Unmodified wood has ‘free hydroxyl groups’ that absorb and release water as climatic conditions change, making it prone to expansion and contraction, particularly when used outdoors (windows, doors, cladding, etc), which in turn leads to splitting and rotting.

During the Accoya® Wood production process, the free hydroxyl groups within the wood are changed into acetyl groups and this reduces the ability of the wood’s cell walls to absorb water by approximately 80%, greatly improving the wood’s dimensional stability and resulting in reduced maintenance frequencies for coatings.

In addition, the change in cell structure means that fungi do not recognise Accoya® as wood and therefore do not attack it. Insects that attempt to eat the wood die of starvation because the modified structure makes it indigestible, so that it is no longer a source of food.