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Silver Tarnish and Tarnished Claims

Silver is more than just an object of beauty. It’s the stuff of memories.

Silver is more than just an object of beauty. It’s the stuff of memories. Prior to digital photography, all picture taking relied on compounds of silver. The reduction of silver ions to metallic silver by the action of light that is at the heart of the chemistry of photography. Silver is in fact so light sensitive that a crystal of silver chloride could detect the light of a candle on the moon! That’s what they say anyway. I haven’t tried it. But I certainly have tried cleaning silver. The metal of course tarnishes. That’s because it reacts with small amounts of hydrogen sulfide in the air to form black silver sulfide. What’s the answer?

Well, you can remove it with a generous amount of elbow grease by rubbing with a fine abrasive. Or you can dip silver objects into a solution of thiourea and sulfuric acid to dissolve away the silver sulfide. Or you can make use of some very clever chemistry. Just wrap the silver to be cleaned in aluminum foil and drop it into a glass bowl filled with boiling water to which a spoonful of washing soda has been added. Within minutes the tarnish disappears.

There’s some remarkable chemistry going on here. The silver sulfide is converted back to metallic silver as the aluminum strips the sulfur away, forming aluminum sulfide. This method has the added advantage of not removing any silver at all. However the silver that gets redeposited may not shine as brightly as the original surface. So this method, while by far the easiest, may not be suitable for grandma’s fine jewelry. 

While silver is a fine material for jewelry, it does not cure any disease. That may sound like a strange comment but recently “nanosilver” or “colloidal silver” has become a hot item thanks to some clever pseudoscientific promotional lingo. Silver has been shown to have antimicrobial properties, begins the sales pitch, and then goes on to describe how silver is used in water purifiers and is even woven into socks to reduce odour caused by microbes. True enough. But deodourizing socks is a long way from destroying the Ebola virus in the body, which is one of the claims. Colloidal silver can, however, do something. It can cause an irreversible condition known as argyria in which skin colour is permanently altered by deposits of silver.


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