Jewelry cleaner turned silver black

A. Hi N,
Without knowing what the ring was made of (silver?), whether it was plated with another material, etc., it's hard to know what went wrong and how to fix it, but lots of people have 'fixed' silver rings by doing nothing more complicated than rubbing it with tooth paste on a wash cloth.

Please search the site for "toothpaste silver" if you want to read more before trying it. You may wish to send a photo of the ring to mooney@finishing.com for posting here and/or tell us more about the ring. Good luck.
Regards,


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

A. You can use slightly acidified 100 gm thiourea [on eBay or Amazon] / 1 lit water solution (thiourea is carcinogenic substance!), or you can use 300 gm sodium thiosulphate [on eBay or Amazon] /1 lit water solution.

Q. I am looking to remove some discoloration from a silver alloy using the Sodium Thiosulphate formula that was recommended above, but I have no experience with this chemical. Will this chemical cause additional discoloration if left on the part too long? Will this chemical remove other metals such as gold? Can you use this chemical to electrochemically remove material? Thank you for any help you can give.

Cameron Kivela
- Boulder, Colorado, USA
October 9, 2015

A. Silver does form a stable water soluble complex with thiosulphate. There's a prep method for analytical samples to be analyzed for Ag that uses it.

Add electricity to the mix? You might try making the workpiece mildly anodic in a Na2S2O3 (sodium thiosulphate [on eBay or Amazon] bath) if simple immersion doesn't work.

Of course, cyanide works better. I used to clean my girlfriend's silver jewelry with a little KCN dissolved in warm water. No polishing needed, just a dip. But you might not want to play with that. Hard to beat the good old toxic stuff. :)

Dave Wichern
Consultant - The Bronx, New York

Ed. note: Indeed, cyanide is only for trained chemists in proper facilities.

A. I'm doing silver cleaning job everyday in my area which works best and fast. I do cleaning & repolishing about 1 kg everyday for other goldsmiths.

Only if your jewelry is without stones then only use following process:
Use 15% to 25% sulfuric acid in water and then if you can heat the silver jewelry and then directly put into the acid it'll come out white smoke and then just put for 5 to 10 mins, then rinse and then do the polishing or put into tumble machine [on eBay or Amazon] with very small amount (5 ml to 10 ml) of acidic solution.

If the jewelry is made in Italy then it'll need another process which is long and not good for health.

I advice you don't do this at home -- please use in workshop only.

Good luck,

A. I don't know who did that to you [suggested overnight in sulfuric acid], but it was mean.
Use a fine polishing compound, Brasso [on eBay or Amazon] or similar, buff to luster.
Next time, get Tarn-X [on eBay or Amazon] and dilute.
Alternately, you can use some hair shampoos to keep your jewelry clean, I know that Head and Shoulders as well as Selsen Blue work in a 1/10 mix for light cleaning.

? It seems funny that those selenium sulfide shampoos would work, Mark. With their sulfide content they would seem to be mild darkening agents rather than lightening agents, but I haven't tried it.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Non-professional method I use in the kitchen:
Plastic flat-bottom container, lay aluminum foil in the bottom, fill with hot (120 °F) salt water, add tarnished silver. The silverware turns nice and shiny by the time the water cools. note: the silver has to be in contact with the aluminum.

A. You can use boiling 5% solution (50 gm borax [on eBay or Amazon] , 1 lit water) -- simple and very safe ... Good luck!