Kiln Atmosphere
Oxidation/Reduction

Oxidation

  • clean flame or radiant heat from an electric kiln
  • no excess unburned carbon, and therefore efficient use of fuel
  • glazes are generally brighter, especially in the earthenware range

Reduction

  • oxygen is reduced: dirty smoke and soot results
  • unburned carbon changes the color mainly of copper and iron for beautiful effects in certain glazes.

A REDUCTION ATMOSPHERE OCCURS WHEN excess heated carbon (monoxide) steals oxygen atoms from any iron or copper present. This changes the molecular structure of both. Carbon monoxide becomes carbon dioxide, and the number of atoms present in the copper and iron effects the network of interlinked atoms that reflects light, thus changing their color.