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INTRODUCTION
In 1994, Mr. Verne R. Walrafen published a comprehensive guide to identifying die varieties used in production of the Chihuahua EJÉRCITO CONSTITUCIONALISTA 5 and 10 centavos pieces of 1914 and 1915. Twelve obverse dies and 43 reverse dies were identified as having been used to produce 52 die varieties of 5 centavos, while one obverse die and four reverse dies produced four varieties of the 10 centavos. Mr. Walrafen’s sample contained “approximately 2,000 specimens” on which he based a rarity estimate for “Common”, “Scarce”,“Very Scarce”, “Rare” and “Extremely Rare” categories. |
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Collecting coins by die-variety can be tedious and frustrating. Having once attempted unsuccessfully to assemble a collection of 1851 U. S. Large Cents by die-variety, I was well aware of the difficulties and frustrations ahead, but decided to attempt to assemble a complete set of these historically important coins of the Mexican Revolution of 1910-1917.
As I started to acquire die variety examples, I began to research the why and how of their production. In many ways, this has been even more frustrating than assembling the collection.
ORIGIN OF THE COINAGE
In early 1914, General Francisco “Pancho” Villa, Governor of the State of Chihuahua by virtue of his having driven the Federal Army from the state, ordered the defunct branch mint of the central government’s Casa de Moneda in the city of Chihuahua reopened to produce coins in the name of the EJÉRCITO CONSTITUCIONALISTA in a 5 centavos denomination. The Chihuahua mint had ceased operation following the production year of 1895 after more than 60 years of service to the nation, turning out coins in copper, silver and gold. What equipment remained in the defunct mint is unknown, but it is quite likely that the very heavy and bulky equipment such as furnaces and rolling mills, and perhaps coining presses, were not removed. We can be fairly certain that General Villa intended to use the mint as it stood. Money was always in short supply, and expenditures for modernization and improvements to the old mint would have had a very low priority. We can assume that the mint equipment used was of late-19th Century vintage.
With the mint having closed 18 years before, it is likely that quite a few employees of the defunct facility still resided in Chihuahua and were available to return to work. New staff also had to be hired and trained, and their training period is attested by the numerous errors of production seen in the1914 pieces. By early 1915, it had been decided to add a 10 centavos denomination to the Chihuahua coins. Production continued until November 1915, when the villista government of the State of Chihuahua, was forcibly removed from power by the Constitutionalist Army of Primer Jefe Venustiano Carranza.
While the mint was being rehabilitated, the 5 centavos coinage was designed and preparation of dies begun. The obverse die was designed by J. Salazar, whose surname appears below the “cap and rays” device on the obverse of each coin. The reverse design was executed by Manuel Sevilla. When the 10 centavos coin was added in 1915, the 5 centavos obverse and reverse designs were used in a slightly enlarged format. The design elements of the 5 and 10 centavos coins are essentially consistent, although variations in size and shape of design elements indicate that each working die was prepared individually. The central design of the obverse was the “cap and rays” device used on Mexican coinage since the time of the establishment of the REPÚBLICA MEXICANA (1824). The central design element of the reverse dies was a “¢” symbol on which the denomination was superimposed. As with the obverse dies, there are numerous minor variations in execution of the design indicating that these dies were, also, prepared individually.
RAW MATERIALS
The composition of the coining alloy of the 5 and 10 centavos pieces is, presently, unknown. The vast majority of 5 and 10 centavos pieces appear to be “copper” coins, and are listed as such in the catalogs. Occasional examples of these coins are found with a yellowish, “brassy” appearance, and are cataloged separately as “off-metal” issues.
Most “copper” coins of the era were made of an alloy of copper, zinc, and tin (95% copper and 3-4% zinc and 1-2% tin). This alloy, a bronze due to its tin content, produced a durable “red copper” coin that toned over time to a dark brown. The use of tin in the alloy is not absolutely necessary to produce a “red copper” coin. A mixture of 95% copper and 5% zinc produces an alloy similar in appearance to the “red copper” coin and quite suitable for coinage. Decreasing the proportion of copper to zinc, whether intentional or accidental, increases the “yellowness” of the alloy. Alloys in which zinc exceeds about 15% show a yellowish or “brassy” hue.
