Hello

I've got a gold plated i.d. bracelet that I've had for twenty years. Half of the gold plating on the bracelet has worn to leave it silver and gold. What can I use to remove all the gold to turn it completely to silver?
thanks
ronnie

Ronnie Judd
- Christchurch, New Zealand


November 28, 2008

Q. I have about 20 pounds of 1/4 inch x 1 inch 360 brass rods that are gold plated. How do I recover the gold?

John Urspruch
Musical instrument repair tech. - Brick, New Jersey


January 11, 2009

A. You can it resolve in AR and recover it with sodium disulfate that is known as recovery chemicals and wash it with DI water

David Babu
- Kerala, India


May 2014

Hi. While David is no doubt correct, the question for me is whether dissolving everything will be practical in an individual case. I don't know how you can decide until you know what you've got: purity of gold plating, thickness of plating, weight of brass compared to weight of gold, etc.

Regards,

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

October 2, 2009

Q. I have some aluminum chain that is gold plated and I would like to remove the plating. Can it be done without damaging the chain and what should I use?

Alexander Gray
- Bedford, Ohio


March 7, 2010

Q. I have 8 sets of 24k gold plated silverware and would like to remove and recover the gold but I need it step by step so I don't bugger any of it up.

Pookie Bazemore
- Norman, Oklahoma


March 2010

A. Hi, Alexander; hi, Pookie. There are things that a competent person can learn how to do from written instructions, like painting a wall or baking a pre-mixed cake. And there are things that a person won't learn to do from step by step instructions, but only from practice with supervision, like rebounding a basketball well or piloting a jetliner. You can search the internet forever but you will never find step-by-step instructions for those things.

As you are discovering on this page, people do tell you that mechanically polishing the gold off may be a better way to go than trying to dissolve it, but they can't give step-by-step instructions for recovering the gold and not damaging the chain or flatware because it's an acquired skill. You can take it to a plating shop for removal of the gold, but almost surely this will cost money, not pay money, because the value of the gold is minimal compared to the effort in removing it. Good luck.

Regards,

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

January 4, 2011

Q. How can a person recover the gold from 22 ct. plated stamps?

Rocky Hollingsworth
Hobbyist - Coos Bay, Oregon USA

August 3, 2011

Q. Hello there!
I have just done my first gold plating, a large bracelet, brass 15.5 x 6.5 cm, plated with 18k ready made mixture. I used a magnetic mixer and rectifier, my problem is the color came out not nice and I want to strip it and redo the piece. I was reading the thread but got more questions: the sulfuric acid/glycol mixture suggested by Les Barnes seem easy enough, I want to know: do I have to heat up the mixture if so, what's will be the temperature? Can I use the titanium sheet instead of the lead rod. Please explain as I have no clue as to what I am doing.

Ellie Stocco
- Hong Kong

August 18, 2011

Q. I have about 25 pound of aluminum 'parts' that are electroplated in gold. I understand that this gold (although pure) is probably VERY thin (microns). Is there any significant value in stripping and collecting this material through a precious metals vendor? I would REALLY appreciate and answer, thanks for all the good work you do on this site.

Jeff Constantine
scrap dealer - Mission Viejo, California

August 19, 2011

A. Thanks, Jeff.

You are right that it is likely that the gold is very thin. I would saw one of the items in half and try to estimate the thickness of the gold with a jeweler's loupe or a microscope. Until you have some idea of the thickness, it's impossible to estimate the amount of gold that is there. Once you do know the thickness, it's relatively easy. If it's thousands of dollars worth of gold, it's worth it despite the difficulties. If it's $35 worth of gold (and it might be a lot less), it's not going to be worth the cost of recovery.

Regards,

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

October 5, 2011

Q. How do I strip the gold off the Indy Car where I can sell it, I bought the indy car about 15 years ago it is of the 1998 GRAND PRIX OF Houston

Robert Acevedo
I am a home owner - Angleton, texas US

October 6, 2011

A. Hi, Robert.

These cars are, as you know, collectibles. I think you'll get far more from selling it as is than from stripping it. But if you insist, then start by cutting the car in half and estimating the gold thickness with a microscope. You'll want to know how much gold is there (I suspect it's not much). I've heard of people scraping the gold off the contact fingers of printed circuit boards, and that may be the best way for you to get the gold off. Good luck.

