Firing in Pottery: How Clay Becomes Ceramic

Firing is the process of heating clay and glaze in a kiln so they undergo permanent physical and chemical change. It is what turns soft, fragile clay into durable ceramic.

For beginners, firing is where many pottery terms finally connect: bisque, glaze, kiln, cones, and shrinkage all make more sense once you understand what firing does.

What firing does

  • Removes remaining water from the clay.
  • Creates irreversible ceramic change.
  • Hardens and stabilizes the clay body.
  • Melts glaze ingredients so they bond to the surface.

Common firing stages

  • Bisque firing hardens the clay after it has dried.
  • Glaze firing matures the glaze and finishes the piece.
  • Some work uses special approaches such as Raku or other atmosphere-dependent firings.

Results depend on heat, speed, cooling, oxygen, and how well the clay and glaze fit each other.