Chihuahua had abundant resources of copper and zinc, and major refiners of both metals within its borders. Although tin was available from the neighboring state of Durango, disruptions in supply caused by continuing revolutionary activities in southern Chihuahua and throughout Durango may have made obtaining a consistent supply of tin impractical.
The occasional appearance of yellowish, or “brassy “ coins can easily be explained if the alloy was a “red brass” of copper and zinc. The “brassy” coins fall within various die-variety pairings, the majority of which also appear as “red” coins. There does not appear to have been an “official” change in the coining alloy. The “brassy” coins seem to have been the result of errors in preparing the raw materials for the alloy or in the process of melting and mixing the alloy.
The coins below, both examples of die pairing B:5, illustrate the difference in appearance of the “regular” coinage and that of “brass”. Note the lingering “red” component of the “brassy” coin. |
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X. Rare (Extremely Rare) - 1 to 2 surviving specimens known. Rare - 3 to 5 surviving specimens known. V. Scarce (Very Scarce) - 6 to 10 surviving specimens known. Scarce - 11 to 20 surviving specimens known. Common - 21 or more surviving specimens known. |
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“Regular” alloy |
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“Brass” alloy |
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This is an example of reverse die 3 in its “early die state” (EDS). The die itself exhibits no breaks, however, weakness in the strike of the legend at 1 to 4 o’clock, and the presence of debris at 4 o’clock indicates misalignment of the dies and a lack of cleanliness in the coining chamber. These deficiencies can, most likely, be attributed to inexperience on the part of the coining press operator. Both defects can lead to early die failure. |
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This is an example of reverse die 3 in its “terminal die state” (TDS). There are numerous breaks in the die, with marked “swelling” of the area from 1 to 6 o’clock. In most mints of the day, a die like this would have been removed from service as soon as one or more noticeable cracks had appeared. The Chihuahua mint seems to have followed the advice of my grandmother - “Use it up, wear it out, make it do, or do without.” |
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Obverse A of the terminal die state coin pictured above indicated that the obverse die has also failed. A bisecting crack runs from 12 to 5 o’clock. This die was removed from service at the end of the life of reverse 3, having been used with reverses 1 and 2 also. The longer life of obverse A seems to confirm that the obverse die was mounted in the “anvil” position. |
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PRODUCTION OF COINING ALLOY
I have not had examples of this coinage assayed to determine its composition. The cost of such assays would greatly exceed the value of my collection.
It is assumed that the melting and mixing furnace was one of the large items of equipment left behind when the mint closed. Copper and zinc (and, perhaps, tin) arrived at the mint in the form of billets or sheets from the several refiners in the state. Lots of the raw metals were prepared by weight, depending on the capacity of the melting and mixing furnace. For example, if the alloy was to be 95% copper to 5% zinc, a lot of 95 kilograms of copper and 5 kilograms of zinc would make a charge of 100 kilograms for the melting and mixing furnace.
The raw metals were loaded into the melting and mixing furnace in the foundry. The copper was loaded first and heated to its melting point. When the copper was completely melted, the zinc (and tin, if available) was added. The contents of the furnace were heated for an additional period, then poured into water-cooled molds to form alloy metal slabs called “cakes”. The cakes were allowed to cool to room temperature. Once the alloy cakes were cooled, they were broken out of the molds, ready for introduction into the rolling mills. An error in measuring the raw materials could result in a yellowish, “brassy” looking alloy. The number of melting and mixing furnaces, their capacity, and how they were fired is unknown. In the early 20th Century, both coal and natural gas were in use to fire furnaces in other mints.
PRODUCTION OF COIN BLANKS
A cake of coining alloy was re-heated in a furnace, fired by either coal or natural gas, where it to a point just below melting. The heated cake was fed into a rolling mill. The rolling mill, a series of steel rollers, extruded the hot alloy into a progressively thinner sheet. When the desired thickness was reached, the extruded sheet of alloy passed through a quenching chamber where it was sprayed with water and allowed to return to room temperature. The extrusion of the alloy in the rolling mill “work-hardened” the metal. The number of rolling mills and quenching chambers and their motive force is unknown. Most mints of the late 19th Century relied on steam power for their motive force.
