定義

• Bleed, Bleeding.  Exposure of the base metal of a plated piece, from wear or from too thin a plating (occurring from flash plating). Once the base metal is exposed its color can often identify the base composition:  copper bleeds pink, nickel-silver or white metal bleeds gray, tin or britannia metal bleeds gray-white, brass alloys bleed a typical yellow brass color, bronze bleeds brown.
  Some manufacturers, knowing that sometime during the lifetime of a piece of their making may bleed, will purposely choose a base metal similar in color to that of the plated metal; silverplating nickel-silver or white metal, or goldplating brass or oroide. This makes detecting the base composition difficult from the plated metal as the under metal will only be slightly different hue. Inspection alone may not determine the base metal. Specific gravity or other tests would have to be employed to determine base metal. Some clad metals may also bleed with an extensive wear of the clad layer. This has occurred on Sheffield plate, for example.
   See composition (2).

  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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