faience vs paper clay

faience

noun
  • A type of tin-glazed earthenware ceramic. 

  • The beads and small ornaments of the eastern Mediterranean. (Of bronze and iron age manufacture using frit technology.) 

paper clay

noun
  • Clay mixed with shredded paper or other fibres, valued for its strength and light weight in the production of large ceramic works. 

  • A kind of uniformly light-coloured clay composed of fine particles, used in the production of paper and wallpaper; kaolin. 

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