VOCABULARY TERM: FORMULATION

Formulation. Mixing of metals to form the exact alloy for a coinage composition. The procedure to prepare metal to be rolled into strip, blanked and struck into coins or medals consists of three steps: learning the exact composition of metal to be used, weighing the metal and adding to it the proper metal to meet the standards of the coinage alloy. The makeup of the melt must be the exact COMPOSITION for the intended coins. Medal compositions for bronze medals can be for more liberal (see Bronze chart).Preparing the proper composition is done by weight to make the ALLOY the correct percent of each metal.

Metal arrives at mints in many forms: melted coins, salvaged metal, virgin metal, BULLION ingots from various suppliers. Precious metal is tested (ASSAYED) to ascertain its composition and purity, then weighted and mixed with other metal before being melted together. Coinage laws spell out the STANDARD of silver compositions. It is seldom that a pure metal is ever used for coins (aluminum being an exception, but even this is often alloyed with manganese). Pure metal seldom has the wearing qualities required for a circulating coin.

Typically, gold and silver is alloyed with copper. Nickel (being very hard to strike in pure state) is also alloyed with copper to form copper nickel. For a bronze composition, copper is alloyed with zinc (formerly with tin and zinc). Thus most all coinage compositions are alloys. Formulation is the mixing of the metal – in pure state or already alloyed – to reach the required combination of metal components.

As an example, when Great Britain was on the STERLING standard of .925 silver, the formula was 37 fortieths of silver to copper. Nine parts of copper had to be added to 111 parts of silver to make the proper coin composition of .925.

Salvaged metal can be in many forms. A large quantity is SKELETON SCRAP from blanking (long strips cabbaged into a size for melting in furnaces). This is ideal since it is already of proper formula. But scrap or salvaged metal can be in sheet, bar, tube, wire, pellet or any fabricated form.

Brass shell casings from World War II were salvaged for American bronze coinage metal in the years following that war. Likewise cannons have provided salvaged metal after previous wars. (The Paris Mint made note of salvaged Russian iron canons make into several of their coining presses.)

Silver has been scraped from tableware, receptacles and silver objects of all kinds. Coinage silver, as another example, was made from melted firemen's horns from the Diligent Fire Engine Company #10 at the Philadelphia Mint in 1871 according to numismatic writer Walter Breen. Thus the source or physical form of metal is immaterial.

All scrap metal must be tested for purity, the function of assaying for precious metals, then formulated into the standard composition required for coinage strip to be used by a mint for coins. Such a strict metal standard is generally not a requirement for medals, typically struck in bronze or silver. Thus medals can be struck in bronze of most any formulation (see BRONZE chart) or silver of prescribed fineness from commercial metal suppliers.

After formulation (in a mint's melt shop), the alloyed mixture, called a charge, is melted in furnaces, agitated into one homogeneous mass. It is treated with flux, then poured into ingot molds and allowed to cool. The bullion at this point may have physical imperfections, however a chemical imperfection – an inhomogenous mixture – is serious, as it may continue to exist throughout rolling, blanking and even in struck pieces.

Incorrectly formulated bullion alloy is called BULLION BLUNDER. This occurs when an incorrect amount of metal was added during the makeup of the melt. Other than a possible discoloration of alloy, this anomaly is usually not evident but may only be determined by LABORATORY TESTING. Also the several metals may not have blended correctly to form a homogeneous alloy. See INHOMOGENEITY.

Reference: NC8 {1988} Breen.
CLASS 06.1

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