Silver is beautiful, but it can lose its shine over time as it becomes tarnished. Tarnish is a layer that forms on silver, making it look dull or discolored. Silver does not oxidize in the traditional sense (forming rust in reaction to oxygen, as iron does), but it does undergo a reaction with certain elements in the environment which leads to tarnishing.
The two most common causes of tarnish are sulfur and chlorine, but they work in different ways and create different results.
How Sulfur Causes Tarnish
Sulfur is a major reason why silver tarnishes. You can find sulfur in the air (especially in polluted areas), certain foods like eggs and onions, and even materials like wool. When silver comes into contact with sulfur, a chemical reaction occurs, creating silver sulfide (Ag₂S). Tarnish is silver sulfide!
Silver sulfide shows up as a dark, black layer on the surface of the silver. At first, the tarnish may look yellowish, but over time, it gets darker. Warm and humid conditions can make this process happen faster. When people talk about tarnish, this is usually what they mean. (It is also what people mean when they incorrectly talk about silver “oxidizing”.)
How Chlorine Causes Tarnish
Chlorine tarnishes silver in a different way. You can find chlorine in bleach, swimming pools, and even tap water. When silver reacts with chlorine, it forms silver chloride (AgCl), which looks like a whitish or grayish film.
Chlorine tarnish happens more quickly than sulfur tarnish, especially if the silver is exposed to strong sources of chlorine, like pool water. If you’ve ever worn a silver bracelet while swimming in a pool, you might have noticed this.
How to Remove Tarnish
The good news is that you can remove tarnish from silver with an easy method that uses baking soda and aluminum foil. This process works because of a chemical reaction that turns the tarnish back into shiny silver. Here’s how to do it:
- Get Your Supplies: Line a bowl or dish with aluminum foil, non-treated side up. Use a non-metallic bowl like glass or plastic.
- Add Baking Soda and Hot Water: Sprinkle a few tablespoons of baking soda into the bowl, then pour in very hot (but not boiling) water. The water should be enough to fully cover your silver item.
- Place the Silver in the Bowl: Make sure the silver touches the aluminum foil. This is important for the reaction to work.
- Wait a Few Minutes: The baking soda and aluminum will cause a chemical reaction that removes the tarnish. You might notice the tarnish moving to the foil. You might also notice a rotten-egg smell, which is the sulfur
- Rinse and Dry: Take the silver out, rinse it with clean water, and dry it completely with a soft cloth.
This method is safe for most silver items and works well for both sulfur and chlorine tarnish. Basically, what happens is the sulfur or chloride are more attracted to aluminum than to silver, so they leave the silver and are re-deposited on the aluminum, leaving your jewelry tarnish-free!
With a little caution and occasional maintenance, your silver jewelry should be able to keep its shine, tarnish-free, for years.
