Yakisugi & Shou Sugi Ban: Preserving Wood Like the Japanese
Before chemical preservatives became a mainstay in carpentry, building with wood was always fraught with problems. Although wood was one of the cheapest building materials available and easy to work with, it was still organic. It could absorb moisture from the air and rain, growing moldy and rotten over time. Even worse, unprotected wood attracted termites that would destroy the wood and weaken the structure. And the worst of all, it was flammable. History is littered with accounts of great cities burning like giant tinderboxes, all because wood was used to build every structure.
But over three centuries ago, the Japanese discovered they could protect wood from the elements using, interestingly enough, fire. By carefully charring the surface of the wood, you could remove the moisture from the dead plant cells while preserving the cell structure. The process also hardened the surface without making it brittle. Mold and bacteria couldn’t survive on a surface like this, and termites couldn’t get past the tough exterior.
Yakisugi became a staple of Japanese construction, but it wasn’t until the last century that it really gained popularity elsewhere in the world. And it only took two centuries to happen.
Yakisugi & Shou Sugi Ban in Japan
The Japanese typically used Yakisugi in rural architecture in the 18th century, a wooden cladding for houses in villages. It began the tradition of black houses and buildings, which might at first seem an odd choice for a place with warm weather. But the color was a natural consequence of charring the wood, and it’s more practical to have strong, weather-resistant wood than a lighter color wood that’s unprotected. Today, houses built with Yakisugi use a modern flourish on the old way of building, a rustic style that compromises on none of the luxuries we enjoy today.
Yakisugi & Shou Sugi Ban Around the World
Terunobu Fujimori, a Japanese architect, and Maarten Baas, a Dutch furniture designer both use works that that prominently feature Yakisugi. The deep colors of the soot contrasts with the less intense color palette of everyday life. The wood grain has a rich texture unlike any other material, lending a visual distinctiveness to the pieces.
Even though they use it as a basic building material in Japan, people still see it as a high-design building material in other parts of the world. To them, Yakisugi is more an aesthetic than a culture.
How It’s Made
Yakisugi or Shou Sugi Ban isn’t as simple as sticking a plank of wood over a fire. It requires a great level skill and knowledge of the wood you’re using to master the art of wood preservation. Burn the wood too much and you risk making it brittle and weak. Char it too little and you don’t get the right coloration or hardening. Yakisugi is a painstaking process, and isn’t for the faint of heart.
1. The wood is selected
The Japanese have always used two kinds of wood: cypress or cedar. While most people agree that these are the perhaps the best suited for Yakisugi, in recent years, artisans have been experimenting with other kinds of wood that have similar properties to these two.
At Underlyn, we use the finest, hand-selected pine wood for our gorgeous line of Fire-Crafted frames.
2. The wood is carefully treated over a flame
To achieve the right level of charring, the wood is hung over a flame and exposed to the extreme heat to gradually carbonize the surface. But this technique requires years of practice, since you need to be able to discern the level of charring without checking the wood.
These days, it’s a much more common practice to use propane blowtorches to do the burning. These aren’t your typical food-grade torches either — you need a high intensity flame, the sort you get in an ice-melting torch.
The flame evenly moves across the wood until the surface goes black and develops a layer of soot.
3. The charred wood is cooled down
Before you start working on it, the wood needs to be cooled down first to prevent warping. Artisans typically sprinkle a few drops of water across the wood and let it dry completely, making sure the wood is no longer warm. Then it’s ready for the next step.
4. The wood is wire-brushed
An artisan uses a wire brush to clear out the layer of soot left by the flame. The brush travels along the direction of the grain, smoothly driving out the fine charcoal dust. Depending on how he wants the finish, he can choose a different brush.
For a darker, bubbled texture like crocodile skin, a soft-bristled brush is used. For a smoother finish, a tougher bristled brush is required. A lighter brushing leaves more of the char in, giving it a darker color, while a continued brushing can result in a ‘tiger-stripe’ finish that shows off the wood grain.
The wood becomes more porous in this condition, so the next step comes immediately after.
5. The wood is sealed with natural oils
While some modern methods use polyurethane for durability, the traditional Yakisugi or Shou Sugi Ban is finished with a coating of natural oils, usually linseed. The oil is worked into the wood slowly, letting the freshly charred surface drink in the liquid and retain it, effectively sealing the wood like a patina. The wood is let out to dry and oil is reapplied where necessary. Often, the artisan may give the wood another blast with the blowtorch to finish off the process.
People have been heat-treating wood around the world for centuries. But for the Japanese, it’s more than that. Yakisugi was different because it married the traditional Japanese culture with a tasteful sense of aesthetic. When the country opened up to the world in the 19th century, their way of life was irreversibly changed.
But that was also true of the rest of us. The world today has taken much of what the Japanese have had to give and made it our own. And in doing that we’ve learnt much from them. Yakisugi is no different. We saw the art in a place they already knew it existed, and we couldn’t help but take a page from their knowledge centuries old.