Silver tarnish is a natural surface discoloration resulting from a chemical reaction that affects the outermost layer of the metal, dulling its characteristic bright luster. Understanding what silver tarnish looks like helps determine if an item needs cleaning or if the damage is something else entirely, such as plating wear or corrosion.
Identifying the Visual Appearance
Tarnish follows a distinct visual progression. It begins as a light, hazy film, giving the metal a subtle, dull appearance, often manifesting as an iridescent sheen or a faint, yellowish tint. As the chemical reaction continues, the color deepens, progressing through brown tones to dark gray or bluish-black. The final stage of heavy tarnish is a deep, uniform black coating. This dark layer is a thin, chemically bonded compound that adheres tightly to the metal, often appearing first in recessed areas or along edges where air exposure is higher.
The Chemistry of Silver Tarnish
Silver tarnish is not rust, but a reaction with sulfur. Tarnish forms when silver comes into contact with sulfur-containing compounds in the atmosphere, such as hydrogen sulfide. This chemical interaction creates silver sulfide, a dark, non-metallic compound that causes the silver to lose its reflective shine. The rate of this process depends heavily on the surrounding environment. Common sources of sulfur that accelerate tarnishing include air pollution, certain foods like eggs and onions, and materials such as wool, latex, and rubber. High humidity and moisture also speed up the formation of the silver sulfide layer.
Confusing Tarnish with Other Metal Damage
It is important to distinguish true silver tarnish from other forms of metal degradation, as the necessary remedy differs. Genuine tarnish appears as a black, gray, or brown surface film that can be successfully removed. If the item is silver-plated, the thin layer of silver can wear away, exposing the base metal underneath. Plating wear typically appears as a patchy area of a different color, often yellow or pink/red, where the underlying brass or copper shows through. This is irreversible damage that cannot be polished away. Sterling silver, which is 92.5% silver and 7.5% copper, can sometimes display green or blue patches. This color, known as verdigris, is copper corrosion, not pure silver tarnish, and indicates a reaction of the alloy’s copper content.
Cleaning and Preventing Tarnish
To safely remove light tarnish, a gentle approach is recommended. Use a soft, treated polishing cloth or a mild silver cleaner. For light surface dullness, a simple wash with warm water and mild, fragrance-free soap is often sufficient to remove grime. For heavy tarnish, a non-abrasive chemical method, such as the aluminum foil and baking soda technique, can be used. This process converts the silver sulfide back into metallic silver. Prevention is achieved through proper storage, which minimizes exposure to air and moisture. Storing silver in airtight containers or bags with anti-tarnish strips significantly slows the tarnishing process. Also, avoid contact with household cleaning products, chlorine, and rubber bands, as these agents speed up the reaction.