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Formulas for brush plating solutions for gold plating

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Q. Greetings:

I was wondering where I might recipes for copper, gold and silver (non-cyanide) electrolytic brush plating baths. I understand several manufacturers market some of these with all sorts of proprietary additives for sale but I am just looking for basic content information for experimental purposes.

Thank you.

J. Pankow
chemist - Denver, Colorado, USA


+++

A. Hi J. The Metal Finishing Guidebook or the Electroplating Engineering Handbook would be good starting sources for 'recipes' for plating solutions. Brush plating solutions are usually more concentrated, closer to a gel, than bath plating solutions. But a quick word of warning for others who may be reading this is that electroplating is about process sequences not recipes. A rule of thumb is that 90% of the effort is in pretreatment, and 90% of all plating problems are pretreatment issues. If the substrate is properly prepared, it will plate well; if it isn't prepared well, efforts towards plating it will usually be wasted.

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


 appended

Q. Dear Sir:

I allow myself to write to request you technical information (recipes) for the preparation of electrochemical solutions (especially those based in Nickel and chromium) for process of Brush Plating specially dedicated to the diameter resizing in axes and holes of steel pieces and other ferrous alloys. This information doesn't exist in my country, for this reason , I request it to you humbly. I have knowledge these solutions are of high concentration and they are quite different to the solutions used in the classic electrochemical processes.

Sincerely,

CAMILO ALFARO
- Lima, Peru

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Camilo:

You have to be kidding. You are asking for other persons or companies to disclose trade secrets that make them profitable and give them to you (a potential competitor), for free? Conventional electroplating has been around for very long time and the formulas are public domain. Not so brush plating.

Guillermo Marrufo
Monterrey, NL, Mexico


Guillermo,

Obviously , I don't request recipes with registered marks. I only want to know recipes-formulates of general use . They won't be as efficient as those of registered mark but they can also be useful.

Regards,

CAMILO ALFARO
- Lima, Peru


 

A. The only place that I have seen home brew formulas readily available, was several years ago in the Metal Finishing Guidebook. The article was by an engineer at Boeing. Check with Metal Finishing to see if you can get a copy.

James Watts
- Navarre, Florida

misc. plating stuff
For Sale cheap




+++appended

Q. Is there a simple formula I can follow to make my own gold which I will be using to gold plate emblems on cars electronically? Any help would be appreciated.

Best Regards,

Frank J Rios
- Dallas, Texas


+++

A. Hi, Frank. It's fairly complicated, and brush plating solutions must be concentrated and probably have thixotropic agents added for thickening.

Even if you know the formulas, it might not make sense anyway. Gold is so expensive that the tack-on costs of proprietary chemistry are usually a fairly minor mark-up, so I don't know of any professional platers or jewellers who will risk losing very expensive gold to poor plating to try to save a little bit on the carrier chemicals.

The thing in your favor, though, is that car emblems are the easiest thing in the world to plate -- because all you are doing is stripping a few millionths of an inch of chrome from an item that was polished, pretreated, and beautifully nickel plated by an OEM, and replacing that chrome with a few millionths of an inch of gold. Prep is at least 90% of the work in plating, and none is required in the case of gold plating nickel-chrome emblems :-)

Good luck,

How to Make Gold Plating
Solutions (DVD)

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Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


+++

A. Ferrocyanide gold bath (late 19th century):
2,65 gm gold chloride
15 gm potassium ferrocyanide
15 gm sodium carbonate
1 lit water
Stainless steel anode, 2-6 V / 0,5 A/dm2
In boiling water dissolve ferrocyanide; when dissolved, add carbonate; when it is dissolved add gold chloride and boil it a minimum of 30 minutes.
Must be filtered (cold) and then you can use it. Never mix it with acids!
Only grease and oxide free objects can be plated!

Goran Budija
- Zagreb, Croatia


August 22, 2010

Q. Thanks for the formula but would you please clarify some values.
2,65 gm gold chloride. Is this 2.65 gms?

Stainless steel anode,2-6 V/o,5 A/dm2.
What is "V/o"?
What is "A/dm2"?

Thanks in advance, Alan.

Alan Symbol
- NSW, Australia


August 23, 2010

A. Hi, Alan

Europeans sometimes use commas as a decimal point where people from the USA and Australia would expect a period. So, yes, 2,65 is 2.65 and the electrical requirement is 2 to 6 volts at a current density of 0.5 Amps per square decimeter.

Note that this formula involves dangerous cyanides.

Luck and regards,

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Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


August 25, 2010

Q. Thanks Ted, I thought that was the case. Goran's "recipe", is that for brush or bath plating? I am hoping both. Thanks in advance.

Alan Symbol
- NSW, Australia.

