суббота, 20 июля 2013 г.

Coining technology — part I. Ancient Greece to Late Roman Empire

 As well as thousands years ago, before becoming a coin a piece of metal has a long way to go – from a mine to master’s stamp.
Here on these pages we shall try to follow and illustrate the evolution of the process of coining in Europe from Hellenes masterpieces, through brackteates to large and nice testons and thalers.

 Coining technology has always been keeping up with human’s scientific and practical knowledge. Studying ancient coins and the technology of their production we can find out by the tree’s cutout, what the level of peoples’ knowledge on the metallurgy industry was. We can find out how the crafts were developed and try to understand the esthetic ideas of one region and time or another, try to find out the political and economic situation of that time.
The microscope and macro-photos can help to define almost all steps of converting a piece of metal into a coin on its surface. The masters of coining used their own special methods typical for that concrete period of time or place of coining.
Being acquainted with technological details of procedures of making ancient coins can help the beginner collector to avoid the moments, connected with buying the fake items.

 Archeologists and numismatists came to conclusion that the coins were invented as means of paying in the Mediterranean between 700-600 BC. Couple hundreds of years later coining became the basic way of producing coins there, but not the casting as it was earlier. These kinds of coins had a lot of advantages. They were more detailed, which was impossible to see during the process of casting. But the process of coining itself was so complicated that producing such coins without special equipment was impossible. The coining also became an additional “step of protection” from false-coiners of that period: false casted coin could be defined visually, by the empty sectors, by cavities from the air bubbles, by indistinct relief of the image and the lack of gloss that was a characteristic of original coin.
The coins in the 6th century BC were round pieces of metal with relief image. The technology of their production included the preparation of the planchet of a definite weight by casting in forms or cooling a drop of metal on a flat surface. After having done the needed quantity of planchets they went to coining. The stamps were made from bronze, which is a soft metal that is why their wear-out has gone out. That is how a great variety of stamp types explained. The master’s assistant warmed up the future coin in the oven and then put it to the lower stamp with the forceps to make the stamps last longer. Adjoining the upper stamp to the red-hot silver circle, the master made coining by a hammer strike. The working area of the upper stamp (square cross-section of the core) was not decorated at first, but looked like an abstract high-relief geometric sample, which enabled better heads coining by penetrating into metal.

 Lidia, Croesus (about 560-546 BC) 1/2 of stater.

   Gradually, the tail’s image became more complicated, squares and rectangles were changed into complex images; the letters, palmettes and images of plants appeared. The next step of tails decorating was placing the negative concave heads image of the coin. This type of coins is a characteristic of Greece colonies of Southern Italy.

Southern Italy, Metapontium in Lucania, nomos (520-510 BC)

   While coining technique development and artists’ and engravers’ skills improvement the image of tails became more and more complicated and turned into the candle-holder of the heads. Sides’ ranking was taken into consideration in the technology of coining as well: upper stamp (tails) wore out much faster, that is why supportive images were there, while the lower stamp (heads) contained the images of God or kings. Gradually, during the process of coining and further circulation, round coins with two-sided method of coining pushed out all other forms of currency. So, the coin got all the basic features and form, which has not almost changed until today.

Upper bronze stamp of the Athens tetra-drachm, which was found in Egypt, and the tails of the Athens silver coin of the 4th century BC

Prime days of the ancient coining art were in Classic and Hellenistic Greece from where the best masterpieces came. Regular coins of the Ancient Greece amaze with the highest level of artistic and technical performance.

DecadrachmorSyracuse (400-395 BC)

