Maxwell Wood About Us The Thermal Modification Process Products and Services Contact Us NavRightSpacer


Maxwell Wood’s thermal modification technology exposes timber to high temperatures which permanently change the physical, chemical and biological properties of the wood. The benefits are: 1) reduced dimensional movement from changing humidity, 2) a significantly improved resistance to decay and weathering, and 3) an attractively darker, more consistent colour of the wood.

Not to be confused with lower temperature “heat-treatment” which only affects appearance, thermal modification produces different grades of durability, making it possible to use thermally-modified wood instead of tropical hardwoods for demanding applications like decking, exterior doors and flooring with sub-floor heating. No resins or chemicals are used in the process, which besides being easier on the environment, makes it ideal for kitchens, playground equipment and children’s toys. Thermally-modified wood is the green alternative for outdoor timber!

The thermal modification process can be divided into 3 phases:

Phase 1. High temperature drying using heat & steam. Kiln temperature is rapidly raised to approximately 100 °C, then gradually to 130 °C, during which time the moisture content of the wood decreases to nearly zero.
Phase 2. Heat treatment. Kiln temperature increased to between 185 °C and 250 °C, then held constant for 2–3 hours depending on the desired end-use.
Phase 3. Cooling and moisture conditioning. Water spray is used to lower the temperature to 80–90 °C, where re-moisturizing takes place, achieving a useable level of 4–7%.

Thermal modification is suitable for most timber species, including tropical hardwoods like Rubberwood, Merpauh and Plantation Teak. The fast growth of plantation-grown tropical hardwoods makes these species less durable than wood harvested from rain forests – the missing properties can be upgraded with thermal modification. Sapwood also presents well-known problems. With thermal modification very good durability and stability can be obtained while at the same time minimising colour differences between heartwood and sapwood.

Finally, thermally-modified wood is easy to work with. The reduction of internal tensions and friction-causing resin makes it saw more easily, with a smoother cut surface. It sands beautifully and accepts finishes as well as ordinary wood.