Thermowood (heat-treated board) is a unique type of wood panels that has rapidly burst into the construction market and has taken a leading position among finishing materials made from natural wood. Thermowood is distinguished by improved characteristics and an expanded area of use.
Thermowood production is characterized by the process of heat treatment of coniferous and hardwood blanks. Most often, oak, ash, pine and, less often, spruce become the basis for manufacturing.
Prolonged exposure to the temperature to which thermowood is exposed makes it hollow. The manufacturing technology is quite simple in the sense that during processing the wood is deprived of cellulose and resins.
At the same time, the structure of the wood fiber changes and is modified into a kind of caramelized mass, which determines high operational properties.
Manufacturing includes the following steps:
- Drying of workpieces. The stage takes place in a special vacuum box, where air is pumped out and slowly warmed up to a temperature of + 180 ° C. This stage is characterized by the formation of steam in the chamber.
- Processing of workpieces, or the so-called increase in biostability. The steam generated at the first technological stage is enriched with chemical reagents. In this case, the boards are exposed to high pressure, which, in combination with reagents, promotes the decomposition of cellulose fibers. That is, there is a molecular change in the structure of wood. As you know, it is hemicellulose that becomes a breeding ground for the growth of fungi and mold - such a possibility is excluded in thermowood.
- Stabilization of workpieces. The stage is characterized by crystallization of cellulose fibers.
https://youtu.be/vEcoPOCkTyw
Heat treatment of wood can be carried out using four technologies:
- Processing in one step. With this method, the workpieces are processed with heated steam at a temperature of 150 ° to 200 ° C, under the influence of which the oxygen content of the box decreases to 3.5%. Both pre-dried and green blanks can be subjected to one-stage processing. Processing dried wood takes about 3 days, and raw wood - a few days longer.
- Multi-stage processing under the influence of heated steam and pressure. It takes place in a sealed box at a temperature of + 150- + 200 ° C and a pressure of at least 1.6 MPa. Drying is carried out within 4 days. The moisture content of finished products should not exceed 10%.
- Processing with vegetable oil. The technology provides for placing blanks in containers filled with vegetable oil and slow heating. At the same time, the structure of the wood is saturated with a small amount of oil, which makes the thermowood moisture resistant and resistant to cracking.
- Nitrogen treatment with 2% oxygen or other inert gas. The process is called re-certification. This technology allows us to obtain products of the highest quality.
The great demand for construction and finishing materials made of wood is associated with the purity, environmental friendliness and good qualities of wood. In recent decades, other raw materials have been actively developed that are not affected by moisture, deformation, decay and other defects. However, synthetic products often pick up the useful properties of wood, therefore, developments to find new ways to increase the durability and qualities of natural materials continue now. The pinnacle of hardening beams, boards and other sawn timber is the heat treatment method.
Wood heat treatment technology
For the first time, a method of heat treatment of wood appeared in Finland. It was the inhabitants of this country who discovered an increase in the resistance of the material to atmospheric influences as a result of heat treatment of birch, if, pine and aspen.
According to their methodology for the process, it is necessary to conduct the material through several stages:
- Elimination of moisture from timber fibers by drying in closed chambers at temperatures from 130 ° C to 150 ° C.
- At high pressure using water vapor, the thermal hardening of sawn timber continues at temperatures from 200 ° C to 240 ° C. At this stage, the wood is colored in a characteristic shade.
- Lowering the temperature with bringing the percentage of moisture content in the fibers to a level of no more than 4-6%.
As a result of this finishing cycle, the timber has a new texture, altered at the molecular level. This is due to the splitting of the fibers and the bonds between them, as a result of high pressure and temperature. Thus, the surface becomes less porous, it is able to withstand moisture, less responsive to deformation under heavy rains, and does not require additional protective coating. Also, a thermal tree can boast of transferring high temperature fluctuations and moisture jumps by 10-15 times.
The color of the wood after such treatment becomes close to the shade of expensive varieties. Even with the simplest cheap piece of wood, you can make a material similar in appearance to larch or other expensive species. The change in structure increases resistance to decay, mold and insect infestation, which increases the service life of wooden elements by an average of 20 times compared to their natural counterpart.
