Definición

• Hydrogen Embrittlement. Hydrogen absorbed into the die steel during acid etch and leads to early cracking of proof dies. This condition causes minute cracks on the surface of dies results in irregular raised lines on struck coins..
   

  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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