rodan 炉壇

A fire box. The fixed, box-like hearth providing a place for a bed of ashes on which charcoal is burned to heat a kettle of water to make the tea served at a tea ceremony. There are two types: sumihitsu 炭櫃 and dodan 土壇. The sumihitsu is about 1.5 cm deeper than the dodan but otherwise they are similar. They reach a depth of about 45 cm below the surface of the straw mat *tatami 畳 and are usually made of cypress, lined with coarse clay approximately 7 cm thick. The soil for the clay is brought from Inari 稲荷 in Kyoto and is mixed with finely chopped ivy leaves. Special paper, called tengujō 天狗帖, is pasted on the four top corners which are then covered with a thin layer of fine clay. The inside area measures 29 square cm by about 45 cm deep. A frame *robuchi 炉縁, is set on top of the clay-lined box level with the surface of the tatami. The clay-lined cypress fire-box is considered the most formal, and those made of stone, iron, copper and even ceramic are used for informal occasions. Fire-resistant stones used for the stone rodan were obtained from Kurama 鞍馬, Izu 伊豆 and Nikkō 日光.
In about November, the portable brazier *furo 風炉, is replaced by the fixed hearth, and the fire-box is re-plastered . When the clay lining is dry, the box is filled with the desired amount of ash.