Thermowood benefits
- Environmentally friendly origin.
- Smells like wood without third-party fragrances.
- Withstands significant temperature changes.
- Has a low percentage of drying out.
- Long operational life.
- The surface quality is very high.
- The entire cross-section and longitudinal section of the material has the same tone, corresponding to the external color.
Due to the significant spread of the temperature regime of timber processing, there are the following classes of thermowood:
- Class 1... Material with the lowest performance and the lightest degree of toning, due to processing at temperatures up to 190 ° C.
- Class 2. Timber gets high strength and resistance to decay with a darker color, but fragile and less ductile due to processing at 210 ° C.
- Class 3. The highest quality sawn timber with high resistance to aggressive environmental influences, hardness and density. They have a uniform dark shade and a noble surface texture. Produced at 240 ° C.
Heat treatment equipment
There are many manufacturers of thermal wood equipment that use different technologies for the process of firing specific types of wood. The most popular brands are:
- Vacuum Plus;
- Bikos-TMT;
- Fromsseier;
- Menz-Holz;
- Retification;
- PLATO;
- Thermowood;
- Westwood.
Differences and features of thermal chambers
| Technology / company name | Operating temperature range | Duration of one cycle, hours | Country | Tree species |
| Vacuum Plus | 45 for vacuum drying, 165-190 for heat treatment | 3-7 days | Russia | everything, due to vacuum drying |
| Bikos-TMT | 180-220 | 38-52 | Russia | soft conifers, valuable hardwood at the exit with an uneven shade |
| Fromsseier | 180-220 | 2-3 days | Denmark | soft conifers |
| Menz-Holz | 180-230 | 32-54 | Germany | all thanks to the introduction of organic oils into the steam |
| Retification | 180-220 | 40-62 | France | everything, due to the use of nitrogen in steam |
| PLATO | 170-210 | 5-8 days | Holland | birch and conifers |
| Thermowood | 180-215 | 45-96 | Finland | soft conifers |
| Westwood | 220-240 | up to 48 | USA | valuable hardwood: beech, oak, ash |
Heat treatment chamber
The equipment is a tightly closing tank of a certain volume, into which lumber is loaded on special stands. It is necessary to ensure the possibility of steam access to all surfaces of the board or timber. During the processing cycle, depending on the technology in the chamber, the material is dried at high temperatures, evacuated or inert gas, organic oils, fired at extreme temperatures and moisture correction.
Each heat chamber must be characterized by the following parameters:
- The level of security and the specifics of managing the operation of the device.
- The permissible level of moisture content of the feedstock.
- The duration of the full cycle (depends on technology, wood species, method of preliminary processing of sawn timber).
- Allowable dimensions of the cross-section of the timber, at which the raw material will receive a uniform color throughout the entire thickness.
- Energy consumption and other required resources for the heat treatment process.
- Overall dimensions and volume of the working area, which makes it possible to increase the amount of wood processing in one cycle.
Heat treatment of wood at home
The creation of a heat chamber by a handicraft method implies the presence of the following components:
- A tight-fitting container that will not allow oxygen to get inside during heating.
- Energy supply method: electric, gas or solid fuel heating of the chamber cavity.
- Containers with water to create the desired level of humidity inside the work area.
- Tools for working with metal, electrical and gas equipment.
The principle of operation of the device is to introduce a container with water into the chamber, which will evaporate as a result of an increase in temperature, preventing the ignition of lumber in the mode from 135 ℃. The chamber must be heated so that the required high temperature is set inside. Most often, an electric heating method is used for this. The ingress of oxygen increases the risk of wood fire, therefore the chamber must be securely and hermetically closed.
An example of such crafts can be found on all kinds of forums of folk craftsmen. Some present their creations from railway tank cars with complex internal structures for the installation of materials. However, at home, small pieces of wood can be processed differently. It is enough to boil the workpiece for about an hour and a half in ordinary water, and then wrap it in warm old clothes or newspapers. In this form, continue drying near a stove or other heat source. This method has been used by woodcarvers for many hundreds of years to harden the linden.
