The frame placed around the fire-box *rodan 炉壇, in a tea ceremony room *chashitsu 茶室. The robuchi is 42 cm square, 6.7 cm high, and 3.6 cm wide on top, and slightly less at the bottom because the inner side is chamfered. The robuchi in a rural tea ceremony room *inakama 田舎間, is slightly smaller, about 39.3 cm square. Each piece of the frame butts against the side of the next in a clockwise direction. The right angle joints are locked together by tenon and mortise *hozoana ほぞ穴.
In small tea ceremony houses of 4 1/2 mats *yojōhan 四畳半, or less, a plain wooden frame is common. In larger tea ceremony rooms, and in *shoin 書院 type tea room, frames are lacquered and gold dust may be added. See *maki-e 蒔絵. Frames may be made also of black persimmon kurokaki 黒柿, or mulberry kuwa 桑. Occasionally varnish is rubbed into the wood with cloth or cotton.
During the season when the portable brazier is used (from April 1 to October), the mat used with the fixed-hearth is changed and the frame is taken off. When the fixed-hearth is set into the middle board *naka-ta 中板, or merely covered with a wooden lid *robuta 炉蓋, the frame is also removed, allowing the cover to be level with the surface of either *tatami or naka-ita.
