Minting Technology

B09　—　Cross-cutting theme

The ridges on the edge of the coin in your hand.

Supervised by: Mitsuru Hayama　／　Reading time (main text): course text ~8 min + textbook ~31 min = ~39 min　／　Beyond the text: 10 exercises · 4 coins · 11 readings · 2 references

What this course teaches you to do

• You can tell striking from casting by the look of a finished coin.
• You can name three problems that milling solved.
• You can explain that changes in technique came from countermeasures against fraud.
• You can say why having many mints lowers quality.
• Can explain the three generations—hammer striking, screw press, and steam-powered machinery—along with the problems each solved.
• Can state the significance of a "perfect circle and edge" as a countermeasure against counterfeiting and clipping, from a technological perspective.

TEXTBOOK

Lessons (8)

1. To strike, or to pourStriking and casting are not better and worse but answers to different demands. Casting suits many small coins.
2. Three problems the machine solvedMilling was not for beauty but to spare people from checking. All three gains converge on fraud.
3. More mints, poorer qualityAs issuers multiply, the cost of oversight outruns the gain and quality must fall.
4. The worth of a standard that lastsHolding a standard steady is itself a craft: keeping unchanged what drifts if left alone.
5. The limits of the hammer — the frank compromise of the cobEven with their irregular shape, they circulated as long as their weight and fineness were correct. The cob is a physical embodiment of the idea that "a coin is stamped bullion."
6. Screw and Steam — What Machines Gave to CoinageThe screw press solved precision, and steam solved quantity. The two ounces of the Cartwheel are the weight of the Industrial Revolution.
7. The Art of Thinness — The Bracteate ParadoxImpressing with thinness rather than thickness. A unique technique of one-sided striking created a silver coin unlike any other.
8. The meaning of a perfect circle — when shape becomes trust.Perfect circles, uniform edges, and layered structures. The standardization of shape is not for aesthetics, but a technology to mass-produce trust by machine.

Case studies — applied in the materials (11)

• The machine and the revolution　Overview: 2,700 years of the world　the 17th century　The Milled Edge
  §2. The shortest statement of what the milled edge is for.
• The pillar dollar　Spain　1728 and 1730　Madrid
  §2. The scene of the decree moving from cob to milled coinage.
• More mints than kings　Spain　from 1454　Across Castile
  §3. Check in the original the statement that there were a hundred and fifty mints.
• Medina del Campo　Spain　from 1497　Medina del Campo
  §4. The story of a standard that did not change for a hundred and eighty-nine years.
• The silver of New Spain　Spain　the 16th–17th centuries　The workshop of a New World mint
  Section 5. "Coin is stamped bullion." The original text on the concept of money in the age of hammered coinage.
• Minting by steam　Britain　1797　The Soho Manufactory
  Section 6. Exactly two ounces. The precision and quantity that steam brought to coinage.
• The bracteate　Germany　the 12th–13th centuries　The territories of Saxony and Thuringia
  Section 7. A sheet of silver as thin as paper. A description of the technique of uniface striking.
• The pillar dollar　Spain　1767–1773　The Potosí mint
  Section 8. Deformed silver returns to the furnace. A scene from the end of the age of hand-striking.
• The silver of the colonies　Italy　the 6th century BC　Sybaris and Metapontum
  This is a technique where the design embossed in relief on the obverse is struck as a matching incuse depression on the reverse. Please read about both the difficulty of aligning the two dies without slippage and the fact that the reason for striking them this way has not been determined.
• Until the hole became square　China　the 4th–3rd centuries BC　A casting workshop
  The hole in cash coins changed from round to square not for ideological reasons, but for the convenience of filing. A square rod could hold dozens of coins fixed together, whereas with a round hole they would spin—a workshop convenience that determined a design for two millennia.
• Melt and Restrike　India　17th century　A Mughal mint
  Two countries that received the same Mexican eight-reales coins took different approaches: one counterstamped them for circulation, while the other melted them down and recoined them into its own currency. It is also written that only a country that could afford a mint, fuel, and labor could choose the path of recoinage.

Assessment

10 exercises in this course (7 check, 0 compare, 3 written). Progress is recorded by self-assessment.

References

• A study on the manufacturing method of the ancient coins, Sangpyeong Tongbo in Korea — npj Heritage Science（2025）　Example of quantitative analysis of composition and manufacturing methods (peer-reviewed journal).
• The Royal Mint Story — The Royal Mint Museum　History of the Royal Mint. Changes in production sites and technology from the Tower of London era to the present day.

Only works and primary sources whose existence has been verified are listed.