Definição

• Activated Surface.  A chemical change to the metal surface of a numismatic item which renders it susceptible to oxidation, toning or tarnish by natural processes. Cleaning agents are most notorious for leaving such a state on numismatic items (and is one reason why inexperienced persons should never clean numismatic objects). Such chemicals are called surfactantz, surface active agents. Some metal cleaning procedures, notably bright dip, leave the surface in an activated condition.

  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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