Annealing: The heat treating (softening) of metal after it has been work-hardened with steel tools, and is necessary between raising and forging stages. Annealing is also used to remove tension in a piece of metal before brazing, helping to reduce warpage.

Argentium Sterling: A new firestain-free alloy with great tarnish resistance. It contains the mandatory 92.5% fine silver and is indeed sterling.

Assay: It is impractical for a refiner to refine each individual shipment of scrap separately. To keep the operation efficient, a sample is taken of each refining shipment to determine its precious metal content. Drilling samples are taken from each end of the bullion. The assay laboratory does a miniature refining process on the two samples to determine the precious content. The bullion karat is actually determined by the percentage of fine gold left following the assaying process. For example, 2-100 milligram samples are taken. The samples are wrapped in lead, placed onto cupels and put into a special assay furnace. As the samples become molten, the base metals, including the lead, vaporize or absorb into the cupels, leaving only the precious metal on top. The precious metal buttons are dissolved in the acid so that the gold content can be determined. The remaining samples are reweighed. If the 100 milligram samples now weigh only 50 milligrams, this means that there is 50% fine gold in the bullion.

Brazing: This form of soldering utilizes high temperature alloys to join high temperature metals. When brazing sterling, care must be used to prevent firescale or firestain which is formed at higher temperatures than soldering.

Chasing:The technique of detailing the front surface of a metal article by indenting with various hammer-struck punches without cutting edges.

Checking: The hammering down onto the edge of a form. This technique strengthens and visually thickens the edge.

Coin Silver: Sterling is 925/1000 parts pure silver and is a legally enforceable standard. Coin is more variable; the purity of metal matching, in theory, that of contemporary currency. Occasionally, during periods of shortage, coins were literally used as metal stock, especially in the colonial era. Because of the multiplicity of coinage in use, it has varied from 835/1000 to 925/1000. It was never an enforceable standard like sterling, but was a means for silversmiths, lacking a national standard of assay, to assure clients of the quality of their silver. By the 1820s, with flat-rolled silver stock readily available, it became an arbitrary benchmark set at 900/1000 and remained so until the British sterling standard was adopted by Gorham, Tiffany, and others in the 1850s.

Conservation: Primarily dealing with cleaning an object, doing the least amount of harm to its original finish.

Crimping: A rapid raising process by forming radiating valleys from the center to the outer edge of a metal object then raised. Generally used on thinner gauge metal.

Cross-Peen Hammer: Hammers with long, narrow faces running perpendicular to the handle and used for raising, forming, and planishing.

Die Forming: The process of stamping or hammering a sheet of metal into a form which has the outline of the object. Also used when making duplicate objects.

Drawbench: A narrow, waist-high bench equipped with a chain dragging a pair of drawtongs (large coarse-toothed pliers) used to grip the end of a piece of wire. This wire is then pulled through a series of consecutively smaller dies (round, square, triangular, etc.) reducing its thickness. Patterned dies may also be used to produce moldings, boarders, etc.

Electroplating: The process of putting a metallic coating on a metal or other conducting surface by using an electric current. It is used to improve the appearance of materials, for protection against corrosion, and to make plates for printing.

The article to be plated is thoroughly cleaned of grease and dirt by dipping it in acid and alkaline cleaning solutions. It is then put in a solution of the metal with which it is to be coated. The metal exists in the form of positive ions (atoms that have lost one or more electrons). The article is connected to the cathode (negative end of a source of electricity). The anode (positive electric terminal) is connected to another conductor which is also dipped into the solution. The electric current acts on the metallic ions in the solution. The ions are attracted to the cathode, and the coating is deposited on the article's metal surface. If the metal in the solution and the metal of the positive terminal are the same, the electricity may remove metal from the terminal to replace metal taken from the solution.

The thickness of the layer deposited on the article depends on the strength of the electric current, the concentration of metallic ions, and the length of time the article has been in the solution. The terms triple-plated and quadruple-plated indicate various thicknesses of plating, not separate layers deposited on the surface.

