13 The Minting Process

1. The Idea 

A commemorative coin or medallion begins with an idea, or rather two complementary ideas, one for each side of the final coin. The idea forms the first step and becomes the basis for the artwork. Some ideas begin with something obvious, such as a coin that commemorates the anniversary of a significant event that has ready-to-use symbols, or perhaps may be patterned after an existing department badge or emblem.

Other times a somewhat vague concept must be fleshed out and given form. Pictures, sketches, clippings or emblems can all be used. Northwest Territorial Mint can also be consulted for existing artwork that they can utilize. Once the concept is been determined, the mint artist begins preparing the artwork.

2. The Artwork

In the past, the artist prepared the artwork exclusively by hand with paper and pencil. Today, the computer is frequently used as well. Changing the art at this phase is still relatively easy. Changing it after the die has been made would require a costly redoing of the art, the sculpt and the die.

The graphic designers who create coin sculpt art must be talented in many phases of art. The ability to draw intricate machinery as well as excellent human forms is required daily. Clearly communicated ideas along with customer sketches both help the artist develop what the customer has in mind. Material that can be referenced for coin artwork such as photos, patches or other illustrations, can be very helpful. 

3. Choice of Dies

Once a coin design sketch is finalized, determining the method of creating a die comes next. (If a stock die was chosen, then neither the artwork creation nor die creation steps were needed.) The nature of the coin design will usually determine the decision.

The least costly way to create a new custom die is through a titanium plate etching and engraving process described in step 5. Northwest Territorial Mint charges no sculpt fee for this process, but it comes with limitations in the detail and depth of relief achievable.

For artwork with fine detail or high relief, a sculpt will be required from which a precision die can be created. Sculpt creation is described further in step 4, and requires highly skilled artisans, for which a fee is charged.

4. The Sculpt

A sculptor takes the finished artwork then renders the design in relief. Sculpting is the essence of the engravers’ art.

The sculptor is a finely trained artisan who interprets flat, two-dimensional artwork and working with small sculpting tools on clay, renders a three dimensional sculpt that will form the basis of the coin relief.

In this stage the design takes on life and depth and in an enlarged form at up to 4 times the size of the finished coin, and done in clay, in a negative of the finished coin. Finally, a plaster mixture is used to create a positive plaster model of the coin from the clay original. The die maker now handles the next steps. 


5. The Sculpt in Titanium 

An alternative to the plaster sculpt already described, is one done on a titanium plate. In this method, a pattern of the artwork is etched onto the plate surface, then an artisan sculpts out the plate. While not suitable for high-relief, three dimensional coins, this method works well for coins with text or flat designs.

When complete, the sculpted plate is mounted into a panagram in which the die is then engraved from the plate by way of a stylus which mechanically reduces and engraves the pattern into the die.

6. The Die 

The die maker takes the plaster impression and prepares an epoxy cast, a negative, from which the die will be engraved. The epoxy model is mounted on a machine called a transfer-engraver. This machine uses a stylus to trace the epoxy model. The machine then reduces and transfers the design to a carbide tool that cuts that design into a blank steel die. Finally, any minor imperfections in the die are removed before the die is heat treated.

Heat treatment is a separate step from die creation and must be done to exacting specification. Only a Rockwell hardness scale of 58 to 60 is acceptable to reach the ideal hardness. A die that is too hard will be brittle and prone to cracking or breaking. Too soft and it wears prematurely. Now that the die has been readied, let us look at the steps of obtaining the coin blanks to be minted.

7. The Metals

The minting process uses a wide variety of metals or alloys. The precious metals used typically are available in bars of .999 purity. Alloys such as brass, cooper nickel, or the metal copper come in coils of metal ready to blank.

Blanking is the process of producing coin blanks which will then be minted. If the source material comes in bars, it must be reformed into a ribbon of metal suitable for blanking. Such bars are first melted down in a furnace and then ladled into cylindrical containers called billets. The billets are put through an extruder which forces the metal or alloy through a rectangular port creating a long ribbon of malleable metal. 


8. Blanking

Coin blanks are created by a mechanical cookie cutter working on a ribbon of metal that has been rolled down to the precise thickness required for the coin specifications. The blanking press then punches out blank discs of metal to be used for minting the coins.

From the blanking press, the blanks (also called planchets) receive a meticulous cleaning followed by polishing. Blanks destined for proof coins will receive a mirror like polish prior to the strike.

9. The Strike 

The strike is where the die finally “strikes” the blank. In the coining press the blank is impressed between the two dies with variable pressure that typically reaches several hundred pounds per square inch. Both the pressure and duration of each strike are controlled to match the metal type and characteristics desired for a given coin.

The top and bottom dies are locked into place. The press of the dies on the blank within the collar forces the metal to mold into the recesses of the die and to form the shape of the finished medallion. The number of strikes a given coin will receive is likewise determined by the material used and finish desired in the coin.

10. The Edge

The finish of the edge is determined by the choice of collar used in the coining press. When the die presses both sides of the coin, the coin metal is forced out causing the edge of the coin to conform to any pattern on the collar. The edge can be ridged or smooth or ridged with smooth sections.

Sometimes an additional step is done to provide engraving of a commemorative slogan or special dedication, or perhaps a sequential number. Such markings further enhance and distinguish each medallion minted.

11. Finishing

The appearance of the final coin will depend on the metal used and any treatment done to it after minting. Colors of the coin can vary considerably through choice of source metal though most will range from silver white to gold and bronze colors.

The coin may be finished just as it comes out of the press, but sometimes other looks are desired. The coin can have a mirror finish or treated to obtain an antiqued finish. Specialized enameling artists can hand-paint each coin into a colorful and unique original. Northwest Territorial Mint has also developed proprietary techniques in the process of applying 24K gold-plate on selected areas of silver medallions, an option called “Gold Select”.


12. Presentation and  Display

The presentation and display of your coin or medallion should reflect the importance of the coin itself. A variety of packaging options are available for finished medallions. Each can be sealed in a clear Lucite protective capsule and can be encased in a plush lined leatherette display box complete with your emblem or seal printed in gold on the box lid.

For a museum-like presentation, the coin or medallion can be embedded in a Lucite form which allows examination of both sides of the coin within a free standing form. Many shapes are available, call for which one works best for your display.

01 Numismatist’s Vision

02 Monetary systems ofcountries
03 Anatomy of a coin
04 Coin definitions
05 To clean or not toclean
06 Coinage metals
07 Elements and Alloysused for Coins Minting :
08 Cameo coins
09 Commemorative Coins
10 Fifty StateCommemorative Quarter Folder
11 Louis Braille Coins  
12 Manufacture of Coins
13 The Minting Process
14 Selected coins
15 World Mints_FamousCoins
16 Euro Coins andspecifications
17 Coins Bilbliography