Cha-no-yu, 茶の湯, tea-’s-hot water, is made with ma-tcha, 抹茶, powdered-tea, that is blended with hot water using a cha-sen, 茶筅, tea-whisk. There are many different sizes and styles of chasen. The standard chasen is made of a single piece of aged ‘white’ take, 竹, bamboo, with a length of the 3 sun kujira-jaku, 鯨尺, whale-span, 11.5 cm.  Although the diameter of the bamboo varies, the standard Japanese diameter is approximately .7 sun kane-jaku, 曲尺, bend-span, or .55 sun kujira-jaku, 2.4 cm. It is a bit curious that the chasen is made using the kujira-jaku, because bamboo objects are usually measured with the kane-jaku, 曲尺, bend-span. The length...