Ornamental and protective platings are very thin, usually from 1/1,000 to 2/1,000 of an inch (0.03 to 0.05 millimeter) thick. For plating gold, silver, copper, zinc, and cadmium, cyanide solutions of the same metals are often used. Copper and zinc may also be plated by acid-sulfate solutions. Chromium is plated with a chromic-acid solution and nickel is plated with nickel sulfate. Other metals plated for commercial use include platinum, lead, and tin. Alloys of two or more metals may be deposited by using a solution of salts of the metals that make up the alloy. Examples of alloys used for plating are brass, black nickel, lead-tin, and bronze.

Electroplating is also used to reproduce medals or other objects in a process called electroforming. This process was formerly known as galvanoplasty. One kind of electroforming, called electrotyping, is the reproduction of type forms and engravings for the printing industry.

Resource: Melvin Bernstein, "Electroplating," Discovery Channel School, original content provided by World Book Online, http://www.discoveryschool.com/homeworkhelp/worldbook/atozscience/e/177500.html, 11/15/2001

Engraving: The process of cutting shallow lines into metal with a sharp graver, reproducing artwork which has been drawn on a metal article. Unlike machine engraving, hand engraving removes metal when cutting. Bright cutting is another form of engraving which when viewed is very reflective because of its flat, angled cut.

EPNS: Electro Plated Nickel Silver.

Etching: A process of dissolving metal with acid, leaving a recessed design. The upper, unetched surface is sometimes engraved.

Firescale: A scale that developes on the outer surface of a non-ferrous objects without protective flux during brazing. The scale must then be removed chemically or by abrasive methods.

Firestain: A purple stain that develops in sterling when oxygen penetrates the outer surface of an object during brazing, oxidizing the copper content. Fine silver is left on the surface when sulfuric acid chemically removes the oxidized copper, though copper may be oxidized below the surface. Colonial pieces will show this purple stain after many years of polishing.

Fold Forming: Fold forming is a new, quick, easily learned way of shaping sheet metal with hand tools. Forms are derived from the natural plasticity and ductility of the metal. Lewton-Brain invented fold-forming, which is internationally recognized as a new way to work metal. Shaping is extremely efficient and rapid (many take 3-7 minutes working time). Tools are simple: fingers, hammers, anvil, and mill. Complex relief forms are made from sheets of metal often on one annealing. They resemble chased, constructed, and soldered forms, and can be made with most metals, including steel.

Fused Plate: Excerpted and edited from Sheffield Plate: Its History, Manufacture and Art by Bertie Wyllie (London, 1908). Sheffield plate [fused plate] is the name applied to a variety of articles of domestic use or ornament, made of copper coated with silver by a special and now abandoned process. Many of them were actually manufactured in Birmingham, but as the secret of producing the material was discovered and brought to perfection in Sheffield, the name of that town was naturally connected with it, and thence transferred to articles constructed from it.

In 1742 a workman named Thomas Bolsover was mending the handle of a knife made of silver and copper, when, accidentally overheating it, he caused the metals to fuse and flow, and found that as a consequence the silver adhered to the copper as a thin coating. Being an intelligent man, he perceived the commercial value of his chance discovery, and began the manufacture of articles which, with all the appearance of silver, were both cheaper and stronger than those made of the pure metal. He apparently, however, confined himself to applying the silver direct to the surface of the copper after the latter had been given the shape destined to it, and was thus limited to the production of small articles such as snuffboxes, knife handles, toilet articles, etc. It was reserved to Joseph Hancock to realize that by making the plate first and working it into the desired form afterwards he could almost indefinitely extend the possibilities of the material.

