Thermally modified timber goes through a 3-stage kiln process which uses high temperature. It takes 24-72 hours to complete a full cycle. During the high temperature phase, the wood is protected from combustion by using steam. In that time, the moisture of the wood is almost completely removed and added back to a precise amount. The natural acids and sugars are modified from the extreme heat which changes the physical structure of the wood. The wood’s ability to absorb moisture is declined making it less prone to rot and decay. The equilibrium moisture content (EMC) of the wood decreases. This means the swelling and shrinking of the wood material due to moisture variations can be reduced by up to 60% as compared to unmodified wood. The most apparent change is that the wood darkens throughout, giving domestic wood the look of desirable imported wood.
The 3-phase process uses only heat and water to change a wood species ability to withstand the elements, making it one of the most natural, chemical free ways to extend the life of wood products.
The temperature in the kiln is raised rapidly to around 100˚C (212˚F), affecting the natural composition of the wood. Steam is introduced to prevent the wood from checking in the high heat. The moisture content of the wood is reduced from 15-20% down to nearly zero.
One peak temperature is resulting in a light cook, 190˚C (374˚F), and the other is the dark cook at 210˚C (415˚F). The higher and longer the heat, the darker the wood becomes throughout. At these high temperatures, the lack of oxygen within the chamber is what prevents the wood from burning.
Cooling & Re-Conditioning
Temperature is reduced by introducing steam. The steam cools and conditions the wood to a moisture content of 4-6% improving dimensional stability.
The color of wood will darken in tone through the thermal modification process. It is important to understand that it is a natural product and the grain, original color variances and characteristics of the wood still are present. The wood is darkened throughout so any sanding or refinishing will bring the wood back to the original color without staining. In an exterior environment TMT products do move to gray when unfinished. Finishes with UV inhibitiors help slow this process similar to non-modified products. The color change of the thermally modified wood is especially useful in the flooring industry since it can be used to emulate tropical wood species
AWCo products are an excellent natural option for interior and exterior wood applications. Thermally Modified Timber (TMT) is suited for siding, flooring, decking, window and door manufacturing and much more. TMT material has limited expansion/contraction and can have stains and paints applied like standard wood products.
Thermally modified wood can be used in an array of commercial and residential applications. Popular applications are in external environments where moisture and humidity would compromise a lesser-grade material.
Improved aesthetics and durability are met with AWCo Thermally Modified Timber. Our material can be used in place of more expensive tropical wood species and is a domestic, environmentally conscious option.
AWCo is a premier choice for sustainably harvested thermally modified timber.
After the wood has been thermally modified its properties are more stable than standard kiln dried wood. The swelling and shrinking of wood due to moisture variations can be reduced by up to 60%.