Greek’s technologies were kept and developed by ancient Romans. The mint at the Capitol Hill near Juno Coin Temple covered money needs of the significant territory of the Roman Empire by great mintages of dinars with emperors’ portraits and mottoes. As art species Roman coins are not as good as the best Hellenistic ones. But their achievement is in the creation of well-adjusted, almost industrial, technology of coining.
The coins become not only the means of paying but of promotion reflecting rapidly changing situation in the Empire. Every new Emperor wanted to state his own power by making coins with his name and portrait and his conquers at the tails of the coin.
Producing the work material for coins was the main technological trait of Roman dinars coining. Big issues and deadlines did not allow spending much time for singular unit production. That is why the metal was casted into forms that consisted of a row of cavities. Liquid metal was running over from one cavity to another and so on. After that work materials were cut and sent to coining. After some time this method was significantly improved. Silver bullion of a definite weight meant for coining was chaffed into flakes. Then, according to the required monetary unit, pure metal mixed with the alloys (copper more often), and the mixture spread into several heat-resistant forms with some cavities in them according to the coin sizes. Metal flakes were baked in the oven giving the entire work piece. That is why Roman dinars’ milled edge has such an uneven structure, which is a characteristic of the contracted elements. After that working pieces were plated with a hammer and went to coining. This method greatly reduced time for preparation of coin circles and saved masters’ efforts. As the metal for each coin was not weighed separately, the disadvantage of such method of coining was in the weight difference of dinars; but at the same time that gave the opportunity to control total material spending and the quantity of produced coins.


   Dinars coining was made by two stamps; the lower one was safely fastened in clutches, and the upper one was held by a hand and set while coining. High relief of the Roman coins, as well as Greek, was high, so for all the details to be well-coined, working material was preliminary made red-hot in the oven. Heated working material was less rigid, which helped iron and bronze stamps last longer.
Working materials and coining were basic technological operations while coining. But the most important process, defining the image of the future coin, was stamps production. The portrait was always placed at the working surface of the lower stamp, and at the butt-end of the upper one – the mirror-like image of the tails. This is not just a tradition, but the necessity, connected with the fact that the upper stamp worn out quicker than the lower one, and the heads’ image was more important and complicated.

 Emperor Maximinus’s dinar (235-238) and the iron stamps of the first centuries AC

   The engravers – scalptores monetae — were the ones to make stamps in Rome, and they formed specific corporation at the mint, which was headed by praepositus. After getting the sketch and the text of the legend of the future coin, the masters started to produce coining instrument. Two iron or bronze bars were used as stamp’s working materials. The lower stamp was shorter than the upper one for the reason of convenient holding by a hand. The butt-end of stamps was made even and then polished. After that fringe and legend marking was drawn on the working surface with the help of compasses. The base of the negative profile image was coined at the stamp with a previously prepared puncheon with the Emperor’s silhouette and head on it. Portrait details were coined on that base with the help of some smaller and simpler puncheons with a dotted, triangle, crescent or ring working edge. The nose, eyes, lips and hair appeared like that, until the image started to look complete. It is hard to believe, but while making such a realistic and live portrait, the master did not practically use the graver. When the portrait or other compositions were done, the master started to do the edge and the legend. Almost all Latin letters were coined with the help of several puncheons: long and short “I”, big and small “C” and “S”. When the image was done, the stamps were polished for the second time. Markings and metal leftovers, which were forced out with a puncheon while making the deeper image, vanished at the final stage. After hardening the stamp was ready for coining.
The use of puncheons did not just make stamp production easier, but also provided the unity of style, equality and awareness of Roman coins. As the upper stamp was optionally added to the working material during the process of coining, the majority of Roman coins have an uncombined interrelation of their heads and tails. But after linked stamp appearing there were coins with a strict sides’ interrelation in the late Empire times.

Linked stamp of Konstant I coin with Antiokhian mint letters, which was found in France, and bronze follis of this Emperor coined in Antiokhia

   Roman political and economic crisis was reflected in the money system come-down as well. The quantity of the pure silver of the basic coin of that period (silver dinar) was constantly reducing. So, by the end of the century the dinar had a fineness of 500.
At the beginning of the 3rd century the Emperor Karacalla started to issue the new coin, trying to save the money system of the Roman Empire and get the trust to the Roman coins back. It was named after the Emperor, whose full name was Mark Aurelius Antonin. Antoninian, by cost divisible into two dinars, first was a high-fined-five-grams silver coin. It differed from dinars visually as the second ones had a portrait of the Emperor in a laurel crown, and antoninians – in a crown. The appearing of this new coin has just temporary eased hard economic situation in the Roman Empire. But soon, due to the fact of money damage, the percentage of silver in antoninians became to decrease as well as in dinars before. By the end of the third century this coin became almost copper, and then was just slightly covered with silver. At the beginning of the 4th century Emperor Konstantin managed to set some stability in the money system by issuing new golden coin – solid. But let us not digress to the money systems of the Roman Empire from the main topic of the article – coining technique.

Vladimir Khomutov 

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