It is raku’s unpredictable results and intense color that attract modern potters. These patterns and color result from the harsh cooling process and the amount of oxygen that is allowed to reach the pottery. Depending on what effect the artist wants, the pottery is either instantly cooled in water, cooled slowly in the open air, or placed in a barrel filled with combustible material, such as newspaper, covered, and allowed to smoke. Water immediately cools the pottery, stopping the chemical reactions of the glaze and fixing the colors. The combustible material results in smoke, which stains the unglazed portions of the pottery black. The amount of oxygen that is allowed during the firing and cooling process affects the resulting color of the glaze and the amount of crackle.
WIKIPEDIA CONTRIBUTORS,”RAKU WARE,” WIKIPEDIA, THE FREE ENCYCLOPEDIA, HTTPS://EN.WIKIPEDIA.ORG/W/INDEX.PHP?TITLE=RAKU_WARE&OLDID=788924453 (ACCESSED JULY 12, 2017)