Ceramic Firing Types

Ceramic firings are categorized by their stage in the production process, the temperature range achieved, and the atmospheric conditions inside the kiln. 

Sequential Firing Stages

Most ceramic work involves at least two separate firings to transform raw clay into a finished product. 
  • Bisque Firing: The first firing (typically Cone 08–04) that transforms “bone-dry” greenware into a porous, durable state called bisque. This stage burns out organic materials and prepares the piece to absorb glaze without dissolving.
  • Glaze Firing: The second firing after glaze has been applied. The heat melts the glaze into a glass-like coating that fuses to the clay surface.
  • Overglaze/Luster Firing: A third, lower-temperature firing used for specialty finishes like metallic lusters or delicate china paints.
  • Single Firing (Once-Firing): A less common method where glaze is applied directly to dry greenware and both bisque and glaze stages are completed in one cycle. 

Temperature Ranges

Firing temperatures are measured using pyrometric cones, which track “heatwork” (the combined effect of time and temperature).
  • Low-Fire (Cone 06–04): Generally used for earthenware. It produces vibrant colors but results in more porous, less durable clay.
  • Mid-Fire (Cone 5–6): The most common range for modern electric kilns. It produces durable stoneware and functional kitchenware.
  • High-Fire (Cone 9–11): Traditional for porcelain and heavy-duty stoneware. These temperatures create highly vitrified (glass-like), extremely durable pieces.

Atmospheric & Specialty Firings

The presence or absence of oxygen during firing dramatically changes the final appearance of the clay and glazes. 
  • Oxidation Firing: Typically done in electric kilns where oxygen is plentiful. This results in bright, clean, and consistent colors.
  • Reduction Firing: Performed in gas or wood kilns by restricting oxygen. This forces the fire to “steal” oxygen from the clay and glaze, creating earthy tones, metallic flashes, and rich textures.
  • Wood Firing: Uses wood as fuel. Ash from the fire lands on the pieces and melts, creating unique “natural ash glazes” and flame-licked patterns.
  • Raku Firing: A dramatic Japanese-inspired technique where glowing hot pots are pulled directly from the kiln and placed into containers of combustible material (like sawdust). This rapid cooling and intense reduction create crackle patterns and metallic finishes.
  • Salt or Soda Firing: Salt or sodium is introduced into the kiln at peak temperature. The sodium vapors react with the silica in the clay to create a translucent, “orange-peel” textured glaze directly on the surface.
  • Pit Firing: An ancient method where pots are buried in a pit with organic materials and burned. This produces smoky, unglazed, and unpredictable finishes.