August 26, 2010

A. Hi, Alan.

Goran is a metals conservator at a museum and, as you can see, he is a tremendous resource for historical metal finishing issues. But unless you are trying to replicate something from the 1800's, I personally don't think it makes sense to forego 120 years of progress and use a plating formula from Thomas Edison's early days, probably decades before anyone even thought of brush plating. I suggest, again, purchasing a modern gold plating solution that will deliver a proper deposit, rather than having to spend five or ten times as much applying a plating that needs to be five times as thick in order to deliver a pinhole-free coating :-)

But if you are going to mix up your own chemistry, I hope you are a chemist fully aware of the dangers of cyanide. Professionals never attempt to mix their own gold plating solutions as far as I know; the only people who do so are PhD students trying to fully understand the influence of all variables. Best of luck.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

Clean Earth Cyanide-free Gold Plating Solution



May 8, 2012appended

Q. Dear all,
From the advice, I tried to purchase gold solution but it's hard to get from my city. I graduated from chemistry faculty so I'd like to make gold brush plating solution. From letters on this forum, I can make GPC but I don't know exactly the additive agent such as: brightener, hardener ... Please help me if you can. One more question, I wonder why the gold solution I saw on the internet is pink instead of yellow color of GPC. I guess it include mono dispersion of nano gold particles, is it true?

Thank you in advance,

Nice regards,

anh_nguyen_the

Anh Nguyen The
- Hanoi, Vietnam


November 21, 2012

A. Hi, Anh.

The brightener/hardener for gold plating is sometimes a metal salt such as cobalt rather than an organic material.

I am not familiar with the specific pink solutions you speak of. I suppose it's possible that some gold solutions have nano particles of gold, but in the general case, the gold must be dissolved as a salt, not be present as a particle, and I understand that small amounts of copper steer the color towards pink. Good luck.

Regards,

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



July 28, 2013

Q. Dear Sir:

I need additional info. on the answer (Ferrocyanide gold bath (late 19th century): It states 2.65 gm gold chloride, 15 gm potassium ferrocyanide, 15 gm sodium carbonate, 1 liter of water, stainless steel anode. You also state: In boiling water dissolve ferrocyanide; when dissolved add carbon carbonate; when it is dissolved add gold chloride and boil for a minimum of 30 minutes.

What I really need to know is what, when (in the process) the kind of brightener to add to this solution and what when (in the process) the kind of cobalt hardener to add to to his solution. Please give this to me again with the included answers.

Thank You

Doyle Whitaker
- Brooklyn, New York, USA
  ^- Privately contact this inquirer -^


July 2013

A. Hi Doug. Please tell us what you are trying to do and why, because we are mixing apples and oranges in a confusing way, and I have no idea what we're even talking about :-)

Cobalt additives and organic brighteners were certainly not used in 19th century gold plating formulas. Thanks.

Regards,

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Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


August 2, 2013

Q. Hello Ted: It is my understanding that the formula I originally quoted, can be used to Gold plate an object.
It is also my understanding that adding a brightener to this solution (self explanatory) and adding cobalt to this solution will help produce a finish which is termed hard gold. Is this true or false? Thank You.

Doyle Whitaker
- Brooklyn, New York USA


August 2, 2013

A. Hi Doyle. It's more false than true.

Sorry for the communication difficulty, but when I asked you to please tell us what you are trying to do and why, I didn't mean what two or three chemicals are you trying to mix . . . I meant why are you trying to formulate a gold plating process, particularly one from the 1800s, what do you hope to plate with it (jewelry, electronic contact tabs, etc.), and to what end?

You are clearly welcome to try to formulate a plating bath yourself, but in case you don't know, people generally buy gold plating processes rather than formulate them because a thin non-porous layer from a proprietary bath costs less and performs better than a thicker layer from home-brew, plus you get the benefit of the supplier's knowledge. In my own career of 40+ years in the industry, I don't recall a single plating shop that made their own gold plating solution from commodity chemicals (although some held as trade secret their manipulations to get certain properties like specific color).

Let's start with a table from Gold Plating Technology: =>

gold plating technology

Gold Plating Technology

You are trying to start with a 19th century ferrocyanide "color gold", and trying to add cobalt and/or an organic brightener like EDTA to it as if it were an acid hard gold plating solution. I don't think there is much chance for success. For one thing, you must be well into the acid range to get the cobalt to deposit. Further, quoting D.G. Foulke, in Goldie again, "The preparation of gold baths using potassium ferrocycanide goes back some 150 years, when alkali cyanides were impure and expensive while potassium ferrocyanide was fairly pure and cheap". The overall thrust of his comments is that the ferrocyanide itself has been found to not actually be a part of the process, and it's silly to use ferrocycanide now that we know better.

If you are looking for a "hard gold", this would be the "Acid" gold in Goldie's chart, with a simple cobalt salt added so it co-deposits as an alloy of perhaps 0.5% cobalt (although I understand that it's often premixed into the gold solution), and perhaps EDTA as an organic additive. So the direct answer to your question of when they are added is: not in the initial compounding, but after the initial compounding is done. Good luck.

