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[Conder101]

Before we get to the final process of coin creation, an important stage must be covered, called the die making process. Dies are what strike the coins and impress a design into the coin’s surface. This process starts out with an artist’s drawing which is then transferred by the artist into a large plastilene model (commercial modeling clay). The model is coated in graphite, which conducts electricity, and is lowered into a copper plating wash. This process attracts copper molecules to the designs surface. Eventually a thick copper layer forms and is a perfect representation of the design on the inside of the layer. This layer of copper is then filled with Plaster of Paris. When dry, the plaster is removed and is an exact replica of the plastilene model in the beginning. This 15 inch model is then placed on an antique pantograph machine, called The Janvier transfer-engraving machine to reduce the large engraving models to actual coin size onto the end of a bar of steel.

I think this is confusing two different processes. In the early years the original model was done in plaster not plastilene but in both cases that model was then used to create a negative mold in plaster. That negative mold was then coated with the graphite and then the copper was plated onto the negative mold to create a positive shell model of the design in copper. (Sometimes they alternated layers of copper and nickel.) This copper shell was known as a galvano and it was then backed with either plaster or metal to give it strength and is then used on the reducing machine. A plaster model is much too soft and would be damaged or destroyed by the tracing point. In more recent years they stopped using the metal plating and just used the negative of the original model to cast a positive in epoxy. The epoxy was strong enough to survive the reducing machine and much faster than the electroplating. Cheaper too.