Regards,

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

January 26, 2012

Q. Retired vet needs some answers. I would like to know if I can take and process it all back to gold. Is it diff. from the rest of this thing I have been buying this stuff for years.

Mike Anderson
looking to help keep the earth - Des Moines, Iowa

September 17, 2012

Q. HI ALL. I HAVE A STAINLESS ROPE CHAIN THAT IS GOLD PLATED (SO I ASSUME THAT THIS IS A VERY THIN LAYER) AND I WOULD LIKE TO BRING IT BACK TO SHINY STAINLESS. COULD I JUST CLEAN IT VIGOROUSLY WITH SILVO (OR THE LIKE) TO ACHIEVE THIS, OR WOULD IT NEED MORE SPECIALISED ATTENTION? REGARDS, TODD.

TODD RYAN
- CAIRNS, QUEENSLAND, AUSTRALIA


December 10, 2012

Q. Indian woman wearing glass bangles. The glass bangles have some gold spots. I want help for an easy procedure which I can do in home to easily remove and collect that gold .

sham shinde
- Navi-mumbai,Maharashtra, India


December 11, 2012

A. Hi Sham. Do you have any reason to suspect that these gold spots contain significant gold value? Usually gold plating is thinner than a micron; sometimes much thinner. You might find 25 cents worth of gold or less, after investing a lot of time, and spending much more money that that for recovery tools and chemicals.

Gold recovery is serious business, so the first step is determining how much gold is there. Good luck.

Regards,

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

January 17, 2013

Q. Hi, I have been trying to refurbish an antique/vintage bracelet. I believe it was once gold plated. There are parts of the back side that are gold color. The worn areas are various colors of copper, silver, and a dark grey pewter type metal. I'm not sure if base metal at this point, but as I took tarnish remover to part of it, it looked like copper. However, in the really worn areas the copper is worn away and a dark grey metal is showing. It's a very detailed piece of jewelry and I love it. Wanting to save the base metal and as much detail work as possible. Do you have any idea what the base metal could be? If it is nickel or pewter, will it need a protective coating of something to keep the design safe? So far I have gently tumbled it in a jewelry tumbler which removed the tarnish/oxidization but not plating. I've used extra fine polishing bits on my Dremel and removed some of the copper layer, very tedious work and it is taking a layer of the design. Any other way to remove without chemicals?
Thanks for you, in advance, for all the info!

Lesa Craig
- Pflugerville, Texas, USA


February 24, 2013

Q. I have 50 George Catlin commemoration coins.They are 24Kt electroplated over bronze. Are they worth trying to take gold off?

Don Johnson
- Nashville, Tennessee USA


February 24, 2013

A. Hi Don. Looking at similar coins on E-bay, they are not gold plated, and are listed for $12-$15 each. If yours are gold plated, I see no way of knowing, without testing, how thick the gold is . . . but I doubt that it's more than 20 or 30 millionths of an inch (you would have lost the engraving if the gold were thick). So do a calculation. Personally, I'd try to sell them on E-bay or Craigslist rather than destroying collectibles. I'd suggest the same for your Rolex if you have one :-)

Regards,

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

July 18, 2013

Q. Hi. I've found this blog the most informative in compare to others.
Here is my question. I have a old Omega from 1940's.
The back says "PLAQUE OR L 80 MICRONS".
Can this be called solid gold? And what would the carats be? Thanks

Rumpelstiltskin Asecas
- Los Angeles California


November 2013

A. Hi Rumpelstiltskin. I think that engraving is in French and is saying "Plated with gold 80 microns thick". So, no, it's not solid gold; rather, it has a plating a little over 3 thousandths of an inch thick -- which is quite thick for gold plating.

Regards,

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

October 31, 2013

Q. Please, sir help me for recover the gold from glass bangles.
Because I have much scrapped bangles.

Sham B. Shinde
- Mumbai, Maharashtra, India


November 4, 2013

A. Hi Sham. As we've said repeatedly, recovery of gold is serious business, and step 1 is determining how thick the gold plating is. This is absolutely essential, not just to know whether the effort is worthwhile, but to track the gold content through each subsequent step so the appropriate amount of chemicals can be added.

Anyone who skips this step is not just being foolish, but is only playing, and playing with very hazardous chemicals to boot. So, please start by telling us how thick the gold plating is. Thanks!

