Raku firing is a process featuring rapid heating to maturity of glazes that melt at about 1700f. Most often, raku kilns are simple propane driven structures. Raking bisqued, glazed ware requires raising the heat in the kiln several times over roughly a half hour. When ready, the surface of a piece often looks shiny, depending on glaze characteristics.
Reaching maturity, the heat is turned off and the piece(s) are lifted out of the kiln with tongs and transferred to a nearby reducing chamber that has newspaper or some combustible material inside. The radiant heat of the ware ignites the paper and the lid of the chamber is closed. The reducing chamber slows cooling, which affects color maturation and coats the piece with a smoky patina. The piece is pulled free after cooling and perhaps cleaned of some carbonized residue.
Renowned for its often unpredictable qualities of color, raku firing produces unique results that chronicle the work’s fiery transformation of passage. With experience and familiarity, the rakuist can exert increasing influence over the tonal direction of their work. Especially, the ratio of speed from freeing it out of the kiln to sealing it in the reducing chamber is key.