A reduction atmosphere occurs when the amount of available oxygen is reduced. This may not sound like things that will affect your pottery, but it can. The oxidation process, for example, can alter the color of the glazes or paint you’ve chosen to use. The reduction process, when oxygen is leeched out of your kiln atmosphere and pottery, can change the texture of your clay. Learn what’s going on in your kiln before you fire your next project. In firing a pottery kiln, the materials will normally convert to their oxide forms. For example, when copper carbonate is fired, the carbon will detach and burn off. As soon as the copper-carbon bond is broken, available oxygen will rush in and attach to the copper, forming copper oxide. Many potters question if there is any such thing as a truly neutral atmosphere. Their main point is that there is enough oxygen in the kiln so that the glaze and clay body materials oxidize. Carbon atoms are so oxygen-hungry that they are able to break molecular bonds. The carbon literally robs the clay and glaze materials of their oxygen. When the carbon reduces the amount of oxygen in the clay and glaze molecules, the colors and textures of the clays and glazes can change. These changes can sometimes be quite dramatic. A kiln entering reduction at too low a temperature can result in clay and glaze defects, including bloating and carbon scoring.
