How Silver Tarnishes

People will say that silver "turns color", "gets dark", or "oxidizes".  While these may all be general descriptions, they are not scientifically accurate.

Silver is a metal that has many unique properties:  It's lustrous and is attractive for jewelry, and it is soft and easy to bend and shape. It also is dramatically affected by air pollution, notably what are known as sulfides (sulphides).

When a car or lawn mower burns gasoline, or an electric plant burns coal, it generates air pollution such as sulfur dioxide.  This goes into the air and circulates everywhere.  Therefore if you live downwind of a power plant, or in an urban environment, then your silver will tarnish faster.

Silver tarnish forms in a fairly predictable manner.  When it begins to build, it starts out by making the white luster yellow.  This usually shows as golden-tinted splotches.  Then, a purplish-hue forms as a warning that action should be taken.  By the time the tarnish is black, it could be deeply embedded.  Silver has a grain structure as it is either cast or rolled in its manufacture.  Once tarnish sinks in between the microscopic-grain structure, damage can be done.

If you live in an area where the ground water is rich in magnesium sulfates (Epsom salts, for instance, sometimes known as Pluto water) be careful with your jewelry.  This soil will generate awful smelling fumes known as hydrogen sulfide.  Some well known places are French Lick, Indiana and Porterville, California.  While the salts have homeopathic and purgative properties, their vapors will tarnish silver quickly.

Eggs are rich in sulfides, and eating eggs with real silverware will almost always tarnish silver, sometimes irreparably.

Scientifically, the equation that demonstrates the reaction to form tarnish looks like this:

A recent paper (1) indicates that within 2 hours of exposure to heavy air pollution silver will lose its luster, in 4 hours it will show tarnish, in 10 hours it will be uniformly discolored, and in 24 hours it will be very tarnished.  Increased humidity, elevated temperatures, and air circulation will accelerate the effects and make the tarnish worse.  They also found that exposure to bright light (like sunlight) will also increase the speed which silver will tarnish.

When silver lightly tarnishes, clean it immediately.  What (sadly) happens so many times is that a silver item is tucked away in storage in a box, and many years later it's rediscovered.  By then, the tarnish has penetrated so deeply that the silver is permanently scarred.

Other Forms of Silver Discoloration

One unexpected and shocking occurrence is when someone goes swimming while wearing silver jewelry.  Silver will blacken upon exposure to chlorine.  Often this will require a jeweler's attention.  Even being near a swimming pool will blacken your silver!  The rule of thumb is if you can smell chlorine, your silver is already in danger of discoloring.

Obviously household bleach will do the same thing, so be careful.  If you have to use bleach in your house, cover up your silver.  The fumes will even seep through a kitchen drawer.

Don't wash your silverware in a dishwasher.  Dishwashing detergents can contain heavy chemicals which can either directly discolor silver, or interact in solution with the hot water and chemicals and other metals (aluminum, copper, or steel) to permanently discolor your silver.

Laying silverware on top of stainless steel, or natural steel utensils can cause a electrolytic reaction.  Over time, the conductivity of silver with humidity will cause rust on the steel, and that steel will migrate in and permanently stain or corrode your silverware. 

Exposure to silver dip.  Blitz does not recommend, make, or distribute any silver dip.  We believe it to be toxic, a poison in the household that could hurt children and pets, and is known (by California) to be a carcinogen.  However, if you choose to use it, be careful.  It can leave a film – sometimes a thick yellow film - on your silver after it removes the tarnish.  Blitz does have a non-toxic Silver Shine ™ (#681) product you can use with confidence.

http://www.blitzinc.net/product/681/Silver_Shine__Silver_Jewelry_Cleaner.html

Blitz has been making "the polish is in the cloth" since 1912.  All of our flannel silver polishing cloths are non-toxic, 100% cotton, made of the gentlest ingredients, and easy to use.  Use them any time that your silver shows a hint of tarnish, and they leave a barrier that resists re-tarnishing.

(1)  Tarnishing of silver in environments with sulphur contamination, by Chang Jiang Yang, School of Chemical Engineering, Dalian University of Technology, Dalian, China ; Xia Liu, School of Chemical Engineering, Dalian University of Technology, Dalian, China, 2007, pp: 21-26,  Copyright ©Emerald Group Publishing Limited: http://www.emeraldinsight.com/Insight/ViewContentServlet?Filename=Published/EmeraldFullTextArticle/Articles/1280540103.html#1280540103019.png