engobe vs kaolin

engobe

noun
  • A non-black clay slip coating applied to a ceramic body to give it decorative color or improved texture. 

  • A clay slip which is colored with metal oxides or stains, used for coating the surface of a pot either before or after bisque firing. 

kaolin

noun
  • A fine clay, rich in kaolinite, used in ceramics, paper-making, etc. 

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