What makes up silver plating solution?

? Hi Mohan. Sorry but your message is too short for me to understand. I apologize but don't know what you are asking. But the article in the Metal Finishing Guidebook referenced below mentions the main ingredients in four different non-cyanide processes.

Luck & Regards,

A. Hi Charles. On the one hand, trying to 'improve' a commercially available process often doesn't work out well; a change may shorten rather than extend it's life :-(

But on the other hand, yes, soluble silver anodes are commonly used in silver plating, and it's not that big a deal if it doesn't work :-)

Luck & Regards,

A. Hi Linda. You should get the datasheets for the cleaning solution & plating solutions, and the operating manual for the rectifier from the manufacturers of each. You can get general instruction on silver plating from the on-line version of the Metal Finishing Guidebook, as previously noted.

But what exactly are you trying to do? Plate copper or brass jewelry, plate stainless steel, plate aluminum, re-plate flatware, do electroforming, repair electrical contacts? There are many books about electroplating, and each has a chapter(s) of many pages on silver plating, covering the gamut of situations; so you have to tell us what you're trying to do so we know which of those pages aren't relevant to your needs :-)

Luck & Regards,

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.

A. Celeste,

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.

Thanks, Derek. Most "instant re-silvering" dips are silver nitrate or based on silver nitrate (see FAQ: Silver Plating at Home"); it is interesting to learn from you that pure silver nitrate proved acceptable for brush plating. Our mission is certainly not to crowdsource industrial espionage, so discussions need to remain generic, not aimed at blowing trade secrets.

Well over 95% of all silver plating is cyanide based as it has been for a hundred years, but brush plating involves a different dynamic and perhaps it works. Silver nitrate probably will not adhere properly in tank plating. Thanks again.

Regards,

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.

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

Generally there are fat chapters about silver plating in most plating textbooks so it's too detailed a subject to compress into a paragraph or two. Plus random experimentation with silver compounds can generate explosive silver fulminates :-(

But if you can tell us what you are trying to silver plate, how thick, and why, so that we can limit the subject a bit, maybe we can help with specific questions. Meanwhile, the digital version of the Metal Finishing Guidebook has a nice little 7-page summary, and it's free! -->

Good luck.

Regards,

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 get a proprietary silver plating process from a plating process supplier, which will come with a technical data sheet, and hopefully some help.

A one or two-paragraph reply in a forum can't cover how to formulate and test a silver plating solution; plus you probably need to do a silver striking step first or you'll suffer poor adhesion and costly contamination. Please review the short silver plating chapter in the previously referenced on-line version of the Metal Finishing guidebook and ask us follow-up questions. Or if that source wasn't sufficient, Lowenheim's "Modern Electroplating" [adv: this book on AbeBooks, eBay, Amazon] has a rather good 18-page chapter on silver plating, with a good deal of generic information; and The Canning Handbook [on eBay, Amazon, AbeBooks] is one of my perennial favorites, with a 22-page chapter on silver plating. Best of luck!

Regards,

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

KP

A. Hi Dhaval. Yes you can plate silver on silver as long as you realize a fundamental principal of proper electroplating: you can only electroplate onto metal, not onto tarnish or oxidation. If you can remove the tarnish you're good to go.

Luck & Regards,

Hi Steve. Silver chloride is insoluble, so forget that one. 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 sort of implies that it was silver nitrate; sorry, I have no basis for such an implication.

Regards,

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 [affil links]. 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.

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 sulfuric acid with a sulfuric acid dip post quencher.

A. Hi. EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser] offers two non-cyanide alkaline silver plating processes, and I believe that Technic and Zinex offer non-cyanide processes as well. I believe that these were originally developed for industrial electronics applications and I can't claim that they do or don't meet aesthetic requirements for decorative silver plating.

Luck & Regards,

A. Hi Mohan. This is one of the specialties of EPI / Electrochemical Products Inc. [a finishing.com supporting advertiser]. I believe Technic and Zinex offer it. I assume that some Indian suppliers can offer it to you as well.

Luck & Regards,