Treated posts

Treated timber posts are those that have been treated with chemical impregnating agents. This is done to protect the wood from damage by micro-organisms (bacteria and fungi) and insects. During the preservation process, the impregnating agent penetrates the wood and forms a mould-resistant layer. This layer ensures that the wood is less susceptible to damage and therefore lasts much longer. Impregnation causes the wood to change colour. Impregnated posts are usually green in colour. In recent years, impregnating agents have also been developed to give the wood a natural brown colour.

The impregnation process

The softwood posts are usually pressure-impregnated in a hermetically sealed boiler (autoclave). A vacuum pump is used to pump the air out of the boiler until all the air is removed from the wooden posts. The impregnating agent is then added and pressed into the wood. The impregnation process takes around 4 hours and is fully computer-controlled, with quality being checked at all times. If treatments take place after impregnation, this can lead to wood deterioration at the place of treatment. It is therefore important that the wood is treated before the treatment process begins. After wood preservation, it is best to let the wooden posts dry for some time before using them. If the posts are dried in the open air, this drying time depends on the weather conditions. When there is plenty of wind, sun and no precipitation, drying is fastest. To speed up drying, impregnated posts can also be dried in a fixation boiler.