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topic 3755

Clear coating of Silver for Anti-tarnish



A discussion started in 2003 & continuing through 2017

(2003)

Q. I am looking for a clear coat that we can apply over sterling silver so that it will not tarnish. We would like this coating to last at least 1 year - longer if possible.

Mike Masciarelli
makes silver jewelry - Marlboro, Massachusetts


(2007)

RFQ: I am looking for a clear coat for my silver plated jewelry. I have the plater and want to use a non spray coat.

Diane D [last name deleted for privacy by Editor]
Jewelry maker - La Mesa, California, USA
outdated


(1999)

Q. Regarding old silver/silverplated flatware and holloware.

What is the most economical way to apply a clear coat/lacquer finish to prevent tarnishing. Is a clear coat or lacquer the best finish? What other options are there? I have heard of E-coating, would this be suitable?

We are in the business of producing many household items, recycled from flatware and holloware. One of our main lines is wind chimes, so the element factor would come in to play on deciding what finish would work best.Our goal is to offer an extra service of sealing/finishing the piece(s).

Thank you!

Stuart M. Torkington
- Havana, Florida


A. Hi Mike, Diane, Stuart. As you probably realize, there is very rarely actually a "best" way. If there were, the other ways would quickly fade out of existence.

Some ways to anti-tarnish silver include organic preservatives, chromate treatments, flash plating with rhodium, and clear coats of many types including e-coating, UV-curable lacquer, 2k clearcoats, and other lacquers and clearcoats. Let's very briefly introduce them:

Preservatives like VCIs (volatile corrosion inhibitors) might be helpful in a showroom or museum case and during storage. Chromate treatments might be good for electronics, but should not be used on jewelry or food service because of toxicity. Rhodium is a very expensive precious metal that is bright and tarnish proof; a thin layer electroplated onto the silver is very effective in deterring tarnish but is probably impractical for large items and outdoor exposure.

Clearcoats are transparent lacquers or paints applied and cured by a variety of methods, each method having some advantages and disadvantages. E-coating is a way to apply an exceptionally thin and even clearcoat but the equipment is expensive and somewhat complex (you may find letter 45245, "E-coating for silver jewelry", interesting). More accessible to hobbyists would be UV (ultraviolet) cured lacquers because the coatings are hard and durable but the curing machines are cheap (UV cured lacquers/nail polish are applied to women's nails by manicure shops). 2k (two-component) automotive clearcoats are another possibility and widely available at auto body shops; mixing the two components initiates a chemical reaction that hardens them. Then there are solvent based or water based lacquers which can dry in the air or in an oven; there is nothing really wrong with these, it is just that "drying" is just one of many ways for a finish to cure and, like every other method, it offers strengths and weaknesses.

For the case of Mike's silver jewelry, I'd probably look at rhodium plating first; for Diane's non-spray clearcoat, e-coating sounds in order; for Stuart's wind chimes, I'd probably look first at the 2k automotive clearcoats first since they are made for outdoor exposure and large items, and have been proven on millions of automobiles. Good luck all.

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



Chromating of silver jewelry

electrolytic chromate
(2001)

Hi, We produce nickel free costume jewelry using our in-house tin/lead and zinc casting machines and have a problem with the shelf life of our plated products. After silver or gold plating, our surface finish is remarkably bright and just the way we want it, but there is no way we can make the finish last. People have suggested that we use Clear Electrophoretic Lacquers over our final layers of gold or silver plating, but we do not want to get into the complication of starting this separate process.

I was in Korea a few days back and noticed that after silver plating the plater takes it to a bath which is yellow in color and has stainless steel anodes =>

On passing current there is no deposition of any sort on the plated part and after passing the current and taking out the piece the finish of the pieces is the same as it was before it was plated, but what I understood from the plater was that the plated part does not tarnish so easily after that and is made up of a mixture of three chemicals. The plater was unable to explain to me the contents of the bath because of our language restrictions since I do not speak Korean and the plater spoke extremely limited English.

I am attaching a picture of the bath with this mail so if anyone finds it familiar then I would appreciate some more information on the bath. Thanks,

Roger K [last name deleted for privacy by Editor]
exports - New Delhi, India


(2001)

A. The anti tarnish process that you noticed is a electrolytic chromate process. It is used for gold, silver and electroless nickel. Ask your supplier about it. It is for sure cheaper than clear coat although less effective.

sara michaeli
sara michaeli signature 
Sara Michaeli
chemical process supplier
Tel-Aviv, Israel



June 2013

A. Hi. Roger's inquiry is over a decade old by now, so I would update it by noting that chromate treatments are probably inappropriate for jewelry because chromate is considered a carcinogenic toxin. Probably there is very very little chromate compound on the jewelry, but there really should be none. It is possible that the process Roger observed was being applied to electronic components rather than jewelry; and again, there is no "right" anti-tarnish treatment for all situations.

