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TOP   〉 Environmental Activities:Our Approach to Sorghum

Our Approach to Sorghum

Effectively using sorghum stalks, an agricultural waste, as a substitute for wood

What is sorghum?

Known as kaoliang in China and morokoshi in Japan, sorghum (or millet) is an annual grass of the Poaceae family that is cultivated widely as a cereal crop in the United States, India, China, and other wide regions of the world.

Sorghum grain is currently used as a cereal for human food and animal feed, and the stalk remains mostly unused after the harvest.

Koyo Sangyo developed sorghum board for use as a wood substitute by attaching those stalks together with our original adhesive KR Bond® then molding it into a board.

With a hint from a collection of interviews with writer Ryotaro Shiba…

In the summer of 1980, Koyo Sangyo’s founder Tsugane Tanaka came across the comment that the “sorghum stalk is as hard as bamboo” in a collection of interviews with renowned Japanese author Ryotaro Shiba. With that hint, the development of sorghum board began.

Sorghum board, which makes effective use of sorghum stalks that are not needed after the grain has been harvested, finally became a product after approximately 17 years development. Today, the company is continuing its work on developing new uses for the sorghum board and its practical application.

In particular, because sorghum’s epidermis is covered in a wax layer, bonding it with normal adhesive is difficult. The adhesive technology of Koyo Sangyo’s original adhesive KR Bond® (water-based polymer-isocyanate adhesive: JIS K6806) made it possible to solve this problem, and in 1996 we established a local corporation (Shenyang Xinyang Sorghum Plywood Co., Ltd.) in Shenyang City, Liaoning, China, and began production.


Uses of sorghum board


As the core material in thin tatami mats
Although sorghum board is of plant origin, we utilize its characteristic dimensional stability for use as the core material for residential barrier-free thin tatami mats, sold under the product name Healthy Shizuka®. In addition, the product Attakka-kun, which accommodates floor heating, is also available.


Koryo Board® is available as interior decorating materials for stores, hotels, offices, etc. It utilizes the natural design of the cross-section of the sorghum board.

It is widely available in the United States under the product name Kirei Board®.

Visit for information about Kirei Board® in the United States.