How Stable is Accoya?

To demonstrate the stability of Accoya, we have conducted multiple rounds of a stability test. Taking Accoya, a thermally modified product, and white oak, applying a finish on one side (which you should NEVER do), and placing them on a flat surface to bake in the sun (also NEVER do). Each sample tested was short in length; in doing so, we created this environment because it is the perfect recipe for cupping boards. After a period of time, we brought the pieces inside to demonstrate the amount of rock each board has.

Accoya’s Chemical modification

Accoya takes a different approach to stability through modification. Whereas many manufacturers achieve stability through thermal modification, Accoya’s approach is through chemical modification. Accoya undergoes a process called acetylation. To summarize, wood has two chemical groups: hydroxyl and acetyl groups. Hydroxyl groups bond to water much more easily than acetyl groups do.

During acetylation, Accoya uses acetic anhydride to convert many of these hydroxyl groups into acetyl groups, significantly reducing the wood’s ability to absorb moisture. Because the cell walls take up far less moisture as humidity changes, they experience dramatically less swelling and shrinking. The result is a wood product with exceptional stability and significantly reduced movement compared to untreated wood.