Raku Ware - Oxidation Reduction

Oxidation Reduction

In raku firing, the aluminium container acts as a reduction tube, which is a container that allows the carbon dioxide to pass through a small hole. A reduction atmosphere is created by closing the container . A reduction atmosphere induces a reaction between oxygen and clay, which affects the color . It also has extraordinary effects on the metals inside the glaze. Reduction is a decrease in oxidation number . Closing the can starves the air of oxygen after the combustible materials such as sawdust catch fire and forces the reaction to pull oxygen from the glazes and the clay . For example, luster duster gets its interesting color from deprivation of oxygen. The reduction agent is a substance from which electrons are being taken by another substance . The reaction uses oxygen from the atmosphere within the reduction tube, and, to continue, it receives the rest of the oxygen from the glazes . This leaves ions and iridescent luster behind. This creates a pleasing metallic effect. Pieces with no glaze have nowhere to get the oxygen from, so they take it from clay. This atmosphere will turn clay black, making a matte color, without sheen.