Définition

• Pattern.  (1) A model from which something is made, usually in hard form. A pattern is required for modern die cutting operations, particularly for the die-engraving pantograph.
  The purpose of the pattern is to convey the configuration of the surface, the design and lettering – it's modulated relief – to be cut into a die or formed into a mold. Die patterns used in a pantograph must be in a hard surface to sustain the tracking by the tracing stylus.
  The artist's original model does not have to be in hard form, as this can be in wax,
  plaster or clay. If a cast medal is to be made, a model in any of these compositions is satisfactory.  However, if the artist's original pattern is to be made into a die, this must be rendered into hard form. Formerly this was done by electrogalvanic casting (the result is called a galvano pattern), more recently by epoxy casting (called an epoxy pattern).
  The galvano or epoxy pattern from this second stage is mounted on the die-engraving pantograph. At this stage it is still a pattern, but a better term is dieshell  from which the die is reduced and cut (a dieshell is called a former in Great Britain).
  If a pattern is used for several items (as the same design in several sizes, or different items) it is called a master pattern.

  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

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