Regards,

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


April 22, 2014

Q. I restore classic autos, and in the process of acquiring original stainless or chromed trim pieces, I have come across many that have been gold plated. This is not a desirable thing to a restorer. As an example: a chrome plated wire wheel with stainless steel spokes that the spokes have been gold plated. Is there a way to remove the gold plating from the spokes without damaging the chrome finish on the rest of the wheel? I am not interested in recovering the gold, just salvaging the classic car part. Thanks Fred

Fred Kelly
- Deland, Florida USA


April 24, 2014

Q. How can I remove the gold plating trim on the bathroom faucet? The finish beneath the plating, which appears where the plated trim has worn down, appears to match the same brushed nickel as the rest of the faucet.

Harvey Weiner
- Dallas, Texas, USA


April 30, 2014

A. You have run into the problem of dissolving a highly chemical resistant coating (gold) without attacking the much less resistant substrate, usually nickel.
Gold stripping involves chemicals like cyanide and is certainly not suitable for amateurs.
Your best bet would be to take advantage of the fact that gold is much softer than whatever is underneath and easily wears away -- which is one reason that it is a very poor finish for bathroom or motorbike fittings. It is also very expensive so you can be certain that it will be thin!
Try a brass brush on a Dremel type hand tool.

Geoff Smith
Hampshire, England

Dremel Kit



Recovering gold from the one-micron plating on glass bangles

May 17, 2014

Q. Repeat question: ask you sir, these glass bangle having nearly 1 micron layer. AR procedure I did, but I am not successful. Help me for proper procedure.

sham shinde
- Mumbai, Maharashtra , INDIA


May 22, 2014

A. When using aqua regia (AR) to dissolve gold, most of the literature says to pre-mix it in the ratio of 3 or 4 parts hydrochloric acid (HCl) and 1 part nitric acid (NHO3). This will certainly dissolve the gold but, when attempting to precipitate the gold with a reducing agent, such as sodium metabisulfite, sodium sulfite, etc., you will find that the gold will not drop out. The usual reason for this is that some free nitric acid still exists in the solution. The gold won't precipitate until all the nitric is removed. The traditional method for removing the free nitric acid is to evaporate the solution to a syrup, add a few ml of HCl and evaporate further. This is repeated 3 or 4 times or, until all the nitric has been driven off. However, this is a time consuming cumbersome method.

A much better method is to not premix the 2 acids. The trick is to add the acids separately and only use enough nitric to dissolve the gold - no more, no less. Any combination of HCl and HNO3 will dissolve gold, even in a 100/1 or 1/100 ratio. An excess of HCl will not hinder the precipitation but any excess of nitric can cause problems.

Here's how I would do it.

(1) Put the material in a large beaker and barely cover it with HCl, only. To avoid the possibility of a foam-over, the material should not occupy more than 1/3-1/2 of the beaker capacity.
(2) Heat the HCl to about 65 °C on a hotplate. In case of a mishap or beaker breakage, it is best to first place the beaker in a ceramic dish that is made to withstand direct heat. The only one I know of that will do this without breaking is a Corning Ware "StoveTop" dish.
(3) Add a few ml of HNO3. You will observe gassing and the gold will start dissolving.
(4) When the reaction subsides, give the solution a gentle stir and add a few more ml of HNO3.
(5) Repeat until all the gold is dissolved. Stop adding nitric.
(6) Allow to cool and pour off the solution into another beaker. Rinse the material well, using as little water as possible. Save the rinses and keep them separate from the main solution.
(6a) If the only metal being dissolved is gold, there is probably a lot of life left in the solution. You could probably use this same solution to process more material. If you do this, follow the same procedure above.
(7) Combine the solution(s) and rinses. Add enough extra water so you end up with a total volume that is about 4 times the volume of HCl that you started with.
(8) Filter the solution until it is crystal clear.
(9) Precipitate the gold with the precipitant of your choice. I usually use sodium sulfite. About 2 grams will precipitate 1 gram of gold. I prefer to dissolve it in a small amount of hot water before adding it to the solution. If there is no excess nitric, the brown gold powder will start dropping immediately. If there is a little excess nitric present, the precipitant will first react with the excess nitric before the gold starts dropping. To make sure all the gold has dropped out, the solution can be tested by adding a drop to a spot plate (or white plastic spoon) and then adding a drop of stannous chloride solution (1 gram dissolved in about 20 ml of a 50/50 HCl solution diluted with water). A purple or black color indicates that there is still gold present in the solution. In that case, more precipitant is needed.
(10) Filter the gold powder, rinse it well with hot water, dry it, and melt it.

