Chiku-shin Ji-ari Shakuhachi are made using Ji a plaster material mixture made out of polishing powder and urushi. Once this mixture is made, then it is applied to the inner walls of the bamboo. To achieve a smooth like taper towards the end of the bamboo. The tapering must be precise measurements and percentage of taper to the length of the bamboo. It is a process of adding, smoothing, adding, smoothing, measuring, and adding.... Sanding, smoothing and measuring again this takes a great deal of time and patience.