paper clay vs porcelainware

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. 

porcelainware

noun
  • Items made from porcelain. 

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