When wood is bathed in flames, it is not destroyed but reborn, like a warrior donning resilient armor, standing fearless against the ravages of time and weather, steadfast in its purpose. This is Yakisugi.
Yakisugi is an ancient Japanese technique that involves charring the surface of wood to create a carbonized layer. During the process, organic substances are burned away, altering the wood’s internal structure, enhancing its stability and resistance to UV rays, insects, rot, and fungi. In the event of a fire, the carbonized layer also reduces heat conductivity.
Compared to untreated wood, Yakisugi not only boasts improved thermal insulation and resistance to decay and pests, but it also has a striking visual appeal. The surface texture of the charred wood, with its cracked and raised grain, creates a bold three-dimensional effect. Combined with its distinctive smoky aroma, Shou Sugi Ban engages all the senses—appearance, scent, and texture.
After being charred, the wood becomes not only more durable but also significantly extends its lifespan. The carbonized surface grants it protection from moisture and insect infestations. Thanks to its many practical benefits, Yakisugi has gained widespread use in Japan.
But how does wood become stronger when burned?
It seems counterintuitive, but the answer lies in the biological structure of wood and the unique craftsmanship of Shou Sugi Ban.
The process of charring destroys hemicellulose, while also depleting the nutrients that typically attract pests. Without hemicellulose, which contributes to the deterioration of wood, the physical properties of the material are greatly enhanced.
The Process of Making Yakisugi
Carbonization
The traditional method involves bundling the wood into a triangular structure and tying it together with damp ropes. Flammable materials, like newspaper, are placed at the bottom to ignite the fire. After burning for a while, the ropes are untied, and the fire is extinguished by submerging the wood in water, completing the carbonization of one side of the wood.
In modern techniques, the process often involves surface-level carbonization, where only the outer layer of the wood is treated with heat—akin to applying a special kind of paint. However, traditional methods involve deep carbonization, where the wood is fully charred, eliminating internal nutrients and restructuring the wood. This method is more complex and time-consuming.
Cleaning
The second step is cleaning. After carbonization, a layer of loose ash forms on the wood surface. This ash is scrubbed off with a metal brush and water, leaving the surface smoother and more visually appealing.
Oiling
The final step is oiling. A layer of tung oil is applied to the surface, followed by a gentle blowtorch treatment to ensure the oil is evenly absorbed and securely bonded. This not only enhances the protection of the charred surface but also highlights the unique grain patterns, giving the wood a striking and polished finish.
