Silver-plated brass is a composite material made by applying a microscopic layer of silver onto a core object constructed of brass. This coating is typically achieved through an electroplating process, which fuses the silver to the base alloy. Silver-plated brass tarnishes just as solid silver does, and often more quickly. This discoloration is an inevitable chemical reaction, but understanding the material’s construction can help manage its appearance over time.
The Dual Vulnerability of Plated Metals
The primary mechanism for discoloration involves the silver surface reacting with compounds in the atmosphere. Tarnish is a form of corrosion that occurs when silver is exposed to sulfur-containing gasses, most notably hydrogen sulfide, which is present in trace amounts in the air, pollution, and even some foods. This reaction creates a layer of silver sulfide on the surface, resulting in a dull yellow, gray, or black appearance.
The plated nature of the item introduces a second, more complicated vulnerability. Silver plating is extremely thin, often only a few microns thick, and it is susceptible to being worn away by friction, cleaning, or general handling. Once the silver layer is breached, the underlying brass alloy, which is primarily copper and zinc, becomes exposed to the environment.
Brass is more chemically reactive than silver, and its exposure can accelerate the discoloration process. This base metal can react with moisture, salts, and air to form its own corrosion products, sometimes appearing as a greenish or reddish stain known as “brass bleed-through.” In the presence of an electrolyte like sweat, a localized galvanic corrosion cell can even form between the two dissimilar metals, causing the less noble brass to corrode preferentially and rapidly degrade the surrounding silver plating.
Extending the Life of Silver Plated Brass
Proactive care is the most effective way to slow the chemical reactions that lead to tarnishing. Since airborne sulfur is a major factor, proper storage is paramount. Storing pieces in an airtight container or zipper-lock plastic bag significantly limits their exposure to the atmosphere.
Placing anti-tarnish strips within the storage container can absorb sulfur and moisture vapor, providing an additional layer of protection. These small strips are designed to capture the reactive compounds before they can reach the metal surface. It is also helpful to keep silver-plated items away from materials that naturally emit sulfur, such as wool, rubber bands, and newsprint.
Mindful handling during wear can also prolong the life of the plating. The silver layer should not come into contact with cosmetic products like perfumes, hairspray, or lotions, as the chemicals in these products accelerate tarnishing. Removing jewelry before swimming, exercising, or performing household chores prevents exposure to corrosive liquids like chlorine and sweat. For long-term preservation, a professional clear lacquer or microcrystalline wax can be applied to create a physical barrier between the silver and the environment.
Removing Existing Tarnish
Tarnish removal requires a gentle approach because the thin silver layer can be easily damaged or entirely stripped away by abrasive action. Harsh commercial silver polishes are often too aggressive for plating and can quickly wear through to the brass core underneath. Instead, cleaning should begin with simple, non-abrasive methods.
A soft microfiber cloth and a mild solution of warm water mixed with a few drops of dish soap can be used to gently wipe away light tarnish and surface contaminants. It is important to dry the item immediately and completely with a clean, soft cloth to prevent water spots and moisture-accelerated tarnish from forming. Never use a stiff brush or abrasive sponge on plated items.
For heavier tarnish, a chemical reaction method is preferred over physical scrubbing. The electrolytic cleaning method involves placing the tarnished item in a container lined with aluminum foil, covering it with hot water, and dissolving a mixture of baking soda and salt into the solution. This process facilitates a reaction where the silver sulfide tarnish is chemically transferred from the silver surface to the aluminum foil, restoring the shine without mechanical abrasion. This non-destructive technique is highly effective for safely cleaning silver-plated items.