The process in its final and highest development was as follows. The groundwork was a mixture of copper and brass, either metal alone having serious defects. This was cast into an oblong ingot, one to 12 inches in thickness, 21 inches in breadth, and of a length regulated by the size of the plate desired. The surface of this was brought by planing, grinding and other means to the highest possible pitch of smoothness and evenness. A sheet of silver of a finer quality than standard, with a thickness up to one inch according to the quality aimed at, and of the same superficial extent as the copper bar, was leveled and polished in the same way and accurately fitted to it, neither surface at any time being soiled by contact with the workman's fingers. A sheet of copper, rather smaller than the other two and in. thick was laid upon the silver, and on the top of all was added a piece of iron, four inches thick, one inch wide, and a little shorter than the three others, to protect them from the direct contact of the strong iron wire with which all were firmly bound together. The junction of the edges of the silver and copper blend was treated with a flux of borax and the whole was submitted to the heat of a furnace until the silver was seen to be melting, when it was instantly removed, care being taken to avoid pressing upon the upper or lower surfaces, as the liquid silver in that case would have been squeezed out from between the two enclosing plates and the operation ruined. It was then left to cool, and after being thoroughly cleansed presented the appearance of a copper ingot with one silver side. This was passed again and again between gradually approximated rollers, with occasional annealing, until the desired thickness had been attained. The great extension of surface thus produced had the drawback of exaggerating any small defect in the union of the two metals, increasing it to a blister of an inch or more in diameter. It was, however, fortunately found easy to remedy this. The blister if unbroken was heated, pricked, and then rubbed level with a burnisher; if, as sometimes happened, the silver had flaked away it was replaced by coatings of pure leaf silver rubbed in with a burnisher. The plate when passed as flawless was cut into the desired form and molded as far as possible into shape, the edges where necessary being soldered. At first only one surface of the copper was plated with silver and thus its usefulness was necessarily restricted, but it was a simple matter to apply the silver to both sides and thenceforward whatever was made in solid metal could be reproduced in plate, and firm after firm went into the business, ever and anon introducing further improvements.

The possibility of embossing the metal beyond a certain point without fracturing the coating of silver was remedied by casting or stamping the raised ornament in silver, filling the hollows with a form of pewter, and soldering the result to the appropriate part of the general design. Another difficulty, the concealment of the inner core of copper which was seen as a thin red line when a cut edge was exposed, was met about 1784 by George Cadman, who adopted the practice of soldering on an edging, generally ornamented, of solid silver so as to cover the junction, and the presence of this is one of the trustworthy tests by which genuine Sheffield plate may be recognized. The labor of rolling the metal by hand was done away with about 1760, by the firm of Tudor, Leader & Sherburn, who first employed horse-power, and for more than half a century the trade both in Sheffield and Birmingham continued to flourish. In 1736 there were under 10,000 inhabitants in the former city; in 1760 when Horace Walpole passed through it, buying for two guineas a pair of candlesticks of the local plate, which he thought "quite pretty," and pronouncing it to be "one of the foulest towns in England," there were two-and-twenty thousand who remitted eleven thousand pounds a week to London.

It would be impossible, were it desirable, to enumerate all the varieties of the articles turned out, or to overpraise the beauty and elegance of most of them. The designs were identical with those in favor with the gold and silversmiths of the period, which was happily one when exceptionally good taste prevailed. The appreciation of light and well-proportioned curves and the skilful employment of well-contrived pierced work are conspicuous features.

The success was, however, doomed to be short lived and to come to an end as swiftly as it had grown up. In the year 1800 W. Cruikshank was already experimenting with a process of electro-plating, and in 1837 Mr. Spencer in England, and in 1838 Professor M. H. Jacobi (1801-1874) in Russia, working independently, succeeded in contriving methods which could be made commercially profitable. Two years later Messrs Elkington in London and M. de Ruolz of Paris started in business on those lines, and the slower and consequently more costly manufacture at Sheffield and Birmingham rapidly died out.

Of recent years old Sheffield plate after long neglect has come into fashion again, and genuine articles in good condition have greatly gone up in value, often exceeding in cost those of more modern date in sterling silver. Concurrently fraudulent imitation has regrettably increased. In some cases the whole object is a modern reproduction in electro-plate, but more often really old articles from which the original plating has been worn off in course of time have been replated, both equally being in the eyes of the connoisseur, unworthy of serious attention and comparatively valueless. The difference after a little experience is not difficult to detect, though inexpressible in words. The pressure to which the Sheffield plate was submitted produces a definite color and texture which is absent from the surface produced by the deposit of silver in a liquid medium by electrical means, and the coat of silver is spread by the latter uniformly over the whole surface without a break, while in the former the junction between the embossed ornaments and the silver strips covering the cut edges may often be detected on careful examination.

