etching vs mezzotint

etching

noun
  • The art of producing an image from a metal plate into which an image or text has been etched with acid. 

  • The image created by this process. 

mezzotint

noun
  • A form of intaglio etching in which a metal plate is roughened evenly and then smoothed to bring out an image. 

  • An etching or print made using this method. 

verb
  • To make such etchings 

How often have the words etching and mezzotint occurred in a corpus of books? (source: Google Ngram Viewer )