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letter 6354

What makes up silver plating solution?



A discussion started in 2000 and continuing through 2017 . . .

(2000)

Q. My son is doing a research project in electroplating silver plated objects. We have determined that the silver electroplating solution is made up of either silver nitrate or silver chloride. Can anyone tell us what makes up the other parts? What liquid is added to the silver material. Also he needs to know the parts measurements (for ex. 1 part silver nitrate to 2 parts water etc.)

Thank you

Celeste Butler (Mom with no chemical knowledge)

Celeste Butler
- Brooklyn New York USA


(2000)

A. The basic ingredients of a conventional silver plating bath are silver cyanide and sodium cyanide. Other ingredients are added for better conductivity, brightness, etc. but are usually proprietary (composition not published).

There are non-cyanide baths available, but not as widely used, that use organic salts of silver. Again, the exact composition is proprietary, but some contain succinates.

Hopefully you are not considering making up one of these for home use or in a school project. They are toxic and heavily regulated.

Bill Vins
microwave & cable assemblies
Mesa (what a place-a), Arizona 


(2000)

A. Celeste,

Many school projects consider immersion silver deposition to be electroplated silver. The response by Mr. Bill Vins above is indeed correct. The silver plating baths used in industry are highly toxic and contain cyanide.

However, some school demonstrations use a liquid solution of silver nitrate to put a thin immersion coating of silver on copper parts (in many cases, pennies). I still use the caution from Mr. Vins. Silver nitrate is considered an oxidizer and MUST be used only with direct supervision of a Chemistry Teacher. Also, most schools have stringent rules concerning what chemicals may be brought onto the premises. Questions should always be phoned into the school office first, for permission to proceed further.

Electroplated silver can be deposited with much greater thickness than immersion deposits. Immersion deposits normally lack good adhesion, and are not desirable for most professional Surface Finishers.

ed budman
eb sig
Ed Budman
- Pennsylvania



October 9, 2012

!!
I've seen several questions on the forum regarding the formulation of homemade silver plating solutions, especially for touch-up applications, repairs, etc. Well, I did a little research recently because I needed to do some silver brush plating, and it turns out, that a simple solution of silver nitrate is all one needs to do satisfactory silver plating. No cyanide based solutions, or "Proprietary" (seems to be an important word around here, LMAO) formulas are needed. After a couple of on-line purchases, I was able to determine the constituents of the silver brush plating solutions of three of the larger retailers of said products. (Sometimes working at a place with an in-house analytical lab has its benefits) two out of the three use nothing more than a solution of silver nitrate. That's it. No brighteners, no nothing. Generally, the solutions had a density of around 1.2 - 1.25 which works to about 25% to 30% nitrate in the solution. I found this quite funny, since I've seen posts here on this forum on more than one occasion from "experts" that claim that silver nitrate flat out will not work as a plating solution. Well, I can tell you from research, and now from experience, that it does indeed work quite well.

I just thought I would throw that out there for anyone interested.

Derek Hall
Hobbyist - Atlanta, Georgia, USA


October 2012

thumbs up signThanks, Derek. Some if not all consumer marketed "instant resilvering" dips are silver nitrate or based on silver nitrate (see FAQ: Silver Plating at Home"), but it is interesting to learn that similar pure silver nitrate proved acceptable for you for brush plating as well. But our mission is certainly not to crowdsource industrial espionage, so continuing discussions need to remain generic.

It remains true that 90% of all silver plating is cyanide based as it has been for a hundred years, but brush plating involves a different dynamic than regular tank plating and perhaps it works. Silver nitrate probably will not adhere properly in tank plating, and I still am led to believe that it's quite hazardous to electrolyze nitrate solutions, so I hope that the elementary school students who have posted here about their science project of immersion plating silver onto copper aren't tempted to electrolize their silver nitrate baths. Thanks again.

Regards,

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


October 21, 2013

A. This is in response to Derek Hall's post above. I read his post and as a result, purchased silver nitrate crystals. Derek claims that commercial plating solutions for hobbyists are made of silver nitrate. I don't know if he was referring to instant plating solutions or electroplating solutions, but in a thread about silver electroplating I assumed he was discussing the latter.

I have mixed up several different solutions of silver nitrate and applied them using a brush plating transformer and anode from a large seller of brush plating equipment in the US. Result? A brilliant silver finish which rubs off with car wax. Oh yeah--and black fingers. A commercial solution I bought does not turn fingers black and it adheres to the metal it is plated onto. I think this pretty much proves that silver nitrate is not what you want to use for electroplating.

Steve Close
- Moses Lake, Washington, USA



May 6, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Respected Sir,
I want to know how to do good silver plating. How many type of Chemicals in Silver Water? Please tell me about this.

Thanks,

Pankaj Soni
- Jaipur,Rajasthan, India


mfg
Click the graphic for the on-line version of the Metal Finishing Guidebook

May 6, 2013

A. Hi Pankaj. The overwhelming majority of silver plating is done with potassium silver cyanide or sodium silver cyanide solutions.

Generally there are good-sized chapters about silver plating in most plating textbooks =>
so it's too detailed a subject to compress into a paragraph or two. But if you can tell us what you are trying to silver plate and why, so that we can limit the subject a bit, maybe we can help. Good luck.

