noun (n)

• the formation of a crust(noun.process)

  Synonym:
  encrustation
  

  source: wordnet30
• a hard outer layer that covers something(noun.object)

  Synonym:
  crust, encrustation
  

  source: wordnet30
• a decorative coating of contrasting material that is applied to a surface as an inlay or overlay(noun.artifact)

  source: wordnet30
• The act of incrusting, or the state of being incrusted.(noun)

  source: webster1913