定義

• Cratex Abrasive. A soft rubberized substance with abrasive embedded, much like the eraser on the end of a pencil. It is used for removal surface deposits of lead disease, tin pest and white rust and infrequently in die engraving. It is color coded according to the coarseness of the abrasive: coarse is green, medium is dark brown, fine is reddish brown and very fine is gray. Fine is used for most numismatic applications.
                                                                                                                         

  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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