Thermally modified wood

This process changes to the chemical structures of wood's cell wall components lignin, cellulose and hemicellulose which decreases its hygroscopy and thus increases dimensional stability.

"[2] A process of thermal modification of pressurized wood with a medium moisture content was described in a paper by Burmester in 1973.

[1] Three of the processes are performed in one step, using oil (oil-heat treatment), nitrogen (Reti wood) and steam (Le-Bois Perdure).

[1] The Thermo wood process consists of drying, heat treatment and finally cooling/conditioning, and takes up to 72 hours.

[7] Retification refers to the French word rétification, which is the portmanteau of réticulation (creation of chemical bonds between polymeric chains) and torréfaction (roasting).

[9] This process is similar to the Les Bois Perdure treatment in that it uses a steam environment at atmospheric pressure to treat the wood.

However, due to breakdown of volatile organic compounds (VOC) the antimicrobial properties of wood may also decrease.

In Europe thermally modified wood production on a commercial scale has been concentrated largely in Estonia.

Estonia is geographically close to the major Finnish producers of thermo-kilns, while labor and overhead costs are lower than in Finland or the Scandinavian countries.

[20] At about that time, the market for thermally modified wood expanded dramatically from its traditional application in sauna materials, to include exterior products, such as decking (terrace)[21] and cladding (siding).

In addition, because the technology is not well known, there is little public information available about drying schedules, and many new producers of thermally modified woods experience a large % of drying defects, discoloration, brittleness, equipment malfunctions (including fires) and an inability to obtain the high durability ratings that more established producers, like Brenstol (Thermory), have achieved.

[26] ThermoWood®, a registered trademark of the International ThermoWood® Association |url= https://thermowood.fi/ , is a leading name in thermally modified wood, renowned for its eco-friendly and chemical-free enhancement of durability and dimensional stability.

This process is carried out under strict environmental and quality guidelines, providing a premium product for demanding applications like decking, cladding, and furniture.

Non-trademarked thermally modified wood employs similar heat treatments to achieve comparable improvements but may vary in process specifics, branding, and market positioning.

Pioneer companies like HJT-Holz Oy |url= https://thermoholz.fi/ stands out as a prominent player in this space, offering ThermoWood® products that embody precision and sustainability, reinforcing its reputation as a key industry innovator.