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Letter 14022
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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 of 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
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.
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Venkat Raja |
Thanks David and Venkat. The gold on today's watches is pretty thin. I realized the plating was thicker on older watches, and sort of expected the 3 microns that Venkat talks of. But I never realized it could be 20 microns or more.
Regards,
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 Ted Mooney finishing.com Brick, New Jersey |
Hello, my name is Paul. I'm a student of Edinboro University of Pennsylvania Art Program. I do some gold, silver and copper plating. Some time 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 couple rectifiers in 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 plate. I don't want to use sodium cyanide, to 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
you can use caustic soda its a drain cleaner - available at most
leading stores.
I used it on a old watch, it takes about 3 hours..to remove all the
gold plate.
thank you good luck
Cawnus Smith
- Detroit, Michigan
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Ed. note: Cawnus is apparently talking about using caustic soda to
electrolytically strip gold, not as a simple immersion process, as
only aqua regia dissolves gold.
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
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.
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Ted Mooney finishing.com Brick, New Jersey |
1000 ml H2SO4 in 2000 ml Pyrex casserole
dish with appx. 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 charger [link is to product info at Amazon] 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
Hi I just read your letter and can you go in to 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
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
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November 28, 2008 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
January 11, 2009 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
October 2, 2009 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
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