Glaze firings can occur in gas or electric kilns. Depending on the clay body, the piece may first be bisque-fired to remove the water from the clay and to make the pots more durable for glazing. Glazes are then applied by dipping, brushing, or spraying. Layering the glazes can create unique effects.
Electric kilns provide an oxidation firing where a steady flow of oxygen circulates during the process. Gas kilns allow for the manipulation of the flow of oxygen. When deprived of oxygen (reduction firing) the chemicals in the glazes produce different colors. (e.g. - The copper in a glaze will turn red in reduction and a beautiful turquoise in oxidation.)