Shou Sugi Ban 焼杉板 (or Yakisugi) is the Japanese method of preserving wood through carbonization, a chemical reaction otherwise known as “fire” that seals the pores of the wood with carbon. This carbon is then often sealed into the wood using an oil-based sealant.
Traditionally Shou Sugi Ban is used to prepare boards for use as exterior siding on buildings though in the last few years the finishing process has gained popularity as a treatment for interior wood used in furniture and wall facades.
The traditional method often has the craftsman binding two or three long Japanese cedar (Sugi) planks together with a fire lit between the boards. The boards are then stood upright to form a chimney along which the fire progresses until the boards have been evenly charred. More modern methods may replace process this with scorching via a common handheld gas torch. At this point the boards are quenched with water and scrubbed with a stiff bristled brush or broom to removed loose soot and carbon material and left to dry. Finally the planks are sealed with an oil leaving a gorgeous shimmering coal-like appearance.
The benefits of the finish go beyond aesthetics as Shou Sugi Ban offers increased fire resistance, reduces susceptibility to rot, and protects the wood from damaging attacks by insects.