Regards,

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


August 14, 2013

Q. Hi Ted:

A Mr. Gordan Budija suggested the following formula for a gold bath.

Ferrocyanide gold bath (late 19th century):
2,65 gm gold chloride
15 gm potassium ferrocyanide
15 gm sodium carbonate
1 lit water
Stainless steel anode, 2-6 V / 0,5 A/dm2
In boiling water dissolve ferrocyanide; when dissolved, add carbonate; when it is dissolved add gold chloride and boil it a minimum of 30 minutes.
Must be filtered (cold) and then you can use it. Never mix it with acids!
Only grease and oxide free objects can be plated!


Can this solution be used to plate a brass object? Is this to be used in the normal electrolysis process or is this to be used in the brush-on method?

Doyle Whitaker
- Brooklyn, New York, USA


August 15, 2013

A. Hi Doyle. Further up the page I remarked that I didn't think anyone had heard of brush electroplating in the 1800's -- so I presume the formulation is for normal tank plating. I know of no reason why brass cannot be the substrate to be plated with this solution if we make the leap of faith that it works at all :-)

But I'll ask for the third time what you're trying to do -- because it is not our intention to lead you down dead ends, or toward dangerous chemistry, or obsolete processes, while leaving out important things you should be told . . . but there's no way we can even guess what you're trying to do or why, and therefore what we should be trying to advise you about. But best of luck.

Regards,

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


August 16, 2013

Q. Hello again Ted:

All I am simply trying to do is gold plate a few brass pendants. Will this process work?

Doyle Whitaker
- Brooklyn, New York, USA


August 2013

A. Hi. I have no experience with this 150 year old process, but Goran is a metals conservator who feels it will deposit gold, and I have no reason to think it won't. I'm still wondering why you're trying to do this rather than using a modern plating solution, but best of luck with it.

Regards,

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


August 20, 2013

A. This type of bath is very stable, relatively simple to prepare, without any free cyanide, and you can use it to gold plate brass (or any other copper alloy), silver, iron and pewter (according to J.Fischer, D.E.Weimer, Precious Metal Platingamazoninfo, Teddington 1964, p.115). That type of bath is oldest cyanide-free gold plating process: 1841! (according to other sources thiosulphate bath). According to some sources still in use in Russia (Halilov, I.H. Galvanotehnika Dlya Yuvelirov,plating Handbook for Jewelers, Saratov 2003, p.38).

Hope it helps and good luck!

Goran Budija
- Zagreb, Croatia


August 22, 2013

Dear Mr. Goran Budija:

Thank you for your response to my question. I have a few additional questions I would like to ask you also before I get underway.

(1) You state: This type of bath is very stable, relatively simple to prepare, without any free cyanide ... I want to clarify this one point. Since you are mixing Potassium Ferrocyanide with boiling water and this already contains cyanide, wouldn't this be a dangerous thing to do?

(2) If the pendants I plan to plate are approx. 1 inch square, how many pendants of this size would you estimate this solution will plate?

(3) What is the gold karat value of this solution? Would it be equivalent to 10kt, 12kt, 14kt, 18kt, or 24kt.

(4) Can this solution be used in the both the electrolysis
and the brush on process?

(5) When gold plating with this solution, is it necessary to wear protective equipment like face mask, gloves, aprons, booths etc.

Hello Ted:
The last time you responded to one of my inquires you wrote: "... I'm still wondering why you're trying to do this rather than using a modern plating solution ..."

Please answer the following question for me: If I wanted to use today's modern plating solutions, where would I obtain the necessary gold salts (I think that's what they are called) and the other necessary chemicals to make the solutions?

Doyle Whitaker
- Brooklyn, New York, USA


August 2013

A. Hi Doyle. I think there is an assumption here that people still make gold plating processes by buying individual gold salts and other commodity chemicals and mixing them. But these days we tend to buy a ready-to-go precious metal plating solution, or perhaps a make-up solution and a replenisher. Large buyers would go to plating process suppliers like our supporting advertiser Technic; small buyers would go to jewelry supply distributors like Grobet to buy processes like the Clean Earth plating solution previously illustrated halfway up the page, or to hobby-scale suppliers like our supporting advertiser Gold Touch.

For brush plating it is usual to go to a supplier who offers both the equipment and chemicals, per the banner ad at the top of the page. Good luck.

Regards,

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


September 9, 2013

A. Somewhat late response:

(1) POTASSIUM FERROCYANIDE MSDS CAN BE OBTAINED VIA WWW - MIXING IT WITH WATER ( OR ALKALINE compounds) IS NOT DANGEROUS, BUT NEVER TRY TO MIX IT WITH STRONG MINERAL ACIDS!

(2) ??????

(3) 24 ct

(4) YES

(5) YOU CAN USE GLOVES AND SAFETY GOOGLES

Hope it helps and good luck!

Goran Budija
- Zagreb, Croatia

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