Tarnish: The Dirtiest Word
Why Does Jewelry Tarnish?
Well, in one simple word--sulfur. Sulfur in the air interacts with metal to creating that dingy, and ultimately black, layer on your jewelry and the copper constituent is usually the culprit.
Copper, you say? Copper reacts with sulfur to create tarnish in the form of copper sulfides. Ever wonder what the stamp 925 on your silver jewelry actually means? Well, it designates it as sterling silver, but also the composition.
Sterling silver is 92.5% silver and 7.5% copper. Copper is added to increase the strength and durability of silver, which would otherwise be pretty soft and damage easily. Likewise, brass is an alloy of copper and zinc. And copper is, well, copper.
The surface layer of metal is where the corrosion or patina occurs. It can be made up of a variety of combinations:
- metal and sulfur, or sufides
- metal atoms plus oxygen, or oxides
- metal, sulfur, oxygen and hydrogen, or sulfates
- metal mixed variably with oxygen, carbon, sulfides and sulfates to form different salts
Some tarnish, or patina, is done on purpose. The specific combinations of copper and airborne molecules determine tarnish color. Common colors are green, blue, whitish, black, or red.
The rate of tarnishing can be exacerbated by humidity, and exposure to certain salts, acids, lotions, perfumes and house-hold cleaners (such as chlorine bleach).
So what are some methods to remove tarnish?
1. One of the simplest methods is to use a soft toothbrush, with mild soap and water to first remove dirt and oils. Then rinse, dry, and use a jewelry polishing cloth to buff to a beautiful shine. The polishing cloth already contains the "abrasive" to remove the tarnish. You simple rub your jewelry in the cloth, and voila!
2. Chemical Dip, I would recommend this mostly for cleaning chains, which can be a pain otherwise. The chemical dips usually contain thiorea, and sulphuric acid, and both are a bit nasty. Certainly follow the instructions and have good ventilation.
It's also very important not to let the jewelry sit in the liquid. A super quick dip is all you need. Prolonged exposure can cause pitting in the metal surface. If you do dip jewelry containing stones, be extra careful. Porous stones such as turquoise, pearls, opal, shell, etc. should not be dipped and can be damaged!
3. Steam Clean/Ultrasonic is usually reserved for professionals. An ultrasonic cleaner can be used to remove stubborn dirt or grime. By sending low frequency sound waves through a solution, the ultrasonic vibrates adhered particles off the metal surface. Steam cleaners (similar to espresso makers) shoot a stream of super hot steam, helping to dissolve adhered dirt.
To prevent tarnish, limit exposure to humidity, chemicals, and salts and clean your jewelry regularly. If you are storing your jewelry for any prolonged time, consider the following: store in a zip lock bag, an anti-tarnish bag or cloth, or in a closed jewelry box. Like many things, storing in a cool, dry spot will help prevent tarnish from forming in the first place.
Ziploc bags, while not attractive, will limit exposure to air and humidity. I find that storing jewelry in a closed jewelry box works pretty well. While not air sealed, the closed box prevent air from being widely circulated. There are also some jewelry cases and bags constructed of anti-tarnish materials.