Gilt: Gold plating over the entire surface of a silver (not silverplated) object. Objects that are partially goldplated are called parcel gilt (or partially gilt).

Hallmark: A mark or series of marks stamped or laser-engraved by a country's assay office indicating the quality of the precious metal tested (e.g., "Sterling," ".925," ".840," ".800," or an image of a "rampant lion"—indicating sterling as used in Great Britian). The object may also contain the country, assay office, maker's mark, housemark, duty mark, etc.

Head: A short, polished, cast metal mushroom-type stake that fits into a horse and is used for planishing and burnishing metal objects over.

Horse: Held in a vise, this straight or L-shaped holding devise accommodates heads. The length of a horse varies depending on the size or depth of the piece being fashioned.

House Mark: A mark stamped or laser-engraved by the company (e.g., "Gorham," "Reed & Barton," "Tiffany," "Kalo") that created the object for its own line or for a retailer (e.g., "Shreve, Crump & Low," "J.E. Caldwell Co."). In addition, there may  also be a maker's mark, indicating the company's craftsman who created or oversaw the creation of the object.

Maker's Mark: The name or artistic mark stamped, engraved, or laser-engraved on an object created by an individual silversmith or jeweler.

Mokume-Gane: Laminated metals that have been fused or brazed together like a sandwich, and passed through a flat or wire-forming rolling mill to make the material easier to fabricate or raise. The sandwich or "billet" can also be forged without the use of the rolling mill. Patterns are then punched, filed, and hammered to produce a desired pattern.

Patina: Patina can mean three things: 1. The fine scratches on an object that have developed over time from handling and polishing, 2. The natural darkening that is seen in the recesses of ornamental pieces and engraving, 3. A factory-applied chemical used to darken the recesses of a design to enhance its details and give it a three-dimensional look.

Patinate / Repatinate: To apply or reapply a chemical to darken the recesses on ornamental pieces and engraving that had naturally developed over time. This process is sometimes applied to objects that have had their darkening removed from dishwashers or chemical strippers such as Tarnex.

Planishing: The act of hammering or refining the surface of a metal object with highly polished hammer faces. This process refines the surface after raising and may be used as a decorative element. Great care must be used, for even a speck of dust will make an impression in the metal being hammered.

Polishing: The process of refining a metal surface by use of abrasive compounds applied by hand or a polishing wheel attached to a long-spindled motorized arbor which runs at high speed. Various finishes may be obtained with a wide variety of abrasive compounds applied to the polishing wheels such as rouge–this compound imparts the brightest finish. More abrasive compounds will produce less reflective finishes, emphasizing the object's form.

Preservation: To stabolize an object from further deterioration. This may entail using an archival wax to maintain the surface finish.

Raising: The technique of forming a flat sheet of metal over a cast iron T-stake or head, forming and compressing the metal to take a hollow form. This labor-intensive process is the purest form of silversmithing.

Refinish: To make an object look new by removing all scratches and imperfections.

Repair: To fix (best possible outcome) a damaged or worn area on an object.

Restoration: To either make an object or damaged area on that object look new, or to make it look its age without any noticeable damage or repairs.

Restore: To repair and finish an object to its original condition.

Repatinate: See Patinate.

Repoussé: A process used to roughly emboss a metal object with ornament from the back or inside with larger punches than those used in chasing.

Rolling Mill: A hand or motor-driven cast iron mill with polished or patterned hardened steel rollers that reduce the thickness or impart a texture on metal sheet or wire. Functions like a hand cranked clothes ringer.

Scratch Brush: A long-spindled motorized arbor using fine wire wheels rotating at slow speed, burnishing the surface of a metal object after soldering. Soapy water is used as a lubricant between the wheel and object. May also be used as a texturing wheel to soften the luster of metal.

