Building and Carpentry

What is 'tanalised' wood?

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March 17, 2008 4:19PM

'TANALISED' timber has been impregnated with a preservative solution under high vacuum pressure in an industrial vessel. This treatment process ensures deep penetration into the timber cells, for a longer-lasting protective result against fungal decay and insect attack than the application of a surface coating. Pressure-treated timber is leach resistant, ensuring a long and trouble-free service life in a wide range of conditions, and assured performance in sensitive environments such as vegetable plots and areas of wildlife. Desired service lives range from 60 years for internal timbers and 30 years for external timbers such as fence posts in ground contact. The treated timber initially assumes a green colouration, which fades to a honey brown over time and eventually a silver grey. No surface applied product is needed to maintain the integrity of the treatment. Timber treatments are specified in line with BS8417, in order to ensure that an appropriate level is given according to the end use of the timber. The Use Class system is an indicator as to how the timber should be treated in order to match its end use. In the UK, 'TANALITH E' is the latest generative preservative, utilising a copper azole formulation which incorporates biocides that are also used to protect food crops. 'TANALISED', and 'TANALITH' (the preservative) are both internationally registered trade marks of the preservative manufacturer, Arch Timber Protection. These brands have been established since the 1940s, and are a key signature of treatment quality. An alternative to high-pressure treatments is VACSOL, which is a product applied under low pressure to create an envelope seal of protection. VACSOL Aqua is a water-based formulation, commonly used in the UK and across parts of Europe, and can impart a 60 year desired service life against fungal decay and insect attack for constructional timbers. Visit for further details of the Arch Timber Protection product range.