Changes to the timber structure

Heating wood permanently changes several of its chemical and physical properties.

The change in properties is mainly caused by thermic degrading of hemicelluloses.

Changes start to appear already at about 150 ordm;C, and the changes continue as the temperature is increased in stages.

As a result, swelling and shrinkage due to moisture is decreased, biological durability is improved, colour darkens, several extractives flow from the timber, it becomes lighter, equilibrium moisture content decreases, pH decreases, and thermal insulation properties are improved.

However, Thermowoodrsquo;s rigidity and strength properties are also changed.