Tarnish—the bane of the jeweler's bench. If you work with sterling silver, it's not a matter of "if" you'll encounter tarnish, but "when." Fortunately, you can help to safeguard your sterling jewelry and working stock by understanding the causes of tarnish: sulfur, moisture and sunlight. In this guide, you'll get an overview of what tarnish is, how to prevent its spread and some techniques for removing it once it's formed. Be proactive, and you'll protect your silver jewelry and your sterling reputation from tarnish.
Tarnished sterling silver presents a yellow-gold, brown or black film that masks silver's characteristic shine. Tarnished sterling looks bad on the surface—making what was bright and brilliant turn dull and dingy—but it won't cause significant physical damage the way that rust does to iron.
You can blame it all on sulfur, moisture and sunlight. When one or more of these agents comes in contact with the outermost layer of certain metals, it triggers a chemical reaction. The reaction leaves a thin, discolored layer on the surface of the metal. That's tarnish. (The copper that's present in sterling silver is highly reactive, which is why sterling is so quick to tarnish.)
Tarnish is a fact of life here on our sunny, watery planet. Sulfur occurs in small amounts in the atmosphere and in the air we breathe. It's even more concentrated, and more corrosive, in cities and industrial areas. The problem is that higher levels of exposure to sulfur, humidity or light make for the rapid spread of tarnish. Time is not on sterling's side, either: The longer that metal is exposed to these agents, even in relatively low amounts, the more tarnish that forms.
There is a fine line between tarnish, which is generally seen as a bad thing, and patina, which is generally seen as a good thing. How can you tell the difference? There are no hard and fast rules, but tarnish tends to be uneven, blotchy, brown and dirty-looking. Tarnish is sometimes referred to as a "chemical patina" because the metal's surface has been altered by a chemical reaction. Patina resulting from mechanical changes to the surface (also called "wear patina"), however, tends to be more uniform. It's a finish consisting of very fine marks, either developed over years of handling or created by jewelers to add contrast and depth to designs. And according to Jeff Herman of Herman Silver Restoration & Conservation, patina is your friend. It helps to conceal imperfections and firestain in jewelry and hollowware. In low-relief areas of a design, patina (or tarnish, for that matter) makes details pop. Whether you see it as tarnish or as patina, Jeff advocates for a less-is-more approach to cleaning pieces. "You're removing more than the tarnish, you're removing history," he says. "You're also removing precious metal, and that belongs to your customer!"
Minimizing contact with sulfur, moisture and sunlight are the keys to protecting any metal from tarnish. Light and moisture are relatively easy to spot, while the sources of sulfur can be more unexpected. The following lists point to common culprits to steer clear of, as well as best practices to follow.
First, check to see if your metal is dirty. Clean the piece with a little hand sanitizer rubbed on with a cotton swab, cotton ball or cotton makeup pad, or lightly sweep with a natural-bristle brush. (Watch Jeff Herman's "How to Polish Silver" to see how surprising and effective this preliminary step can be.)
If that doesn't take care of the discoloration, the Rio Grande Jewelry Tech Team find that a polishing cloth usually removes light tarnish. Sunshine® and Sunshine® Soft cloths, Selvyt® SC cloth, and Rich Glo® cloth and gloves are impregnated with micro-abrasives that gently lift tarnish.
For more advanced tarnish, lightly buff the affected areas with a gentle silver-polishing cream. We recommend Herman's Simply Clean™ Collectors Silver Polish and Blitz® Silver Shine Polish for their mild abrasives and non-toxic formulas, which can be applied with a wet cellulose sponge. Use a wet tampico or horsehair washout brush to remove any residual polishing compound on the piece.
If you work with mass finishing or cleaning equipment, some tarnish removing solutions can be added to those machines while they run. For example, Avalon Polishing Compound works while running your Avalon wet media tumbler, and SharperTek™ jewelry cleaning solution can be added to your ultrasonic machine (just be aware of any set gemstones that may be unsafe to clean ultrasonically).
Keep in mind that any polishing is a form of scratching. Always start with the mildest, least-abrasive method of cleaning or tarnishremoval to avoid damaging your metal. If you'd like to explore more techniques and topics concerning silver care, we highly recommend Jeffrey Herman's comprehensive and frequently updated webpage.