Acetylation Process

Step 2

The physical properties of any material are determined by its chemical structure. Wood contains an abundance of chemical groups called “free hydroxyls”. Free hydroxyl groups absorb and release water according to changes in the climatic conditions to which the wood is exposed.

This is the main reason why wood swells and shrinks. It is also believed that the digestion of wood by enzymes initiates at the free hydroxyl sites – which is one of the principal reasons why wood is prone to decay.

Acetylation Process

Step 3

Acetylation effectively changes the free hydroxyls within the wood into acetyl groups. This is done by reacting the wood with acetic anhydride, which comes from acetic acid (vinegar when in dilute form).

When the free hydroxyl group is transformed to an acetyl group, the ability of the wood to absorb water is greatly reduced, rendering the wood more dimensionally stable and extremely durable.

Acetylation Process

Step 4

Acetyl groups are already naturally present in all wood species. This means that the manufacturing process adds nothing into the wood that does not already occur within it.

The end product, Accoya® wood, does not add toxins to the environment. The effect of altering the wood’s chemical structure, as opposed to merely altering its chemical content, is to create an end product that is dramatically superior to its source species.

Acetylation Process

Step 5

Accoya wood is modified right through the cross section whereas, by contrast, virtually all other treatments merely insert chemicals (such as oils, ammonia or metal compounds) into the wood, improving durability, to a degree, but not dimensional stability.