Sheffield Plate: See Fused Plate

Silver
I. Introduction
Silver, symbol Ag, white, lustrous metallic element that conducts heat and electricity better than any other metal. Silver is one of the transition elements of the periodic table. The atomic number of silver is 47.

Silver has been known and valued as an ornamental and coinage metal since ancient times. Silver mines in Asia Minor were probably worked before 2500BC. The alchemists called the metal Luna or Diana after the goddess of the moon and ascribed to it the symbol of a crescent moon.

II. Properties
With the exception of gold, silver is the most malleable and ductile of all metals. Its hardness ranges between 2.5 and 2.7; it is harder than gold but softer than copper. Silver melts at about 962° C (about 1764° F), boils at about 2212° C (about 4014° F), and has a specific gravity of 10.5. The atomic weight of silver is 107.868.

Chemically silver is not very active. It is insoluble in dilute acids and in alkalies but dissolves in concentrated nitric or sulfuric acid, and it does not react with oxygen or water at ordinary temperatures. Sulfur and sulfides attack silver, and tarnishing is caused by the formation of silver sulfide on the surface of the metal. Eggs, which contain a considerable quantity of sulfur as a constituent of protein, tarnish silver extremely quickly. Small amounts of sulfide, which occurs naturally in the atmosphere and which, as hydrogen sulfide (H2S), is added to natural gas used domestically, tarnish silver. The black silver sulfide (AG 2S) is among the most insoluble salts in aqueous solution, a property that is exploited for separating silver ions from other positive ions.

III. Occurrence
Silver ranks about 66th among elements in natural abundance in crustal rocks. It occurs in the pure state to a small extent; the most notable deposits of native silver are in Peru and Norway, where the mines have been worked for centuries. Pure silver is also found associated with pure gold in the form of an alloy known as electrum, and considerable amounts are recovered in the processing of gold. Silver is usually found combined with other elements (of which sulfur is the most predominant) in minerals and ores. Some of the important silver minerals are cerargyrite (or horn silver), pyrargyrite, sylvanite, and argentite. Silver also occurs as a constituent of lead, copper, and zinc ores, and half the world production of silver is obtained as a by-product in the processing of such ores. Practically all the silver produced in Europe is obtained from the lead sulfide ore, galena. In the United States relatively few mines are worked for their silver alone—the silver is mined in conjunction with lead, copper, and zinc. In 1988, U.S. mines produced an estimated 53 million troy oz. of silver, about 12 percent of the estimated 444 million troy oz. produced worldwide. Most of the silver mined in the world comes from Mexico, Peru, Canada, the United States, and Australia. The leading silver-producing states in the United States are Nevada, Idaho, Montana, and Arizona; they accounted for about 71 percent of the silver mined in the United States in 1989.

IV. Metallurgy

Silver is usually recovered from silver ores by roasting the ore in a furnace to convert the sulfides to sulfates and then chemically precipitating metallic silver. Several metallurgical processes are used to extract silver from ores of other metals. In the amalgamation process, liquid mercury, which forms an amalgam with the silver, is added to the crushed ore. After the amalgam is washed out of the ore the mercury is removed by distillation, leaving metallic silver. In lixiviation methods the silver is dissolved in a solution of a salt, usually sodium cyanide, after which metallic silver is precipitated by bringing the solution in contact with metallic zinc or aluminum. For the Parkes process, which is used extensively in separating silver from copper and lead ores, see Lead. The impure silver obtained in the metallurgical processes is usually refined by electrolytic methods or by cupellation, a process that involves removing impurities by vaporization or absorption.

