Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Fine silver (99.9% pure) is generally too soft for producing functional objects; therefore, the silver is usually alloyed with copper to give it strength but preserving the ductility and beauty of the precious metal. Other metals can replace the copper, usually with the intent to improve various properties of the basic sterling alloy such as reducing casting porosity, eliminating firescale, and increasing resistance to tarnish. These replacement metals include germanium, zinc and platinum, as well as a variety of other additives, including silicon and boron. A number of alloys, such as Argentium sterling silver have appeared in recent years, formulated to lessen firescale or to inhibit tarnish, and this has sparked heavy competition among the various manufacturers, who are rushing to make claims of having the best formulation. However, no one alloy has emerged to replace copper as the industry standard, and alloy development is a very active area
There is general agreement that the sterling alloy originated in continental Europe, and was being used for commerce as early as the 12th century in the area that is now northern Germany.
From about 1840 to somewhere around 1940 in the United States and Europe, sterling silver flatware became de rigueur when setting a proper table. In fact, there was a marked increase in the number of silver companies that emerged during that period.
The height of the silver craze was during the 50-year period from 1870 to 1920. Flatware lines during this period sometimes included up to 100 different types of pieces. In conjunction with this, the dinner went from three courses to sometimes ten or more. There was a soup course, a salad course, a fruit course, a cheese course, an antipasto course, a fish course, the main course and a pastry or dessert course.
Individual eating implements often included forks (dinner fork, place fork, salad fork, pastry fork, shrimp or cocktail fork), spoons (teaspoon, coffee spoon, demitasse spoon, bouillon spoon, gumbo soup spoon, iced tea spoon) and knives (dinner knife, place knife, butter spreader, fruit knife, cheese knife). This was especially true during the Victorian period, when etiquette dictated nothing should be touched with one’s fingers.
Serving pieces were often elaborately decorated and pierced and embellished with ivory, and could include any or all of the following: carving knife and fork, salad knife and fork, cold meat fork, punch ladle, soup ladle, gravy ladle, casserole serving spoon, berry spoon, lasagna server, macaroni server, asparagus server, cucumber server, tomato server, olive spoon, cheese scoop, fish knife and fork, pastry server, petit four server, cake knife, bon bon spoon, tiny salt spoon, sugar sifter or caster and crumb remover with brush.
Flatware sets were often accompanied by tea services, hot water pots, chocolate pots, trays and salvers, goblets, demitasse cups and saucers, liqueur cups, bouillon cups, egg cups, sterling plates, napkin rings, water and wine pitchers and coasters, candelabra and even elaborate centerpieces.
In fact, the craze with sterling even extended to business (sterling paper clips, mechanical pencils, letter openers, calling card boxes, cigarette cases), to the boudoir (sterling dresser trays, mirrors, hair and suit brushes, pill bottles, manicure sets, shoehorns, perfume bottles, powder bottles, hair clips) and even to children (cups, flatware, rattles, christening sets).
A number of factors converged to make sterling fall out of favor around the time of World War II. The cost of labor rose (sterling pieces were all still mostly hand made, with only the basics being done by machine). Only the wealthy could afford the large number of servants required for fancy dining with ten courses. And changes in aesthetics resulted in people desiring simpler dinnerware that was easier to clean.
Tarnishing and Corrosion
As the purity of the silver decreases, the problem of corrosion or tarnishing increases.
Chemically, silver is not very reactive—it does not react with oxygen or water at ordinary temperatures, so does not easily form a silver oxide. However, other metals 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.
Sodium chloride (NaCl) or common table salt is known to corrode silver-copper alloy, typically seen in silver salt shakers where corrosion appears around the holes in the top.
Several products have been developed for the purpose of polishing silver that serve to remove sulfur from the metal without damaging or warping it. Because harsh polishing and buffing can permanently damage and devalue a piece of antique silver, valuable items are typically hand-polished to preserve the unique patinas of older pieces. Techniques such as wheel polishing, which are typically performed by professional jewelers or silver repair companies, are reserved for extreme tarnish or corrosion.