Untreated wood is increasingly less used in construction. The difficulty in exploitation and the short life of the wood are the main reasons. But is it worth giving up the beauty and nobility of natural wood for the durability of the construction? Don't make a compromise. Thermowood is a modern building material that combines all these qualities.
Thermowood is widely used worldwide and is an excellent alternative to untreated wood. In Europe, there has recently been a ban on the use of wood without thermal treatment in the open air, specifically for the purpose of preserving wood. The technology of making thermowood consists of processing various wood species and produced using chemical-free heat treatment in a superheated steam environment. Pay attention to the wood that the company "Twood" works with: Siberian larch, ash, birch. These are the wood species that we subject to thermal treatment and then manufacture products of different profiles and purposes.
During processing, the resin is removed. "Live wood" changes its molecular structure, getting a saturated dark color and new qualities.
The company "Twood" works only with high-quality materials because we know how important is a high service span of finishing. We offer thermowood - a modern finishing material, that has a beautiful natural pattern, simple processing and affordable price.
Kiln drying with special preservatives have been invented to expand the application of wood. However, chemical treatment has reduced the environmental and safety of wood. This is why heat treatment is becoming more popular worldwide. During heat treatment, only superheated water steam and high pressure are used without any chemicals.
Thermal treatment creates new properties of wood to use it for finishing rooms with high humidity, finishing exterior building facades, building gazebos, making parquet, finishing saunas and baths.
Dried wood is placed in special chamber kilns, where it is treated with steam under high pressure. The temperature at the beginning is 70-100 °C, and then it is raised to 170-200 °C. During this stage, the wood is going through thermohydrolysis, a process of interaction between polysaccharides in the wood and water. Next, the steam temperature is lowered to 90-100 °C and the wood conditioning, bringing its moisture level to 4-5%, which is optimal to use thermowood in finishing. Finally, the wood is cooled to a temperature of 30-40 °C. On average, the thermal treatment process takes about two days.
Thermowood demonstrates strong structural integrity and long-term durability. Thermowood is resistant to moisture, rot, insects, and fungal growth, which allows it to last for decades without losing its original appearance.
Protecting structures and wooden elements from mold, fungi, and pests should begin at the earliest stages of construction. Wood protection methods can be divided into chemical and physical.
It is necessary to remove any moisture present in it to protect wood from pests. Harmful microorganisms typically decompose wood with a moisture level of 28-30%. The first defense against mold and fungi is drying. The best moisture content is 12-16%.
Chemical protection of wood against mold is the second stage. During this stage the wood is treated with antiseptics and fungicides. Both types of chemicals make an environment unsuitable for the life and development of parasites. Antiseptics are agents that have the highest activity against pests and mold. They are broad-spectrum chemicals. Fungicides are agents that protect wood from fungi. They help stop the growth of fungi at the infection stage. Fungicides preserve wood at the microstructural level.
Currently, manufacturers add both types of agents to paints and varnishes. There are also various pastes available. If such paint and varnish products are used, it is possible to decorate and protect wooden structures at the same time. The easiest way to treat wood is through local impregnation. This method involves applying antiseptics and fungicides to the surface of the wood with a brush or spray. This method of protection against pests only protects the top layers of fibers. A barrier on the surface will lose its strength over time.
A more complex method of protecting against mold and fungi is immersion treatment or treatment with special agents under pressure. The idea is to deliver the protective composition as deeply as possible into the structure of the wood cells. After such treatment, the entire mass of wood becomes unsuitable for the development of pests. Industrial methods of wood protection are the most long-term and effective. It is the only way to make an even distribution of protective compounds. Also additional decorative protection of wood with paint and varnish protective agents can be done at the same time. Surface protection of wood against pests is the easiest, cheapest, and most effective method. However, the surface protective layer should be constantly renewed.
The first use of temperature to change the shape of wood is known since ancient times. This method was used in the production of wooden utensils and dishes. Initially, the wood was boiled in oil, giving it necessary properties that could not be achieved if the product dried naturally. The wood became hygroscopic and retained its shape well, while also being resistant to decay.
