Thermowood is a thermal modification procedure that preserves wood in its most natural and flawless state for a life-long journey.
The first heat treated wood was produced in the 1930s by German scientists Stamm and Hansen and in the 1940s by American scientist White. Research was continued in the 1950s by Bavendam, Runkel and Buro. In the early 90s VTT (Technical Research Center of Finland) further refined the research into heat treatment, and developed Thermowood method.
“Thermowood method” involves heating wood material to temperatures of up to 180⁰C and preserving it with steam. Besides the preservation, Thermowood process also causes certain chemical changes in wood.
STAGES OF THERMOWOOD PROCESS
Drying; Temperature of wood is rapidly raised to 100°C. Following this rapid heating, temperature is increased steadily to 130°C, the wood is dried, and its moisture content is reduced to zero.
Heat Treatment; Temperature is increased to 180°C (for Thermo S) or to 212°C (for Thermo D) using steam. After the target level is reached, temperature remains constant for 2 to 3 hours.
Cooling and Conditioning; In the final stage, temperature is reduced to 80-90°C by water spray. This process continues until the moisture content reaches 4 to 6%.
NATURAL PRODUCTS TO AGE WITH YOU
The products treated with the Thermowood method are;
100% natural: The wood is free from resin and chemicals. No chemicals are used during the production process.
Ecological: Thermowood products contain no environmental or health hazards. They are produced from renewable forests, are environmentally friendly, sanitary, recyclable and durable.
Durable: Thanks to its low water absorption, Thermowood maintains its durability in all weather conditions. It is longer lasting than regular wood. Low moisture content also prevents decay and fungi growth.
Stable: Thermowood’s bending and twisting characteristics are reduced by %90, compared to ordinary wood.
Uniform: Heat treatment turns the wood into an uniform color. Compared to regular wood, Thermowood also keeps its varnish and paint better.
Insulating: Thermowood provides 25% more heat and sound insulation compared to regular wood.
Safe: Thermowood is 30% more fire resistant than regular wood.
Insect-proof: Thermowood is completely protected from insects due to its low moisture content.
WOOD IS DURABLE FOR A REASON
Heat treatment increases the stability and durability of wood.
Wood is composed of 50% cellulose, 23% hemicellulose, 20% lignin, and 7% other organic compounds, called extractives. Heat treatment removes resin, other extractives and their attached OH (Hydroxil) groups from the wood.
This process reduces water absorption of wood, consequently increasing decay resistance while decreasing swelling and shrinking. Another factor that contributes to the high durability of wood is the crystallization of cellulose. The change in hemicellulose increases the durability. Hemicellulose is separated into furfural and carboxylic acid. Caramelization of lignin, caused by heat, results in a darker color.