South African Wood Preservers Association (SAWPA)
SAWPA is an industry association which promotes the use of treated timber and treated timber products.
Understanding Timber Preservation.
A general introduction to the subject of wood technology and wood preservation. Knowledge of these fundamental factors can be of considerable assistance in gaining an appreciation of the value and importance of timber preservation and the selection of the most appropriate method of treatment. The growth of the Wood Preservation Industry has been one of the most important technical developments within the forest industry. The wide acceptance of preservation as an integral part of wood processing and utilisation has been a significant contribution to the use of what is the only structural raw material having a renewable and sustainable source of supply. There are timber structures still in existence after hundreds of years of service but there are fence posts which have rotted after only 18 months service.
This is due not only to a great variability in wood properties and our environment but also to the way in which the products are used. Wood suffers minor and gradual physical and chemical changes as a result of age. It is an organic material which can support the life of other organisms if the environment is suited to their growth and this, under certain conditions, leads to rapid breakdown of the wood. What are the circumstances in which wood is likely to be attacked by destructive agents and what measures should be taken to defeat them?
Most people can identify wood when they see it and can give names to the more familiar timbers in general use. However, much is taken for granted and relatively few may know timber in terms of a growing form of plant life or understand what structural variations produce the features characterising species which enable us to name them. The differences which exist between species are sufficient for us to realise that timber is a substance of greater diversity and character than materials such as steel and concrete. To enable the best use to be made of wood and to ensure the correct selection of the type best suited to any application, it is necessary to understand something of its structural form and characteristics and how these vary from species to species.
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Preservatives for pressure treatment of wood guidance note