Reduction or Reducing atmosphere
Reduction refers to an atmosphere during firing in which the supply of oxygen is limited, creating an environment with reduced oxygen availability. This type of atmosphere alters the chemical reactions of the metal oxides present in the glazes and clay, resulting in a deeper color palette and often metallic or iridescent finishes. In a reducing atmosphere, oxygen is consumed by the incomplete combustion of fuels, causing the metal oxides to change their oxidation state. For example, in a reducing atmosphere, iron oxide can be reduced to a lower form of oxidation, producing colors such as dark green, black or more intense shades of blue and purple, depending on other factors such as temperature and glaze composition.
In addition to the impact on color, the reducing atmosphere can influence the density and texture of the glaze. Pieces fired in this environment often have rougher and more textured surfaces, which can be exploited for decorative effects. However, precise control of the reducing atmosphere is crucial, as excessive reduction can lead to defects such as cracking or crawling.Interesting Fact
Celadon, a characteristic glaze of Chinese ceramics, is fired in a reducing atmosphere to achieve its distinctive translucent green color. This glaze has been highly valued since the Song dynasty (960-1279 AD) for its elegance and sophistication, becoming a symbol of Chinese ceramic mastery and being imitated by other ceramic cultures around the world.Helpful Tip
When working in a reducing atmosphere, it is essential to continuously monitor oxygen flow and combustion in the kiln to maintain a controlled environment. Use calibrated thermocouples and pyrometers to adjust the temperature and fuel supply, avoiding fluctuations that can affect the quality of the glaze.