V. Uses

The use of silver in jewelry, tableware, and as coinage is well known. The metal is usually alloyed with small amounts of other metals to make it harder and more durable. In the United States, coin silver was an alloy of 90 percent silver and 10 percent copper until 1965, when the silver content was reduced to 40 percent for half dollars; silver was eliminated from dimes and quarters after 1964. In 1970 the U.S. government sold the last of its marketable silver, which in earlier periods of U.S. economic history had been used to support a monetary system of bimetallism. Sterling silver for tableware and other solid-silver objects is 92.5 percent silver and 7.5 percent copper. Silver is used to coat smooth glass surfaces for mirrors by vaporization of the metal or by precipitation from a solution; however, aluminum has largely replaced silver in this application. Silver is also widely used in the circuitry of electrical and electronic components. Colloidal silver, dilute solutions of silver nitrate (AgNO3), and some insoluble compounds, such as potassium, are used in medicine as antiseptics and bactericides. Argyrol, a silver-protein compound, is a local antiseptic for the eyes, ears, nose, and throat.

The silver-halide salts—silver bromide, silver chloride, and silver iodide—which darken on exposure to light, are used in emulsions for photographic plates, film, and paper. The salts are soluble in sodium thiosulfate, which is the compound used in the photographic fixing process.

Contributed By: Seymour Z. Lewin, M.S., Ph.D., Professor of Chemistry, New York University.
"Silver," Microsoft® Encarta® Online Encyclopedia 2000
http://encarta.msn.com © 1997-2000 Microsoft Corporation. All rights reserved.

Silversmith: One who fashions silver objects and wrought items such as forged flatware. The first silversmiths who settled in this country set up our banking system and produced its first coinage.

Sinking: The hammering of a flat piece of metal into a concave hemispherical shape in the top of a tree stump or any dished form. A small bowl shape is formed in the center of the sheet producing a lip, enabling the piece to "ride" the end of a raising stake, aiding in the raising process.

Snarling: The embossing from underneath or inside an object with a long-armed steel tool, with one end placed in a vise. Snarling is accomplished by placing a form over the snarling iron's tip (which may be any shape) and tapping the back end of the arm which is secured in the vise. The vertical vibration that results gives a "kick," raising a bump on the outside of the object. This technique is usually used in conjunction with chasing.

Soldering: A low-temperature form of brazing. This technique is used for joining low-temperature base metals such as pewter and does not possess the strength of brazing solders when joining higher temperature metals such as silver.

Spinning: Spinning, a technique that originated in the early 19th century, can be used for most metals. A metal disk is set on a lathe behind an appropriately shaped metal or wooden chuck, and during rotation the metal is pressed onto the chuck with long-handled, polished steel tools.. Britannia metal was often spun; a typical, modern spun object is the aluminum saucepan. As in most metalworking techniques, the metal is periodically softened by annealing, or heating, when it has become hardened through being worked.

Spring Hammer: A 5' cast iron beam supporting a long-handled, highly-polished pivoting hammer with a 3" diameter face. The hammer is mounted on a spring mechanism allowing the hammer head to bounce off a highly polished adjustable anvil used to flatten the bottoms of trays and anything else that requires a perfectly flat surface. The spring hammer head bounces off the anvil perfectly flat, avoiding a costly crescent-shaped miss-hit of a hand-held hammer head's edge.

Stake: Any polished cast iron or steel tool placed in a vise and is used for forming and planishing metal over. This tool is generally large enough to be used without a horse.

Sterling Silver: An alloy of fine silver (92.5%) and copper (7.5%) most commonly used when fashioning holloware and flatware because of its strength. Fine silver (99.99% pure) is generally too soft when producing large functional objects. U.S. law states that all objects marked "sterling," "925" or "925/1000" MUST contain no less than 92.5% fine silver.

Surface Gauge: A vertical steel rod mounted with an adjustable arm fastened to a heavy base. The adjustable scribe-type pivoting arm can be raised or lowered to check the height or to scribe a level line around an object in order to mount a wire or anything else that must be level. Often used on top of a surface plate.

Surface Plate: A perfectly level steel, cast iron or granite table of any dimension; used to check the level and flatness of an object. Often used in conjunction with the surface gauge.

T-Stake: Any polished, cast iron or steel tool in the form of an elongated "T" and used in a vise for raising, forming or planishing metal.

Vermeil: See Gilt