Silver & Sterling Silver
This article is about the chemical element. For the color, see Silver (color). For other uses, see Silver (disambiguation).
Periodic table: 47 Ag; Appearance: lustrous white metal
silver is a metallic chemical element with the chemical symbol Ag (Latin: argentum, from the Indo-European root *arg- for "grey" or "shining") and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.
Silver has long been valued as a precious metal, and it is used to make ornaments, jewelry, high-value tableware, utensils (hence the term silverware), and currency coins. Today, silver metal is also used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film, and dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides. While many medical antimicrobial uses of silver have been supplanted by antibiotics, further research into clinical potential continues.
Silver 1000 oz t (~31 kg) bullion bar
Silver is a very ductile, malleable (slightly harder than gold), monovalent coinage metal, with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost has prevented it from being widely used in place of copper for electrical purposes. Despite this, 13,540 tons were used in the electromagnets used for enriching uranium during World War II (mainly because of the wartime shortage of copper). An exception to this is in radio-frequency engineering, particularly at VHF and higher frequencies, where silver plating to improve electrical conductivity of parts, including wires, is widely employed. Another notable exception is in high-end audio cables, where manufacturers claim that scaling copper conductors by 6% achieves slightly better results.
Among metals, pure silver has the highest thermal conductivity (the nonmetal diamond and superfluid helium II are higher) and one of the highest optical reflectivities. (Aluminium slightly outdoes silver in parts of the visible spectrum, and silver is a poor reflector of ultraviolet light). Silver also has the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for their ability to record a latent image that can later be developed chemically. Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide, the latter forming a black layer of silver sulfide which can be cleaned off with dilute hydrochloric acid. The most common oxidation state of silver is +1 (for example, silver nitrate: AgNO3); in addition, +2 compounds (for example, silver(II) fluoride: AgF2) and the less common +3 compounds (for example, potassium tetrafluoroargentate: K[AgF4] ) are known.
Sterling silver is an alloy of silver containing 92.5% by mass of silver and 7.5% by mass 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 while 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.
In England the composition of sterling silver was subject to official assay at some date before 1158, during the reign of Henry II, but its purity was probably regulated from centuries earlier, in Saxon times. A piece of sterling silver dating from Henry II's reign was used as a standard in the Trial of the Pyx until it was deposited at the Royal Mint in 1843. It bears the royal stamp ENRI. REX("King Henry") but this was added later, in the reign of Henry III. The first legal definition of sterling silver appeared in 1275, when a statute of Edward I specified that 12 ounces of silver for coinage should contain 11 ounces 2¼ pennyweights of silver and 17¾ pennyweights of alloy.
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.
At first place it is used for a wide range of silver jewelry.
In addition to the uses of sterling silver mentioned above, there are some little known uses of sterling:
Evidence of silver and/or silver-alloy surgical and medical instruments has been found in civilizations as early as Ur, Hellenistic-era Egypt and Rome, and their use continued until largely replaced in Western countries in the mid to late 20th century by cheaper, disposable plastic items. Its natural malleability is an obvious physical advantage, but it also exhibits medically-specific utility, including the fact that it is naturally aseptic, and, in respect of modern medical practices, it is resistant to antiseptics, heat sterilisation and body fluids.
Due to sterling silver having a special sound character, some brasswind instrument manufacturers use 92.5% sterling silver as the material for making their instruments, including the flute and saxophone. For example, some leading saxophone manufactuers such as Selmer and Yanagisawa have crafted some of their saxophones from sterling silver, which they believe will make the instruments more resonant and colorful in timbre.
Tarnish 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.