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Author: Admin | 2025-04-28
HomeFleur-de-coin.comMintingBi-metallics How bimetallic coins are made The basic idea of bi-metallic coins is not a new one. What is considered by many as one of the earliest strikings of bi-metallic prototypes dates back to 1730, when a silver token with a center copper plug was struck in Cologne, Germany, although the English Rose Farthing 1625-1649, during the reign of Charles I, had a brass wedge inserted into the copper as an anti-forgery device. Throughout the 19th and 20th Centuries many tokens and medallions have been struck by various countries, but the first bi-metallic coin to be widely used in modern times was the 500 Lira issued by the Italian government in 1982. Today, more than 117 countries have issued bi-metallic coins and the number is growing. These coins are minted in many different combinations of precious and base metals: yellow and white gold, gold and silver, silver and titanium, silver and nickel, non-magnetic stainless steel and aluminium bronze, and combinations of copper or brass and nickel, etc. The big worry when these coins were introduced was that they would fall apart in use, but that hasn't happened. Hundreds of millions of them are in circulation around the world, and that problem just has not occurred. There are very few mint errors of missing rings or missing centers, such as the first year of the Canadian polar bear two-dollar coins which made the front page in World Coin News. Coatings and Plating Copper-plated coins copper plated steel - eg Euro 1,2 and 5 cents (2002-) brass plated steel - eg West Germany 5 pfennig (1950-95), and 10 pfennig (1950-95) An early method of producing bimetallic coins was to put a coating of one metal onto a core of another metal. This was often done to disguise a debased coinage, eg by using a copper core and "silver dipping" it. Rome first issued the antoninianus as a silver coin of 2 denarii, but only worth 1½ denarii. This coin was gradually debased and reached its lowest during the reign of Gallienus (253-68) when it was a copper coin with a thin silver coating which quickly wore off. This was possibly achieved by dipping the copper blanks in a silver nitrate solution so that some of the surface copper would be electrolysed and go into solution and silver metal would be deposited on the blank. The later silver coins of Henry VIII of England were gradually debased until the last issue (1544-47) "silver" coins were struck from an alloy of one part silver and two parts copper (ie .333 fine). To make these coins appear to contain more silver than they actually did, the blanks were probably either silver washed (as above) or they may have been soaked in a weak acid solution to dissolve some of the surface copper. However, with wear from circulation, the richer silver surface was worn away, particularly on the high spots such as the king's nose, and this led to his nickname of "old copper nose". A
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