Coining (mint)
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A coin die (archaically spelt dye) is one of the two metallic pieces that are used to strike a coin, one per each side of the coin. A die contains an inverse version of the image to be struck on the coin. Striking a coin refers to pressing an image into the blank metal disc, or planchet, and is a term descended from the days when the dies were struck with hammers to deform the metal into the image of the dies.
Modern dies made out of hardened steel are capable of producing many hundreds of thousands of coins before they are retired and defaced. Scissel is the scrap produced in the punching of coin blanks from a continuous strip of metal.
Ancient coin dies
Prior to the modern era, coin dies were manufactured individually by hand by artisans known as engravers. In demanding times, such as the
Medieval coin dies
Medieval engravers were guild members who created coins.
The vast majority of medieval coins were cold struck; the planchets were not heated. While medieval coin dies were largely made of iron, some dies have been discovered with a small region at the face of the die which is made of steel. As technology and the economy changed over the course of the Middle Ages, so did the techniques used to create coin dies. While most ancient coin dies used engraving very heavily, early medieval coinage was dominated by dies created mostly from punches, which displace the metal of the die instead of removing it. There is evidence of medieval die cutters using engraving tools to lay out designs, and to create detailed punches. However, engraving on the face of the die did not become commonplace until the early Renaissance.
Very detailed records exist for the Venetian mint. Located in the heart of Venice, this mint served as a hub for commercial life and patronage at the time. In the late Middle Ages, the dies used to create tornesellos lasted as follows: "hammer" die, ~17,000 strikes; "anvil" die, 36,000 strikes. The mint made an average of 20,000 coins per day, so they were making one hammer die a day and one anvil die every other day. The "hammer" dies wore out quicker because they tended to be smaller and were hit directly with a hammer, leading to severe mushrooming on the tops. The Venetian Mint's most important coin was the Silver Grosso, a coin modeled after coins produced in the Byzantine Mint. It was from the Byzantium mint that the Venetian mint was modeled after. The decline of the Silver Grosso began under the rule of doge Andrea Dandolo in 1343. Her rain saw the rise of the Gold Ducat, almost eliminating the silver Grosso entirely.[4]
Modern die production
Note about spelling
In the time of Samuel Pepys in the 17th century, the spelling "dye" was used,[5] a spelling which persisted in some quarters to the 20th century.[6]
Production methods
First, an artist creates a large
When making working dies, the Mint[
If, when the die is subjected to another hubbing, it is not lined up exactly with the hub, the result is a secondary image, or doubling. This is called die doubling, and results in such spectacular coins as the famous 1955 doubled die cent.
The third side of the coin
On the edge of the US dime, quarter and half dollar, and many world coins there are ridges, similar to
Die marriage
During a typical production run, or coining process, (particularly when heavy presses are used for large production runs) a die is selected out of a group of several dies for the front and another die is selected from a different group of dies for the back of the coin to be made. The mint employee then places each die into the minting press for operation. When the run is complete, the dies are removed from the press. This procedure is repeated for each production run. Coins minted by each mint for each year may have several production runs in order to complete their orders.
If there is more than one die used for either the front or the back, then minute differences between each die can be identified. This is usually only for Early U.S. coins, as modern coin dies are made using computers, so unless there is an error coin die, all of the dies are identical. In addition, the relative positioning between the back and the front can also be used to determine which dies were used for the run that produced a particular coin. In the United States, coins are typically minted head to tail; that means the "top" of one side of the coin is on the exact opposite side of the coin as the "bottom" of the other, resulting in the coin's features being presented right side up when the coin is rotated on a horizontal axis. This is called a "coin turn" alignment. Correct alignment for a "coin turn" is exactly 180 degrees; however due to realities of machine process, this can vary by a fraction of a degree. In rare cases, this deviation can be up to several degrees, and very easily noticeable. However, even very small deviations can establish the production run in which a coin was minted. When this is done, it is called a die marriage. Die marriage is particularly important with regards to the US half dollar minted at the New Orleans Mint in 1861, since it establishes if a coin was minted with the mint facility under Union, State of Louisiana, or Confederacy control.
Use
In modern presses, a die strikes approximately 120 coins a minute. This rapid coining causes wear on the dies.
Mistakes can happen at any stage of this manufacturing process, and these mistakes are something that certain collectors look for. Coin errors that occur on the die are generally more desirable than errors made at the time of the strike. For example, a doubled die, where a date or another device appears twice slightly offset, is often a highly desired error. Strike errors are generally unique, whereas all coins struck with an error die will have the same characteristic. This makes them more easily collectible. The most famous doubled die in the past hundred years is the 1955 doubled die Lincoln cent. These trade for hundreds of dollars because the error can easily be seen by a casual observer. Many doubled die errors require at least a jeweler's loupe to be seen. Doubling can occur at the hub stage as well. Some more recent errors are hub doubled. Most famously, there is a 1995 doubled die cent that is hub doubled.
Terminal die state
The terminal die state, as the name would seem to indicate, is the last state in which any die is used. This is the state of a die that is starting to develop serious structural failures through cracks. A die in such a state would, if not removed from service, become unserviceable by breaking apart. Like any metallic part, dies are subject to failure from the enormous pressures used to impress the image of the die onto the blank planchet. Some dies were removed when even a microscopic defect is observed, while others were used until they literally broke into pieces. The Bass Foundation has a particularly noteworthy example of an 1806/4 Quarter Eagle ($2.50 gold US coin) in which a piece of the die has broken away, resulting in a heavy rim break over the "LI" in "LIBERTY" on the front.[7]
More typically, a terminal die state will result in crack-like structures appearing on the coin. A good example can be observed on an 1839 Liberty Seated Dime. A crack-like feature is clearly seen going through the date, the shield, and the second star.[8] This crack-like structure appears like material that is overlaid onto the surface of the coin; this is because the crack on the die allowed the planchet materiel to flow into it during stamping, just like a deliberate design feature. Some coins exhibit multiple crack-like features, indicating a die that is very close to the end of its serviceable life. Coins that do exhibit such features can be labeled as “Terminal Die State” examples.
Coin die represented in other coins
A coin die itself, has been the main motive for many collectors coins and medals. One of the most recent and famous one, is the Austrian
See also
- Mint (coin)
- Moneyer
External links
- Designing and minting coins The creation of a die and the minting process
- US Treasury: Preparation of Working Dies
- Collier's New Encyclopedia. 1921. .
Notes
- ^ The term "coining" is also used in metalworking. See coining (metalworking).
References
- ^ Hu, Di. "Experiments in Ancient Roman Coin Minting". Archived from the original on 2007-10-07.
- ^ a b Jere M. Wickens (1996). "The Production of Ancient Coins". Archived from the original on 2008-02-19. Retrieved 2009-08-20.
- ^ a b c Bean, Simon C (1994). "Methodology" (PDF). The coinage of Atrebates and Regni (Ph.D.). University of Nottingham. pp. 28–29. Archived (PDF) from the original on 10 September 2016. Retrieved 14 July 2016.
- ISSN 0078-2696.
- The Royal Mint. Archivedfrom the original on 2023-11-25. Retrieved 2023-11-25.
- ^ "The Percy Smith Medal". NZ Archaeological Association. 1975. Archived from the original on 25 November 2023. Retrieved 25 November 2023.
- ^ http://www.harrybassfoundation.org Archived 2015-03-28 at the Wayback Machine HBCC-3014
- ^ "Liberty Seated Dimes Varieties 1837 - 1891 - 1839_105cpage". Archived from the original on 2015-04-02. Retrieved 2015-04-01.