Contraposition. The matching opposite polarity; that is, a mirror image. A design with a figure facing right is said to be in contraposition to the same image facing left. One

of the advantages of the modern pantograph (including the Janvier reducing machine) is its ability to cut a die in contraposition to its model. Of course, all lettering in addition to all detail reverses polarity, and such lettering is termed retrograde lettering. Such unwanted change in polarity would have to be remodeled – a new model would have to be prepared with acceptable lettering.

How a die is cut in contraposition. On the die-engraving pantograph the pattern is set to rotate in the normal clockwise manner. The cutting is done in a die block that is set to rotate not in its normal manner, but to rotate in a counterclockwise manner. This will result in the design being engraved in the die block in mirror image.

In addition to the Pasteur example shown in the adjacent illustrations, another example of contraposition in modern medals is the 1920 Manila Mint Medal whose reverse is in contraposition to the same design on the reverse of the Assay Commission Medal of 1882.

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Medals In Contraposition

In 1922 the French medallist Georges Henri Prud'homme

created the portrait plaquette of Louis Pasteur shown on

the right above. It was struck by the Paris Mint. In 1958

the Pasteur Club of Cleveland wanted to honor their idol

by issuing a Pasteur Medal for a member recognition

program. They wished to utilize Prud'homme's portrait of

Pasteur. They asked Medallic Art Company to reproduce

the portrait from the 1922 medal and to add new, more

appropriate lettering.

The technicians at Medallic Art enlarged the portrait

from the medal and flipped it, by making Pasteur face the

opposite direction. This was done on the Janvier pantograph

which can enlarge as well as reduce – in addition to

cutting the new design in contraposition to the model!

They cut this enlargement in beeswax, gave the

beeswax model to Ramon Gordils, the staff sculptor.

He removed the old lettering and modeled the desired

lettering on the wax model, then made a plaster cast of this.

He had to touch up the wax and the plaster (to sharpen

the edges of relief), a usual step for any enlarging or

casting. A dieshell was made from the plaster, and the

dieshell placed on the Janvier pantograph again, this

time cutting a new die in normal manner.

While this sounds involved, it was done quickly, and

at less cost than remodeling a new portrait. In addition

it saved and reproduced a fine medallic portrait by a

famous French artist.