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Corrosion

As the purity of the silver increases, the problem of corrosion or tarnishing lessens.

Chemically, silver is not very active — it does not react with oxygen or water at ordinary temperatures, so does not easily form a silver oxide. However, the other metal in the alloy, usually copper, may react with oxygen in the air.


The black silver sulfide (Ag2S) is among the most insoluble salts in aqueous solution, a property that is exploited for separating silver ions from other positive ions.

Tarnish

Tarnish is not a foreign substance above the surface of the silver. Rather, tarnish is sulfur which has become chemically bound into the surface of the silver. Scouring away the silver on the surface in order to remove the tarnish is extreme overkill. The only way to remove the sulfur without removing the silver surface is to (GENTLY) reverse the chemistry.

Keep in mind that there are two qualities you are trying to revive: 1) the original mirror surface formed by the silversmith during the final stages of production, and 2) the microscopic scratches which have naturally accumulated over that mirror surface in the course of lovingly using the piece. Abrasion during cleaning will obliterate one or both of these qualities, and thereby most of the value of the piece.

Hand Polishing: This is the method of care adhered to by serious collectors, as it brings out the beautiful luster of the sterling without destroying its patina. There are a variety of products available for hand polishing, from pastes to creams. It is generally best to stay with well-known silver-care product manufacturers, as some inferior products may cause scratching. (When in doubt, test the product in an inconspicuous area or on a less valuable piece.) Some examples are Twinkle Silver Cream (very gentle), Wright's Silver Cream (slightly more abrasive), and creams and pastes by the Hagerty company. These are readily available through supermarkets, jewelry stores and silver dealers, as well as on the Internet.

The author of this paragraph infinitely favors Hagerty's foam. Not the pink spray made by the same company, but rather the foam. Forget supermarkets. Look for it in department stores which have a wedding gift department. You'll find it in white plastic jars about the size of a baseball. Despite being called foam, it actually looks like chocolate pudding... and smells absolutely nothing like chocolate pudding. Use it as you used to use finger paint in kindergarten: with your bare fingertips, rub the foam over the surface of the silver. Keep running your fingertips back and forth until, usually after just a few seconds, you begin to see the spots of tarnish fade. In cases of more stubborn tarnish, you may need to rinse with tap water and again finger-paint with the foam a second or third time. Don't be impatient and reach for something scratchier to hurry up the process: that's the slippery slope towards destroying a piece.

Some pieces should not be immersed in water. Items containing mirrors, wooden parts, fabric, glue, etc. should be finger painted with as little foam as possible, then wiped with a barely damp sponge or cloth. For particularly small areas of silver near parts that must not become wet, a Q-Tip dabbed into the foam will usually do quite well.

Not all yellowness on a piece of silver comes from tarnish. Gold wash or vermeil was often applied to the interior of cups and goblets and on the service end of utensils to protect against corrosive beverages and foods. This wash is usually thin, and can be easily removed with too-abrasive or too-vigorous cleaning. Hagerty's foam will not injure gold wash, but aggressive burnishing with a cloth can injure it.

Keep in mind that it's not necessary or even desirable to remove every bit of tarnish from a piece of silver. Especially when the piece has fluted or embossed surfaces, it's expected that the deep grooves will acquire a darker hue than the raised areas. The resulting contrast is something to be left intact. Should a particularly stubborn spot of tarnish refuse to fade after, say, half a dozen foam finger paintings, it's time to leave well enough alone.

Crucially, avoid injuring any identifying mark which may be present on the piece. American pieces will, if 92.5% silver, have the word STERLING stamped on them, usually on the underside. Older American pieces, at 90% silver (called coin silver), may have nothing more than the maker's mark stamped on them. European pieces, of various percentages silver, will typically have anywhere from one to half a dozen cryptic symbols (lions, anchors, crowns, moons, faces in profile, single or double letters, etc.) hammered into them. It is imperative that these symbols not be worn away: they are the hallmarks by which a piece's age, origin place and maker are indicated. Lose the hallmarks and what had been a verifiable 1754 French hand worked masterpiece is now an unidentified could-have-been-mass-produced-last-week piece of junk.

If you are going to use the piece soon after applying the foam, finishing up the wash with gentle dishwashing liquid and lots of cool water is perfectly reasonable. It is also perfectly reasonable to eat from the piece immediately after rinsing just with water. If, however, you are going to put the piece away, let the foam be the last thing you rinse from the piece. A trace of the foam will remain even after you've run enough fresh water over it not to be able to see any more foam. This trace amount of foam will slow down the piece's chemical desire to become tarnished again. Don't put a piece away wet. Gently towel it dry (blotting rather than rubbing) and let it air for perhaps an hour before storing it away.

The remainder of this section is informative but should be shunned. Remember: you can play one of two roles with this piece... you can either be its protector, or its destroyer. Silver has value. If you feel that the radical steps described below must be taken, let it not be you who takes these steps. Instead, sell the piece as-is and get your money out of it before you render it worthless.

Wheel Polishing: In cases of extreme tarnish and/or corrosion, it may be necessary to take the item to a jeweler or silver repair company. There the tarnish can be removed with jeweler's rouge. This is sometimes referred to as putting an item "on the wheel". While this method does remove tarnish, it also removes the patina, or fine scratches which give antique silver its beautiful glow, leaving in its place the shiny look of stainless steel. Thus, this method is avoided by serious silver collectors in favor of hand polishing.

See and avoid. In almost every case I've encountered, people who own polishing wheels are obsessed with overusing them... even so called professionals. Jewelers are often called upon to remove a previous owner's initials from, say, a set of silver spoons. I have seen the results of overly enthusiastic jewelers who removed the initials by burnishing out a thumb-sized crater, thereby rendering the piece even less valuable than it had been with someone else's initials still attractively inscribed.

Silver Dips: There are now a great many silver dips and liquids available. THESE ARE AN ABOMINATION. They contain thiourea, and are the lazy man's method of ruining sterling. The item is dipped in the liquid, and within a few seconds it attains whiteness. This whiteness, however, is not caused by removal of the tarnish, but by chemical conversion of silver sulfide to a cloudy substance that is harder to remove than the original tarnish, necessitating yet another polishing with more abrasive substances.

Serious sterling collectors avoid silver dips. One reason is that silver dip tends to brighten areas of the design that should remain dark in order to give a relief effect. This is especially important in pieces that have Repoussé and chasing. Another reason is the difficulty in removing the end product of the conversion, which usually requires an abrasive cleanser.

Caveats: A few cautions should be noted. Sterling silver is a very soft metal that is easily damaged. Be careful not to dent the piece by knocking it against a sink or other hard surface. Be very gentle with sterling hinges, such as those on teapots and boxes, as these can be easily bent by mishandling. Do not use a toothbrush or other bristled brush on sterling, as this will permanently scratch the surface.

Frequency of Polishing / Storage: Sterling that is continuously on display, such as a tea service or candelabra, will need more frequent polishing than pieces that can be wrapped and stored. Much of this depends on the amount of sulfur in the environment (city dwellers living near high automobile traffic, for example). Simple sealable food storage bags, or dry cleaning bags for larger pieces, will inhibit tarnish from accumulating on stored pieces. Make sure that the item is thoroughly dry before storing, however, as trapped water will cause corrosion.

Several sources indicate that storage in plastic bags can do more harm than good, since poor quality plastic emits gases that cause corrosion and tarnish. Make sure you use a good quality polyethylene sealable food bag in conjunction with a silver cloth or acid free paper. This will provide good protection.