Regards,

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



Is lacquering safe for food service silverware?

Silver Protection Strips

(2006)

Q. I want to have my silver pieces refinished. Some will be used with food: trays, spoons, etc. I also want to minimize having to polish the pieces, so I'm thinking of having them lacquered at the last stage. Is this safe for food consumption?

Rene Dalandan
musician - Orangeburg, New York


(2006)

A. Keep your silver clean and try 3M silver protection strips. In principle, clearcoat can be used only for exhibition pieces. Visit society of american silversmiths website(www.siversmithing.com/).
Good luck!

Goran Budija
- Zagreb, Croatia



What clear coating for silver jewelry will never yellow

June 7, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Which is the most suitable clear lacquer for silver jewelry. It shall not have yellow touch and should provide good tarnish resistance. Thanks.

Ayush Agarwal
- New Delhi, Delhi, India


May 20, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We love them, but ladies are tough on us. Ladies can be highly abusive to the jewelry we manufacture.

We are looking for a very hard, scratch resistant, gloss clear, non yellowing, EVER, coating.

The coating will be used to protect sterling silver and/or precious stones such as Mother of Pearl (Shell), etc.

Thank you for your consideration,

Jon

Jon Olson
manufacturer - Presque Isle, Wisconsin


May 2014

A. Hi. As mentioned earlier in the thread, there are many approaches based on end use, volume, capital cost, etc. If I was a medium to large manufacturer of jewelry, I would spend a lot of time researching UV/EB (radiation cured) clear coatings such as are now used on the plastic lenses of most automobiles. The scratch resistance and non-yellowing is quite impressive. The equipment for true professional application probably costs a hundred thousand dollars though. See what Radtech can tell you. Good luck.

Regards,

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


May 23, 2014

A. Try ProtectaClear by Everbrite [a finishing.com supporting advertiser]. Hope it helps and good luck!

Goran Budija
- Zagreb,Croatia


June 6, 2014

A. Rhodium.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg,
      South Carolina



June 9, 2014

A. Try argentium® sterling or platinum sterling® silver alloys,somewhat expensive but tarnish resistant ... Hope it helps and good luck!

Goran Budija
- Zagreb,Croatia


August 20, 2014

A. Try to make Passivation, such as EVABRIGHT (Enthone) .
Good luck

Sittikorn Rakjai
- Bangkok , Thailand


June 20, 2015

A. Dear all,
I read all comments about anti-tarnish of silver, but can't justify a complete answer.
Actually here is how I plated silver on brass chain which has a bright stone on it, when I applied clear coat the stone was cloudy after dipping, and chain was somewhat hard that's no issue.
Sodium dichromate: people are using it here for silver anti tarnish with current. There is no other easy method to seal silver plating and its tarnishing.

mustanser hashmi shah g
silver plater - lahore pakistan


June 2015

thumbsdown Hi Mustanser. Sorry, but I can't agree. Sodium dichromate (hexavalent chromium) is carcinogenic and should not be used on jewelry. If you are certain that all traces have been converted to metallic chromium, that could be a different story. Rhodium plating is a better answer.

Best Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


April 7, 2016

A. Hi, I am a semi retired paint chemist and busy on a "review of Silicate Coatings". Silicate coatings are inorganic and contain no allergenic or other organic compounds as you will find in the mentioned organic clear coats.
Unfortunately I do not have supplier details but you could do an internet search for "Clear Silicate Metal coatings".
As Silicates are really "Glass coatings" they are hard and long lasting. Application would not require special equipment or knowledge.

Ken Marx
- Durban. South Africa


February 10, 2017

A. Umicore has a product called Sealing 691 which provides anti-tarnish and light scratch resistance for silver (sorry for mentioning a name brand product, but I wanted to include that the product I mentioned does not contain chrome).

Julie Richardson
- Houston, Texas USA


June 26, 2017

A. Tarnish-Me-Not will work best.

Benjamin Soyer
- Boston, Massachusetts, USA

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Ed. note: Presumably people realize that if we were to print "I tried brand Blahblah and it sucks", we'd hear from their lawyers. So whenever a product is mentioned by name, you know that the reviews go unbalanced and thus may be unrealistically favorable. Sometimes postings even come from the IP address of the product's website. That is one of many reasons we ask people to try their best to discuss technology rather than insert brand recommendations into this on-line technical journal :-)



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