Science - May 13, 2004

Oven-roasted wood is good for environment

If wood is heat-treated it can withstand more moisture and is less likely to develop wood rot. Research by Agrotechnology & Food Innovations (A&F) indicates that heat-treated wood can retain its strength. This creates possibilities for using the wood for dam walls and railway sleepers, which are often made of wood impregnated with environmentally damaging creosote.

Heat-treated wood, such as PLATO wood, Thermowood and Stellac, is already on the market, but is only suitable for light use, such as for garden furniture. Experiments done by A&F show that heat-treated wood can also be used for heavier jobs, although it needs to be treated at higher temperatures.

“The exact temperature, and how long the treatment takes are important,” explains Richard Gosselink of A&F. “According to our experiments, 275 oC is the optimal temperature, which is just below the temperature at which cellulose starts to break down, but hot enough for the wood to develop resistance to fungi.” Another advantage is that dangerous PAHs. The tests carried out by A&F produced wood that did not contain mechanical damage such as splits, which is important for wood that will be subjected to heavy pressure, such as railway sleepers or dam walls.

Further research is now needed to perfect the heat treatment, especially as there is pressure to find alternatives to chemical impregnation. Wolman salts, which contain lethal arsenic, are already forbidden, and other chemical preservatives are only allowed where there are no alternatives for large-scale uses. Creosote is permitted for railway sleepers, but in the long run is also likely to be banned.

Hugo Bouter

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