Why Does Silver Tarnish?
Contributed by Joshua McMorrow-Hernandez
Tarnish happens most quickly when a silver alloy comes into contact with moisture, sulfur, and other components in the air. Silver will usually tarnish more quickly in places with higher humidity or in areas with higher levels of air pollution.
Silver is one of the most treasured precious metals, having been mined since 3000 BC in Turkey and Greece. Silver finds its way into everything from coins and jewelry to medical equipment and photographic material.
But for all its beauty, silver often tarnishes, much to the frustration of its beholder. We all want our silver products to retain their lustrous appearance like when they were new.
So, how does silver tarnish? Is there a way to safely clean silver coins when they do tarnish? How does tarnish affect the value of silver coins?
How Does Silver Tarnish?
Pure silver resists tarnish. However, one almost never encounters pure silver. It is far too soft for use in items that require durability, such as coins.
Therefore, silver is generally mixed with other metals in an alloy form. This makes the metal much harder and more suitable for day-to-day wear. Most commonly, it is mixed with copper, and copper is a highly reactive metal. Thus tarnishing is usually because the other metals in the silver alloy are reacting to the surrounding environment. It’s the natural chemical reaction metal has when exposed to air and the elements it contains.
You can help prevent silver from tarnishing by storing it in a cool, dry location free of air impurities. Do not store silver coins or other precious metal items in places like:
- near equipment that produces heat or emits gases
It’s also a good idea to keep silver away from chemicals such as:
- hair sprays
Can You Safely Clean Silver?
A lot of people use polish to remove tarnish from their silver items. The question remains, is it safe to clean silver? Is it recommended to do so?
That depends on what we’re talking about cleaning. Most people want their fine silverware and jewelry to retain its silver appearance. There are many resources that explain how to safely polish these pieces. But it’s a bit of a different approach when it comes to coins.
In the world of numismatics, cleaners are virtually always a big no-no. Traditional silver polishes employ abrasives to remove both the silver sulfide and a thin top layer of silver. Of course, removing that top layer of silver is a permanent action—you can’t put that silver back on the coin. Thus, using an abrasive silver polish causes irreparable damage. It is never recommended for removing tarnish (or toning) from a coin. Furthermore, most coin collectors actually prefer that a coin have its original patina.
For many collectors, an old silver coin that looks unusually new and bright just doesn’t look right. (That's unless the coin is a well-preserved Mint State specimen.) In the interest of originality, it is also frowned upon to use less physically abrasive silver dips and solutions. These products claim to remove the tarnish alone, yet they can still leave a physical impact on the coin.
Oftentimes the solution etches the surface and affects the appearance of flow lines on the coin that help render its luster. So, considering all the risks that can come with attempting to remove tarnish, it’s best to avoid cleaning silver coinage altogether. The fact is that original coins are preferred to cleaned examples.
How Does Tarnish Affect The Value Of Coins?
In the sense that toning and patina represent originality on a coin, tarnish—if we are to call it that in the context of numismatics—generally has a positive effect on value.
Most collectors expect older silver coins to have patina. This is the rather evenly distributed color that most older, circulated silver coins attain naturally over time.
Image source: Numista
Patina on silver coins normally ranges in color from light grey to dusky grey and even charcoal. There is often a slightly lighter shade of grey on the areas that are worn. Sometimes the greys melt into light golden colors. Patina often boasts highlight colors, such as hints of more vibrant colors or darker shades. That is toning.
Silver coins are usually worth less if they exhibit any of the following:
- black toning
- streaky coloration
- unusually mottled or speckled surfaces
- other unpleasant colors.
On the other hand, a silver coin with naturally vibrant toning will be worth much more. Uncirculated pieces with rainbow tones ranging from red or orange to violet can be worth exponentially more.
Of course, that is only the case when the toning has naturally appeared on the coin. Artificial toning is the act of intentionally subjecting a coin to conditions that rapidly accrue coloration onto the surface. This practice is considered “doctoring.” Coins that are doctored with artificial toning are usually very tough to sell. Most collectors don’t want coins that they view as altered in this fashion.
So, Tarnish On Coins Is Good?
In a word, yes. Again, we numismatists don’t usually refer to the colors on coins as tarnish, even if that’s what it is in the basic sense. Like so many things in the hobby, patina and toning are highly subjective in nature. Some like it more than others. But most collectors will agree that, on any given day, even a heavily toned coin is better than a cleaned coin. And toned coins will almost always be worth more and sell for more than a similar piece that has been cleaned.
The message here? Don’t clean your coins!
Joshua McMorrow-Hernandez is a journalist, editor, and blogger who has won multiple awards from the Numismatic Literary Guild. He has also authored numerous books, including works profiling the history of the United States Mint and United States coinage.
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