Definition

• Tumbling.  Cleaning or polishing metal items in a rotating barrel. The action takes place by the objects constantly knocking against each other or other objects, deburring compound, added to the total mass, as shot or ball bearings. Obviously struck pieces cannot be cleaned or polished this way but blanks can be tumbled before striking. The blanks are separated from the deburring compound by screening or sieving.  See deburr.

  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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