Notes:
(1) This process generates lots of noxious, toxic fumes and a fume hood is a must. Work with good rubber gloves and a plastic full-face shield.
(2) To get an idea of the acids needed, 1 troy ounce of gold requires about 125ml of HCl and 25-30 ml of nitric.
(3) Instead of using aqua regia, this gold plating can be dissolved in a combination of HCl/hydrogen peroxide (H2O2) or HCl/chlorine laundry bleach (sodium hypochlorite - NaClO). As with nitric acid, the H2O2 or NaClO should be used in small quantities. Before adding the precipitant, any excess of these can be removed by simply heating the solution for 2 or 3 hours. Get it quite hot but don't boil.

Chris Owen
- Nevada, Missouri, USA


May 2014

thumbsup2Wow. Chris knows his stuff!

Regards,

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


June 2, 2014

Q. A store has a necklace for sale composed of twenty coins connected by metal loops soldered from one to the next. They are flying eagle pennies from 1857 and 1858. Depending on condition, they could be worth anywhere between $30-$100 each. The thing that makes them worth next to nothing, is that someone plated the thing with gold. Those coins are 88% copper and 12% zinc^nickel. Is there a way to get that gold off so they could be viable collector coins again? If there is, then it makes a sound investment. If not, it's just a curiosity made by someone who had no clue on what they were destroying. Thanks in advance. Ray

Raymond Harris
- Gainesville, Florida, USA


June 2, 2014

Oops I just posted a question regarding the removal of gold plating from United States Flying Eagle pennies, the first small cents, officially stamped for general circulation in 1857 and 1858. I wanted to see if it could be done, NOT to recover the gold, but to bring the pennies back to a state where they'd have some collector value. However I gave the wrong base metals. They are composed of 88% copper and 12% NICKEL, not zinc like I stated. If the acid eats into either metal, then it's not worthy of pursuit. Sorry for the error.

Ray

Raymond Harris [returning]
- Gainesville, Florida, USA


June 5, 2014

A. Besides the gold, there is likely to be a nickel plated layer between the gold and copper. Both would have to be removed, probably using different solutions. Also, it is very possible that the solder has damaged the coin. Even if it hasn't, the solder must also be removed in a separate operation.

To remove these 3 things (gold, nickel, solder) would require some experimentation and the only thing you have to experiment with are the coins themselves.

In my opinion, it is unlikely that the coins could be successfully restored to their original condition.

Chris Owen
- Nevada, Missouri, USA


June 5, 2014

Q. I had some Flying Eagles back when I was a kid, and as I remember there was no cladding between the copper and nickel. The coins had a solid grayish tinge, so I always thought the planchets they were stamped from were poured as an alloy. Or are you suggesting that they might have been dipped in nickel for the gold to adhere better to the coin?

I took a close look at them yesterday, and a handful were in the extra fine category while the bulk were very good to fine. That means this was done long ago when they had no numismatic value, and I suspect the plating is thicker than what you get today. If true they would have to be dipped longer. More problems.

As far as the solder goes, I thought I'd be able to shave it off the edges. They're smooth, like today's pennies, and there's no overlap slop on either the obverse or reverse sides of the coins. Someone was very careful.

A jeweler suggested polishing off the gold, but that's a big no, no, in the coin world, and would cut values in half.

Pondering all this is foolish to a degree, but if my curiosity, and hopes for a potential profit had not been stoked, I wouldn't have learned so much about the world of finishing. Chemistry was not my strong suit, but I confess I've learned a bit about a subject that had never crossed my mind until a few weeks ago. Learning is always a good thing.

Ray

Ray Harris [returning]
- Gainesville, florida, USA


June 5, 2014

Well, upon further research due to the response to my post, I learned about a Nickel wash preventing copper from intermingling with gold plate and things like "skin effect resistance". It looks like there's no way to bring those great old coins back. I'm glad and sad that they were all from 1857 and 1858. If they were some of the 2,000 presentation coins from 1856, they'd be ruined coins normally worth six to ten thousand each! So tantalizingly close and yet so far.
Thanks. This wandering has been an education.

Ray

Ray Harris [returning]
- Gainesville, Florida, USA

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