Regards,

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



September 23, 2014

Q. Respected sir,
I want to know how we can do good silver plating for silver jewellery. How many types of chemicals are there in silver water?
Please answer my question.

Nagabhushana Chary
- kothagudem, andhrapradesh, india


Clean Earth Silver Plating Solution

September 2014

A. Hi Nagabhushana. As I noted, the overwhelming majority of silver plating is done from potassium silver cyanide or sodium silver cyanide solutions. But yes, there are additional proprietary plating solutions available for silver plating from suppliers like EPI (Electrochemical Products Inc.) [a finishing.com supporting advertiser] and Zinex. There are also immersion silvering processes based on silver nitrate, and proprietary brush plating processes which might or might not be based on silver nitrate. The best path forward is probably to buy a proprietary silver plating process from a plating process supplier, which will come with a technical data sheet, and hopefully some help.

A one-paragraph reply in a forum can't cover what we would need to cover to explain silver plating in detail, and it is no substitute for a good electroplating book. If the previously referenced on-line version of the Metal Finishing guidebook wasn't sufficient, Lowenheim's "Modern Electroplating" [link is to info about book at Amazon] has a rather good 18-page chapter on silver plating, with a good deal of generic information; and the "The Canning Handbook" style= [link is to info about book at Amazon] is one of my perennial favorites, with a 22-page chapter on silver plating. Best of luck.

Regards,

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



March 23, 2015

Q. Dear sir,
I do silver plating on stainless steel.

wikipedia
Superfinishing

But it's a problem:
Silver plating/finishing is not good; it's dull.
How to do super finishing?
What is the chemical in the super finishing. Please help me.

sam chavam
- maharastra pune


May 1, 2015

A. It's always advised prior to silver plating that acid copper plating needs to be done.

KP

Karthikeyan Ponnusamy
- Bangalore, Karnataka, India



December 8, 2015

Q. Hello.
I want to know:
Can we add another layer of silver plating on already silver plated material?
In my case,
base material is copper.
I have plated 5 micron silver.
I want to add another 10 micron silver on it to make it 15 micron.

If we cannot add layer on layer, please elaborate the reason.

Thank you.

Dhaval Suthar
- Vadodara, Gujarat,India



Brush Electroplating using Silver Nitrate. What goes into plating solution?

March 9, 2016

Q. I'm using hobbyist brush plating equipment. I've been disappointed in the shelf life of the silver plating solution, which becomes water with silver BBs in the bottom after five months. I'd like to be able to mix up my own fresh solution. I read in a post on this forum that silver nitrate solution works, but my experience was that silver nitrate dissolved in water simply didn't plate. I'm wondering if there's another type of solution I can use that might work better than an aqueous solution, or if there's another silver compound (silver chloride perhaps) which would be better suited to brush plating. $40 for a bottle that goes bad after a few jobs just isn't paying off for me.

Thanks

Steve Close [returning]
Hobbyist - Moses Lake, Washington

March 2016

"THE" brush plating book:
Electrochemical Metallizing

Hi Steve. Rubinstein's "Electrochemical Metallizing" =>
seems to imply that adhesion requires a bonding underlayer of "Nickel-Neutral", a mildly alkaline nickel plating solution. I am not personally convinced yet that you can beneficially electroplate silver from straight silver nitrate despite the claim above by Derek Hall.

Addendum 3/10/16: Rubinstein does not say or imply that Selectrons non-cyanide brush plating solution was based on silver nitrate. Upon reading Chris' outstanding followup, and re-reading the thread, I now realize that my posting implies that it was silver nitrate; sorry, I have no basis for that implication.

Regards,

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


March 10, 2016

A. Silver is typically purified by the electrolysis of impure silver anodes in a solution of from 20 g/l to 80 g/l of silver as silver nitrate. The only other chemicals in the solution are maybe a couple of percent of free nitric acid and from 0 to about 90 g/l copper as copper nitrate. The cathode is usually 300 series stainless steel sheet.

The anodes dissolve, the contaminants (usually copper) remain in solution, and the silver deposits as non-adherent loose crystals that are quite dense. The very loose, separate crystals are scooped out of the solution, filtered, rinsed very well, melted, and cast into bars. It is possible to get 99.99% pure silver in this cell.

The cells are of 2 types: The Balbach-Thum cell, where the electrodes are arranged horizontally - the cathode covers the bottom of the tank and the anodes are in a basket about 4.5" above the cathode. The other type is the Moebius cell, where the electrodes are arranged vertically, much like a typical plating tank.

I have run these cells for many years under great variations of solution composition and have never seen an adherent solid deposit produced.

Chris Owen
- Nevada, Missouri, USA



May 2, 2017

Q. I am regularly using silver bath with potassium cyanide chemistry. Can I use citrate based bath for silver plating? Can anyone give recipe for that?

vaishali vaghela
SAC, ISRO - ahmedabad, gujarat, India


May 10, 2017

A. Hello, I am not aware of any non cyanide citrate based reputable precious metal supplier for electroplating who could help you. I do know of a few baths that use succinic acid and a sulphuric acid with a sulphuric acid dip post quencher.

Mark Baker
Process Engineering - Phoenix, Arizona USA



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