Thermally modified wood: from preservative to potential substitute Hoang, David
For decades, wood has been a victim of the wrath caused by insects and fungi degrading wood, using its natural properties for food and habitat. There are preventative measures humans can take to prolong the life of wood products. Pressure treating wood with chemicals such as CCA and ACQ provide adequate protection against organisms that feast on wood. The process involves using harmful chemicals that may leach out of the treated wood into the surrounding environment, causing potential hazards to the health of beings. Thermally treating wood preserves the specimen without the use of chemicals. Anti-organism performance is comparable to that of the chemically treating wood. Using high temperature and steam in specialized kilns, cell structures are modified and the food sources for fungi and insects are eradicated. Though the changes physically to the wood prevent it from being degraded by organisms, the changes affect the mechanical properties as well. The natural colour of the wood darkens with the increase in temperature, and swelling is reduced when exposed to humid environments thus increasing dimensional stability. Thermal modified wood also increases in brittleness and decreases in overall bending strength. Thermally modified wood can continue to be a method of preserving wood. However, with its modified properties after heat treatment, the change to consistent hues throughout the cross-section resembling exotic wood species can enter new markets such as being a substitute for non-structural exotic wood products.
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