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Strip and recover silver from silver plated steel or stainless
Current postings:March 7, 2022
Q. I have a large quantity of silver plated tableware from which I wish to remove the silver plate. The base metals will be variable, including brass, copper, nickel, and stainless steel. I've seen demonstrations on line using sodium chloride as an electrolyte. I wish to avoid the formation of silver chloride so I thought of using sodium hydroxide. I don't have a laboratory grade fume hood and don't wish to use any form of cyanide.Dale Davis
Retired Physics/Chemistry teacher, now a hobbyist. - Addison, Illinois
Closely related Q&A's, oldest first:November 10, 2011
Q. I am working in a electroplating company. we are doing silver plating also. we have some electroplated stainless steel and steel based material. now we want to extract the silver from the material. What is the best and easiest way to extract the silver? Thanking you.Gandhi Govindarasu
Plating shop employee - Singapore
November 11, 2011
You first treat your silverplated material in nitric acid which will dissolve your silver in nitric acid. Then by addition of NaCl or HCl you will get silver chloride; then reduce that AgCl using iron plates to get silver metal (cement silver).
- Mumbai, India
A. Using nitric acid, as explained in the post by Bhupesh Mulik, will work fine for stripping silver from most stainless steels. However, nitric acid will attack mild steel under many conditions, depending mainly on the steel alloy, the strength of the nitric, and the temperature of the solution. Once the steel starts dissolving, the reaction will generate much heat and it can become very uncontrollable.
A much better way to strip silver from mild steel is to use a cyanide based nickel stripper. It can also be used to strip the silver from the stainless. Using the immersion solution below, when the silver in the solution builds up to an economical point, it can be recovered by the addition of 325 mesh zinc dust. The weight of zinc dust needed is about equal to the weight of silver in solution. It may take more if the sodium hydroxide (NaOH) content is high. You should use some NaOH (I would say at least 5-10 g/l) to prevent any possibility of the evolution of hydrogen cyanide gas (extremely toxic).
Immersion Solution from Modern Electroplating:
Nitroaromatic compound (most use Ludigol = m-NBSS) - 60 g/l
Sodium Cyanide - 120 to 180 g/l
Sodium Hydroxide - 0 to 25 g/l
Temp - 60 to 75° C
You can also use an electrolytic solution. The parts will have to be wired (steel wires), racked, or placed in a barrel plater. The silver should deposit on the cathode.
Electrolytic Solution from Metal Finishing Guidebook:
Sodium Cyanide - 90 g/l
Sodium Hydroxide - 15 g/l
Make parts anodic (+) at 2 to 6 volts
I would use stainless sheet cathodes (-)
- Nevada, Missouri, USA