Created from rapeseed oil soot, Koukaboku is the pride of Kobaien. This ink stick was developed by Izumino Jougen'i, the seventh-generation president of the company. Koukaboku is a superb ink stick has been much loved by many people over the 270 years since it came into being.
Kinshoukaku is a top-grade ink stick made from the soot of rapeseed oil. It is well suited to ganpi-shi paper, torinoko-shi paper, and to paintings. This ink stick is created according to a secret recipe that was developed through repeated experimentation over the course of more than 60 years. The dark parts of the Kinshoukaku ink stick are close to a pure black in color, while the lighter parts of the stick produce a brownish black. This ink stick is suited to calligraphic works in Chinese characters and Japanese kana characters, to the hand-copying of sutras, and so forth.
Hiraraden Haienkyo is modeled on a particularly famous mirror included in the historical relics stored in the Shoso-in national treasure house in Nara, Japan. It is an expression of the beauty of mother-of-pearl work using ink. This ink is mainly used for artistic appreciation.
The soot that gathers on the lids is collected.
To ensure that the soot gathers on the lids evenly, all the container lids are moved every 20 minutes.
While the weight of a piece of ink stick is 15 grams, approximately 25 grams of ink must be poured into the wooden mold,
due to shrinkage when the ink stick dries.
It is then carefully placed into the wooden molds.
From the second day onward, they are gradually transferred to wood ash with a lower moisture content.
This method of drying using ash is continued for one week for small ink sticks and 30–40 days for large-sized ink sticks.
Indoor drying usually continues for approximately two weeks to three months.