Also written 墨芯. A bamboo brush or drawing spatula. The tip of a piece of bamboo is sharpened into a pallet shape and then split very finely (approximately 30 divisions) to form a brush. The long-grained Japanese bamboo madake 真竹 (Phyllostachys bambusoides) is used and the tip measures 10 to 15 mm wide. The bristles are soaked in the silk wadding of a carpenter's ink pad *sumitsubo 墨壷, and the sumisashi is used in the same way as a cartographer's pen -- to draw a line or special marks as a guide to cutting or notching on wood for construction. Often used in conjunction with the carpenter's ruler *kanejaku 曲尺. The head of the sumisashi is carved into a round shape and softened slightly by tapping with a hammer. This end is used as a brush for writing letters and symbols.