The use of thermally modified timber has increased significantly worldwide over the past 25 years. Thermally modified timber products are natural, chemical-free wood products; they have long life cycles and can be recycled. 

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The custom of charring the surface of the wood to make it more moisture-resistant goes back to ancient Egypt. Thermal modification of wood in a kiln was first studied scientifically in the early 20th century. A major breakthrough in the field was made in Finland in 1993, when VTT, in collaboration with wood industry companies, developed the industrial-scale ThermoWood® process for improving timber properties with heat. At the same time, some other technologies were developed, such as the Plato Process (Netherlands), NOW (France), Thermoholz (Germany), and Westwood (USA). Today, thermo-treated lumber is produced worldwide in countries such as Finland, Sweden, Denmark, Belgium, Poland, Latvia, Turkey, Japan, Netherlands, France, Germany, China, Vietnam, Russia, Ukraine, USA, and Canada.  See the production growth in Europe based on ThermoWood technology in the last 20 years. In the USA, the demand for thermo-treated wood products has grown by 500% in the last three years.

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No chemicals are used in the production of thermally modified products. The production method is a result of extensive development work, and it is based on the controlled modification of timber with heat, steam, and water. The modification phases are high-temperature drying (200°F), thermal modification (400°F) in an oxygen-free environment with oxygen replaced by water steam, and cooling/conditioning with a water-spray system. 

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The process results in permanent physical and chemical changes in the wood on a molecular level. The product gains its brown color during the process when the heat changes its chemical properties. During thermal modification, wood secretes resin and other organic compounds and extractives, which are removed from the wood. The changes in the wood become irreversible and are a lifetime. During the thermo-treatment process, we burn poly-sugars and make wood water-repellent on a molecular level, which prevents the wood from rotting or decaying and makes it identical to 350-year-old lumber. Thermo-treated wood is naturally durable and stable for at least 25 years. The process is absolutely "Green" with no chemicals added. As a result, thermo-treated products are 100% “Green”.