Tuesday, 2 December 2014

The Best Method to Untarnish Silver

Some of my fabulous silver (and some gold).
Like me, I'll bet you've got some beautifully romantic pieces of Sterling silver jewelry. Or maybe you inherited a lovely set of silverware from your grandmother. Or maybe you're on a Quest, and when you finally find the Silver Sword of MacGuffin, you discover it terribly tarnished.

Alas, silver tends to tarnish with age.

Here is one of The Best Methods for untarnishing your silver. (I'll explain why later).
  1. Fill a saucepan with 1.5 litres1 (half a gallon) of water. Add 1/4 cup of baking soda and 1/4 cup salt (NaCl). Bring to a boil.
  2. Line a second saucepan or a large glass bowl with a sheet of aluminium foil. 
  3. Place your tarnished Sterling silver jewelry (or magical sword) on the foil. It must have contact with the foil, the more, the better.
  4. Pour the boiling baking soda water over your jewelry and let it sit for a few minutes. The tarnish will disappear. If a piece of jewelry is severely tarnished, you may need to reheat the water or let the solution sit longer. 
  5. Once silver is untarnished, remove from pan (with tongs or a spoon, as it may be very hot).
This is how I keep my silver bright and shiny, especially as I have a bad habit of taking magical silver swords into brimstone-ridden hellmouths or wearing my silver rings into sulfer-ridden swimming pools.

Here's How It Works

Tarnish is silver sulfide (Ag2S). Tarnish happens when sulfer from the atmosphere, from a swimming pool, from food, etc reacts with the silver of your jewelry (or your silver teaspoons).

Many other methods of silver polishing removes that layer of silver sulfide. This is less than ideal. Yes, it's removing that tarnish, but it also removes a layer of silver as well. We don't want that.

My method above only removes the sulfer. It leaves the silver behind.

Essentially, what's happening is an electrochemical reaction. What we are doing is pulling the sulfer from the silver sulfide and making aluminium sulfide (Al2S3). Sulfer wants to be aluminium sulfide more than it wants to be silver sulfide. Therefore, when presented in an ideal environment (the hot water & soda/salt), it moves to the aluminium foil.

Want to know more about the science behind this? Learn how oxidation and reduction make it work.

Has Her Grace mentioned just how much she loves science?

1If you are untarnishing magical enchanted silver swords, you may wish to increase this recipe at least four-fold to ensure complete coverage of the sword by salt/soda solution. Also increase the amount of aluminium foil to maximise surface contact. And you'll need a larger pan. Maybe a bathtub.

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