{"id":34775,"date":"2023-02-23T08:30:44","date_gmt":"2023-02-23T06:30:44","guid":{"rendered":"https:\/\/revistadinlemn.ro\/?p=34775"},"modified":"2023-06-13T11:12:56","modified_gmt":"2023-06-13T08:12:56","slug":"what-is-shou-sugi-ban-how-it-is-made-and-why-burnt-wood-is-resistant-to-fungi-insects-moisture-and-fire","status":"publish","type":"post","link":"https:\/\/revistadinlemn.ro\/en\/2023\/02\/23\/ce-este-shou-sugi-ban-cum-se-face-si-de-ce-lemnul-ars-este-rezistent-la-ciuperci-insecte-umiditate-si-foc\/","title":{"rendered":"What is Shou Sugi Ban, how it is made and why burnt wood is resistant to fungi, insects, moisture and fire"},"content":{"rendered":"

An ancient method of protecting and highlighting wood design is burning. It has been practiced in various parts of the world, but it was Japanese carpenters who perfected it. Shou Sugi Ban - burned cedar plank - is a technique in which wood is burned, brushed and cooled with water so that its surface is covered with a layer of charcoal. The water-cooling is done in a controlled way so that the charcoal layer cracks in a certain pattern that gives the plank a particular aesthetic. But the main benefit of this type of burning is the very good resistance to attack by fungi, insects and fire. Exterior cladding<\/a>, fences<\/a>, shingle<\/a>\u00a0wood using this technique lasts 80-100 years without maintenance. Find out why burned wood is so strong below.<\/p>\n

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What happens when the wood surface is burned<\/span><\/h4>\n

To understand why burning protects wood we need to start with its main chemical compounds: cellulose, hemicelluloses and lignin.<\/p>\n

Cellulose<\/em> is the most important structural substance because it forms the wood cell wall, which determines its main physico-chemical properties. It accounts for 40-45% of the mass of anhydrous (completely dry) wood. Cellulose decomposes at over 150\u00b0C, a property on which alcohol is obtained by dry wood distillation<\/a>. It is a food source for insects and micro-organisms and is very water-loving.<\/p>\n

Hemicelluloses<\/em> are very similar to the cellulose they accompany in forming the cell structure. Some are bound to cellulose, together forming the skeleton of the plant, others are bound to lignin. They account for 20-40% of the mass of anhydrous wood, are more unstable than cellulose and decompose faster, are a food source for micro-organisms and have a high affinity for water.<\/p>\n

Lignin<\/em> is a complex, amorphous chemical substance. It surrounds the cellulose skeleton giving the wood stiffness and mechanical strength. The percentage of lignin in the mass of dry wood is 15-35%. Lignin is water resistant, transferring this property to the cell walls.<\/p>\n

When the wood surface is burned, the cellulose and hemicelluloses decompose and the food source for insects and fungi disappears. The percentage of lignin on the surface increases which leads to increased water resistance. Burning takes place in stages, with the temperature gradually increasing as the rapidly decomposing elements disappear. The first to burn is cellulose. As it burns, lignin gradually turns to charcoal. This needs a much higher temperature to burn completely, and so the rest of the wood is protected until the burning temperature of charcoal is reached.<\/p>\n

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Stages of the Shou Sugi Ban technique<\/span><\/h4>\n

The technique of Shou Sugi Ban or Yakisugi, as it is also known, was used a long time ago, but flourished in the 17th century. At that time it was applied not only to protect houses or fences, but also to create true works of art. With the advent of modern wood preservatives, the method was abandoned for a time. However, it made a comeback in the 2000s, mainly thanks to designers and architects who combined the old method with modern materials to achieve outstanding effects.<\/p>\n

The classic method has the following steps:<\/p>\n