As a by-product of making bamboo charcoal, Yamamoto-san makes hana-sumi from carbonised branches, flowers and leaves of various plants. After laying the bamboo into a thick iron kettle, various plants are placed in the space between the bamboo and the lid, and the kiln is then fired for several hours to carbonise what is inside. While the charred plants retain their shape without rotting, they are very fragile and extremely sensitive to impact. The rough texture of the original material is given a matt finish, while the smooth material is given a lacquered sheen.