Blanks and the workshop
On Tsarevets, on the terrace west of the so-called Baldwin's Tower, excavators found the remains of copper working: slag, pieces of hammered copper sheet and unstruck, slightly dished blanks that match the Bulgarian imitations of type C from the early 13th century in shape, weight and metal. The spot stayed a craftsmen's quarter into the 14th century. The mass copper imitations of that time were made from hammered sheet: the earliest were cut with shears into many-sided pieces, the later ones punched out and struck in a single blow with a die-punch. That is why many are cracked at the edge or carry a small tag where the blank was snapped off by hand. None of the Tarnovo imitations was cast. Several of Ivan Shishman's cup-shaped copper coins from Tarnovo carry traces of silvering that got onto them by accident. This shows that the billon and the copper coins were struck in one and the same workshop of the Tarnovo mint.
Cup-shaped and flat coins
After Alexios I Komnenos reformed the coinage in 1092, Byzantine gold, electrum and billon coins were cup-shaped, slightly dished like a saucer (scyphate); only the small copper tetarteron stayed flat. The restored Bulgarian kingdom took over this system and until the end of the 13th century struck and used only cup-shaped coins. The first flat Bulgarian coin is George I Terter's silver. From Theodore Svetoslav onwards Tarnovo's silver was flat, while copper went on being struck in both shapes for a long time: under Ivan Shishman the cup-shaped and the flat copper coins carry the same designs.
Dies, and how many coins were struck
Every coin was struck between two engraved dies, one for each face. When hardly any two of several hundred coins found share a die, there were many dies and the output was large. Dochev uses this to gauge the Tarnovo mint: among 458 copper coins of Constantine Asen he found only a few matching die pairs, which points to 2–3 million coins; for George I Terter, 5 matching obverse pairs and 1 reverse suggest 150–200 thousand; for the silver of Ivan Alexander with Michael Asen, 790 coins with a handful of repeats suggest several million coins in 1337–1355.
The engravers
An engraver's hand gives away who struck a coin, and where. The Bulgarian imitations of the early 13th century show the work of Greek craftsmen who had cut the dies for the real coins of Alexios III. Ivan Asen II's two issues are in the fine Thessalonian style and were probably struck at Thessalonica. Constantine Asen's mint founded a Tarnovo school of engraving whose manner can be recognised for a century. That is why George Terter's silver, made by others, stands out so clearly, while Michael Shishman's silver horseman and Theodore Svetoslav's copper of variant B look like the work of the same hands.
Coins counted by the pound
Tarnovo's silver coins were not weighed one by one. A set number of coins was cut from a set amount of metal, the Byzantine pound (litra) of about 327 g, without checking that each coin met the theoretical weight. So coins of one issue vary, and the standard shows only in the average. When the treasury decided to get more coins out of a pound, every coin got lighter, which is how the silver coin lost more than half its weight in the 14th century.
Marks that date an issue
The silver of Ivan Alexander with Michael Asen was struck for nearly 40 years, and its issues differ in small marks. The first, around 1337, has a carefully cut monogram of the epithet 'faithful' and an inverted monogram of the title 'tsar'; the next and largest issue shortens the epithet to two letters. After Michael Asen's death the title monogram is written the normal way round, and the lightest late coins replace the monograms with clusters of three dots or little stars, sometimes with Ivan Shishman's monogram. The marks move in step with the weight, so they date the hoards too.
Overstriking
When metal ran short an old coin served as the blank: a new die was struck on it, and the earlier design sometimes shows underneath. For the numismatist this is a gift, because an overstrike shows which type is older. That is how Dochev orders Constantine Asen's types and dates the small Latin imitations of series A-H into the 1240s. Overstriking also made a political point: Tarnovo has a coin combining the types of Constantine Asen and his rival Mitso; Ivan Shishman overstruck Ivan Sratsimir's copper with his own monogram, and one was even pierced through the middle to put it out of use; Andronikos III overstruck the tornesi of the despot of Epirus after bringing Epirus under him in 1335. Overstrikes also tell of shortage: Ivan Alexander's first silver was struck on coins of Michael Shishman, and 15 of Ivan Shishman's flat coppers on other rulers' coins.
Clipping and cutting
A coin worth more than the new standard was brought into line with shears. Around 1195–1204 the Byzantine treasury clipped the older, heavier billon coins; in the Strelbishteto hoard 667 of 4356 coins are cut down to 18–22 mm. In Bulgaria from the 1220s heavy foreign coins were clipped to the state's standard: in Tarnovo over 90% of the large coins in circulation before 1257 are clipped or cut up. In the 1240s and 1250s cutting coins into halves, thirds and eighths simply aimed at more coins, until the pieces were too small to serve as money. The same happened on a smaller scale to Constantine Asen's coins in the early 1270s, to George Terter's copper and to Ivan Shishman's billon in the mid-1380s.
Control and melting down
The state watched what circulated in the capital. Copies of the reigning tsar's coins do not occur, only of older issues, and not a single imitation of an Ivan Shishman coin has turned up in Tarnovo. On the southern slope of Tsarevets two lumps of half-melted 14th-century imitations were found, individual coins still visible on one of them. Dochev reads them as confiscated forgeries handed in for melting, their metal going to the official coinage. The control did not suffice: when genuine coin was short, the people of Tarnovo kept using the banned imitations.
How the coins were made
Most of what we know about the Tarnovo mint comes from the coins themselves: their shape, the marks of the dies, the overstrikes and the clipped edges.
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