Yes, silver does turn black over time, a common phenomenon known as tarnishing. This dull, darkened layer is a thin surface film that forms naturally when the metal interacts with its environment. Tarnish is the result of a chemical reaction, not poor quality silver. Since this process is only a surface effect, it can be reversed to restore the silver’s original luster.
The Chemical Reaction Causing Tarnish
The black substance is silver sulfide (Ag2S), not rust or a simple reaction with oxygen. This compound forms when silver atoms react with sulfur-containing gases in the air, primarily hydrogen sulfide (H2S). This chemical transformation creates a dark, non-reflective coating on the metal’s surface. The silver sulfide layer initially appears pale yellow or brown, deepening to dark grey or black as the film thickens.
Environmental Factors That Accelerate Darkening
The rate at which silver darkens is heavily influenced by the concentration of sulfur compounds in the atmosphere. High humidity accelerates tarnishing because moisture facilitates the chemical interaction between silver and airborne sulfur. Air pollution, particularly in urban areas, increases the concentration of sulfur dioxide and hydrogen sulfide gases, which directly cause tarnish formation.
Many common household items and personal care products also speed up discoloration. Materials containing sulfur, such as wool, rubber, and latex, should be kept away from silver. Additionally, substances like chlorine bleach, ammonia, and sulfur-rich foods, including eggs, onions, and mustard, can quickly cause a reaction. Even natural oils and salts from human skin contribute to darkening, especially if the skin is more acidic.
Strategies for Preventing Silver Tarnish
Proactively managing the silver’s exposure to tarnishing agents slows the darkening process. Storing silver in an airtight container, such as a zip-top plastic bag or a jewelry box with a tight seal, reduces contact with sulfur gases. Placing anti-tarnish strips, silica gel packets, or a piece of chalk inside the container can absorb moisture and sulfur compounds, protecting the metal.
Wearing silver jewelry frequently helps prevent tarnish, as the friction and natural oils from your skin inhibit the chemical reaction. Put silver jewelry on last, after applying perfumes, hairspray, and lotions. Always remove it before swimming or using household cleaning products. Wiping pieces down with a soft cloth after wearing removes skin oils and residue, delaying discoloration.
Methods for Safe and Effective Tarnish Removal
Once tarnish has formed, there are two primary methods for safely restoring the silver’s shine.
Light Tarnish Removal
For light tarnish, a commercial silver polish applied with a soft cloth gently polishes away the thin layer of silver sulfide. A simple alternative is to create a paste using baking soda and water, rubbing it lightly over the surface, and then rinsing and drying thoroughly.
Heavy Tarnish Removal
For more heavily darkened items, an electrochemical reduction method using household materials is effective because it reverses the chemical reaction without removing any silver. This process requires lining a non-metal bowl with aluminum foil, shiny side up, and ensuring the silver object is in direct contact with the foil. Create a solution by adding a tablespoon of baking soda and optionally a teaspoon of salt to a cup of boiling water, then pour it over the silver to submerge it. The resulting chemical reaction transfers the sulfur atoms from the silver sulfide back to the aluminum foil, converting the tarnish back into metallic silver. After soaking for several minutes, rinse the silver in cool water and dry it with a soft cloth to reveal its restored brightness.