Thermally modified wood

Thermally modified wood is any thermally-treated timber that has been modified by a controlled process of pyrolysis, in which it is heated to temperatures above 180 °C in an oxygen-free atmosphere. This process changes the chemical structure of the wood's cell wall components – lignin, cellulose and hemicellulose – which decreases its hygroscopicity and thus increases its dimensional stability. Low oxygen content prevents the wood from burning at these high temperatures. Several different technologies use different media including nitrogen gas, steam and hot oil. All processes degrade strength and toughness of the treated lumber to some degree.