Many peoples attempted to improve the properties of wood. For example, the Vikings subjected it to fire to prolong its lifespan, while Germanic tribes and Slavs boiled and soaked it. Native Americans burned the tips of their spears for greater durability. The processing of wood is exemplified by the mill wheels we all know, which Don Quixote so vigorously fought against. Woodcarvers know an excellent way to quickly dry lime wood by boiling a log in water and wrapping it in a dry towel and old newspapers, then placing it near a hot radiator. However, the first scientific attempt to process wood was made in Germany and then in the 1940s in the USA.
In 1987, in the Novy Urengoy city, the traditional method of wood processing was adopted for furniture production. After developing a scientific technology based on this method, they began producing furniture. Attempts to make wood processing more technologically advanced did not stop. It was also desired to give the product a better color tone.
By the mid-90s, the most advanced method was drying wood at a very high temperature of up to 150 degrees Celsius. And in 1997 in Finland, thermal treatment up to 230 degrees Celsius was applied for the first time. Quality and production volumes began to represent a product called Thermally Modified Wood (TMW). TMW has gained widespread use in Europe.
Several wood processing technologies are known:
1. Steam-stabilization. This technology is used in France. Processing is carried out at a high temperature with unsaturated water vapor.
2. Treatment at high temperature in a steam atmosphere. Used mostly in Finland.
3. Cyclical hydrothermal treatment. Applied in the Netherlands.
4. Drying in organic liquids. Various oils are used. Used in Germany.
5. Russia, Canada, and other European countries use a mixed technology.
The leadership in the processing and sale of TMW belongs to England, France, Finland, and Belgium. Attempts are still being made to find new ways to process wood.
Comparison of thermally treated wood and natural wood:
— After being treated at high temperatures, the weight of the wood decreases by 0.5-10%;
— The service life of thermally treated wood exceeds natural wood by 25 times;
— After thermal treatment, the strength increase due to compression is over 50%;
— The equilibrium relative humidity is approximately 50% lower in natural wood, with a fluctuation range of 3-5%;
— The dimensional stability of thermally treated wood is up to 15 times higher;
— Natural wood absorbs three to five times more excess moisture;
— The thermal conductivity properties of thermally treated wood are up to 25% lower;
—Natural wood ignites at a temperature of about 60-80 degrees lower than thermally treated wood;
— The downside of natural wood is that it is not protected from damage caused by insects and is susceptible to fungal and other microscopic life forms;
— Thermally treated wood does not deform under environmental conditions and can be used both indoors and outdoors due to its water-repellent properties;
— The color palette of natural wood is less diverse and the color is less smooth and saturated;
— The process of thermal treatment does not involve the use of chemical compounds, which indicates a lack of harmful effects on human health and the environment;
— Thermally treated wood is easy to maintain due to its inherent moisture resistance and strength properties. The only preferred maintenance condition for products made from this material is to coat them with specialized eco-friendly varnishes or paints that provide protection and aesthetic effect.
Based on the comparative analysis, it can be concluded that thermally treated wood predominantly leads in all criteria. This is why it has the highest demand in the construction materials market.
All types of wood are prone to "sunburn" due to prolonged exposure to sunlight. Thermowood is a vivid example of this. Such changes are explained by the fact that under the influence of ultraviolet radiation, the upper layer of lignin is destroyed, which leads to the formation of hairline mini-cracks. Various bacteria and microorganisms penetrate through the cracks and cause the board's natural color to change to gray-silver. Such changes do not spread deeper than the upper layer. This fact can be easily confirmed, all you need is just to scratch the surface and the wood's natural shade will be revealed. The disappearance of the gray shade is also observed when the material gets wet.
It is clear that thermowood can only change its initial appearance at a depth of 0.1-0.2 millimeters. Further penetration of microorganisms is excluded, since the internal environment of the board does not have sources of nutrition for microorganisms.
According to German scientists, wood that is exposed to the open air burns out by 0.05-0.1mm per year. The reason for this is the absence of a protective coating. Usually, such changes become noticeable after 5-6 years. At first lignin weathers, which leads to the opening of solid cellulose. As a result, the surface turns into a rough structure. This is why wood is often treated before outdoor use in Europe, making it rough and brushed. Brushing is the process of removing soft layers of wood.
To avoid external deterioration of the wood surface, it is highly recommended to regularly care for the coating and renew it in accordance with recommendations. There are a huge number of special protective agents for this purpose.