Once cooled, the sheet of coining alloy was run through a milling and planing machine called a “scalper”, which mechanically scraped away the outer surfaces of the sheet producing a relatively clean and shiny strip of metal. The scalped sheet was sent through an annealing furnace, which heated the metal to about 1,400˚ F to soften or “relax” the “work hardening” produced by extrusion and scalping. The sheet was then fed into a finishing mill where it was rolled down to its specified thickness for introduction into the blanking press. At the finishing mill, the sheet was collected as either a coil of metal, or in individual sheets to be fed into the blanking press.
The blanking press was a gang-press with sets of smooth-faced dies which punched coining blanks of appropriate diameter from the coil or sheet. The diameter of the blanks was, intentionally, slightly less than the diameter of the steel collar in the coining chamber in which it would be struck. The punched-out blanks fell into a hopper for further processing, while the remains of the punched coil or sheet were removed and returned for re-processing into more coining stock.
The prepared blanks were sent to an upset mill, which consisted of a set of V-shaped dies through which the blanks were spun as they passed, raising a rim on the edge of the blank. The upset blanks were dumped into a polishing and pickling furnace. This device was a heated drum with internal baffles which rotated, tumbling and polishing the upset blanks. The pickling solution was designed to remove all traces of dirt, grease, ash, or other contaminants from the blanks. The blanks then went to a water bath to be completely rinsed and then to a drying oven. At the end of the drying cycle they were ready to go to the coining press.
PRODUCTION OF WORKING DIES
This stage of the production sequence occurred before, and during the acquisition and preparation of the coining alloy and blanking were in progress.
Using the designs provided by Sr.s Salazar and Sevilla, die makers would cut the central design into softened steel billets. As die cutting proceeded, the die would have to be returned to the annealing oven from time to time and heated to about 800° F. to relieve the hardening produced by cutting its surface. Once the central design elements were engraved, the legend, dates, and ornaments were applied “by eye” using single steel punches. It is in this process that we see the evidence that each die was prepared individually.
The finished die then went to a machine shop where its base was machined to fit the coining chamber of the die press, and the die face given a final polish. From the machine shop it was returned to the annealing oven, heated once again and then quenched in oil to harden it. The annealing process relaxed the “work hardening” of the steel, and the tempering process hardened the entire die to withstand the constant pounding it would face in the coining press. The finished dies were sent to the presses for production.
COINING
By the late 19th Century, hydraulic toggle-presses had been well developed and most were fitted with automatic feed and eject mechanisms which did away with the necessity for the operator to place each coin blank in the coining chamber by hand. The toggle presses of the era operated at a striking pressure of about 100 tons, and could produce about 100 coins per minute. The exact type or types of coining press available in the mint at the city of Chihuahua and their motive power are unknown.
The dies were mounted in the coining chamber. Traditionally, the obverse die was mounted in the lower portion, or anvil, of the press, and the reverse die was mounted above in the “hammer” position. A machined steel collar lined the coining chamber to prevent the blank from expanding laterally when struck. This collar was machined to the specified diameter desired in the finished coin, but was slightly larger than the blanks to prevent jamming. Careful alignment of the dies was essential to producing a fully-struck coin and to prevent the reverse, or hammer die from striking the steel collar and chipping or breaking.
The prepared blanks were placed in a hopper at the coining press, and a sliding mechanism picked-up a blank and carried it across to the coining chamber, depositing it atop the chamber, while ejecting the coin that had just been struck. The mechanism was quite dependable, but even so, required constant supervision to remedy jams and prevent the press from clashing the dies together when there was no blank between them.
At the beginning of the 20th Century, good die steel could produce obverse dies capable of sustaining 300,000 to 500,000 strikes before having to be replaced. This figure is based on the average die-life of the U. S. one cent dies of 1912 from the three U. S. mints (Philadelphia, Denver and San Francisco). Because the obverse die rested in the bottom of the coining chamber, or “anvil” position, endured three to five times the number of strikes as the reverse die placed in the “hammer” position of the coining chamber. Reverse dies statistically survived about 100,000 strikes each. These statistical averages are not applicable to individual dies, but to groups of dies. Some individual dies last through many more strikes than the average, while others fail far short of the average. It is obvious from the surviving specimens that the mint at Chihuahua used their dies far longer than most of the world mints of the era. Rather than replacing a reverse die when breaks began to appear, they were used until they were on the verge of disintegration.
Coin VRW-3 (A:3) offers a good example of the policy of the Chihuahua mint to get the most use out of their dies. |