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Preservation of wood and wood products with chemicals

Many wood species have heartwood with insufficient or no natural resistance to wood-destroying organisms. Heartwood with insufficient or no natural resistance will decay (attacked by wood-destroying fungi) when it becomes and remains wet. It will be attacked by wood-destroying beetles and termites in many end uses. Wood in the sea is susceptible to damage by marine animals and fungi. The sapwood of all species is susceptible to attack by all wood-destroying organisms and by staining fungi. Where the natural protective constituents are insufficient or totally absent, wood and wood products are treated with preservatives to protect them from the damaging effects of fungi, bacteria, insects, water, weather or fire; providing long-term conservation of structural integrity and improving the resistance.

Wood or wood products treated with wood preservatives can be found, for example, in the building and construction sector (wood lattices, bridges, alpine cabins or chalets, etc.), in gardening and landscaping (fences, arches, etc.), as well as in agriculture (poles for fruit and wine growing), toys and playground equipment, avalanche and noise barriers, railway sleepers and telegraph poles. Depending on where the wood is used, use classes in a range of 0 to 5 are defined. For use classes 1 to 4, there is an increasing risk of wood becoming and remaining wet and a concomitant increase in risk of fungal decay.

Wood preservation can take place in specialised companies, as a part of the production in sawmills (where sawmills offer not only sawn timber, but also treated timber) or in other woodprocessing industries, e.g. window and door production.

In Europe, it is claimed that there are approximately 250 installations with a production capacity of more than 75 m3 per day. (JRC Europe