Wood is a popular building and finishing material. No synthetic substitute can compete with its useful and unique properties. Natural wood has an optimal balance of moisture and heat, it oxygenates the air, creates a unique microclimate and smells great.
To prolong the life of the wood a method has been developed to increase the resistance of lumber, beams, planks and other wood products to the external environment. The most effective way to preserve wood today is heat treatment.
Read more about the technology
The Finns are considered to be the pioneers of heat treatment of wood. They discovered a consistent pattern: birch, aspen, spruce and pine become less susceptible to external influences after being exposed to heat.
According to their research, the material must go through several stages during heat treatment:
- Drying at 130 – 150 °C in thermal chambers – the moisture content of the fibers drops to zero.
- Heat treatment – The wood hardens by increasing temperature (200-240 °C) and pressure, using water vapor. At this stage the timber acquires the color of a valuable species of wood;
- Cooling – The temperature is lowered by a water spray system to 80-90°C, and the wood moistens to a moisture level of 4-6%.
What happens to the material?
During the manufacturing process, the structure of the material changes at a molecular level. Fibers and bonds are split under temperature and pressure. The result is a surface that is moisture-resistant, resistant to warping, rotting, parasite infestation, and less porous.
Thermally treated lumber can withstand serious temperature changes, humidity spikes, and will no longer deform under heavy rains, even without additional protective coatings. Treated lumber does not rot, mold or insects do not grow in it, which means that it can last at least 20 times longer than conventional wood.
The new aesthetic characteristics of the material deserve special attention. In the process of thermo-hardening it changes color – it gets a shade peculiar only to the expensive varieties. So from the simplest material can turn out more valuable in appearance, for example, similar to larch.
Thermal processing depending on the temperature regime is divided into several classes:
1st – treatment of materials with low values and a light degree of tinting at temperatures up to 190 °C;
2nd – material is tinted to a darker color and acquires strength during drying at 200 °C;
3-rd – processing at 240 °C allows to get high quality and resistant to external factors lumber, hard and solid with the even dark shade with the noble texture.
Advantages of the material after heat treatment
- Resistant to temperature fluctuations.
- Categorizes as “eco”.
- The smell of real wood without extraneous impurities.
- A low drying rate.
- High quality of the surface.
- Uniform color shade across the entire cross section of the material.