NNP

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.                                     

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators

COMPILED AND WRITTEN BY D. WAYNE JOHNSON

Roger W. Burdette, Editor