Conclusion
Thermowood is still a material of natural origin, as evidenced by even its smell. For the external surface, the material does not require additional finishing and coating. Differs in high resistance to precipitation and temperature extremes, which allows you to start a new era of wood in human housing. Most importantly, thermowood windows and doors will serve for more than a dozen years without losing quality and appearance.
One of the progressive directions in the development of building technologies is the development and implementation of new materials with high performance characteristics. Thermo wood belongs to such new products. She is endowed with positive characteristics, which include the following parameters:
- natural base;
- super-resistance to the influence of the external environment;
- no need for additional processing with aggressive chemicals.
Such properties make the process of thermomodification of wood and its result quite popular for various fields of application. For example, durable thermo-wood windows are already appearing on the market. 
Production stages
Thermowood is produced in Moscow or another city using special equipment. At the same time, no additional components are provided by the production technology. Heat treatment of wood is carried out by the action of water vapor on the raw material, placed in a sealed chamber. Blanks are made of oak, ash, beech, walnut, less often pine.
Initially, the modern wood heat treatment technology was developed by Finnish specialists. Prepared raw materials in a closed module in the absence of oxygen access are exposed to multi-stage exposure to steam heated to 185-212 C.
Such a progressive heat treatment of wood began to be used not only in Europe, but also in Canada and on the territory of Russia. The following steps are involved:
- Heating the workpiece. First of all, the equipment for thermowood heats the material placed inside to 13-150 C. Then, the wood is exposed to steam by the method of cooking for 5 hours.
- Drying. Heat-treated sawn timber is dried, reducing the moisture content of the raw material to 10%. Thermally modified wood in the drying equipment remains for 2-3 days to achieve optimal parameters.
- Excerpt. In closed conditions, the temperature is raised and saturated with water vapor at an increased pressure. This process of thermally modified wood technology gives the material's characteristic hardness and unique color. The palette changes depending on the thermal mode, and not on the duration of processing. The resistance to external effects of moisture increases, putrefactive phenomena are excluded and further deformation does not occur.
Technology features
It should be borne in mind that the mode at 190 C will only provide a decorative effect, without significantly affecting the operational characteristics.
In most cases, heat treatment is carried out in a mode of 200-230 C. Thus, the resistance to decay increases several times. This material can be used in the production of furniture, decor, window frames, interior doors.
The price of thermally modified wood, which has been exposed to more than 230 C, will be higher, as its properties will noticeably improve. The board will receive resistance not only to rotting, but also to swelling. As a result, the material can be used for almost any outdoor work or aggressive environment, for example, in swimming pools, saunas, baths, etc.
In Germany, heat treatment of wood, the prices of which fluctuate depending on the type of wood, the technology used and can range from 25,000 rubles. up to 80,000 rubles. per cubic meter, carried out in an oil environment. A dry edged board is placed in oil at 180-220 C, holding for 3-4 hours.
How to make a thermal tree with your own hands is presented in the video.
There is also a technique for treating boards in inert gases and nitrogen atmosphere at elevated pressure. The oxygen level should not exceed 2%.
Comparative characteristics of technologies for thermomodification of wood are presented in the table.
Is it possible to dry a timber to a moisture content of 6% in 72 hours and obtain a thermal timber with a section of 300x300 mm? Wood drying experts say no. But in the research and production association "Pobeda" they claim that this is possible - when using a camera developed at NPO for modifying wood. Oleg Shulman, General Director of the DrevTermo Trading House (co-founder of Pobeda NPO), told the correspondent of our magazine about the peculiarities of the operation of the heat chamber.
- Oleg Isaakovich, please tell us why you decided to develop equipment for heat treatment?
- The Russian consumer has been familiar with thermowood for more than 15 years, and every year the scope of its application is expanding. Thermowood has established itself in the domestic market as a modern material for exterior and interior decoration of houses, saunas and baths, as a material for the manufacture of floor coverings, coverings for terraces, patios, garden paths, areas near pools, stairs, interior items, and garden furniture, landscape design elements and fences. We analyzed the existing heat treatment technologies (Bikos-TMT, Vacuum Plus, Mirako, Fromsseier, Menz-Holz, Retification, Plato, Thermowood) and came to the conclusion that their main disadvantages are increased requirements for the quality of raw materials (wood must be at least the first varieties) and high energy consumption (the duration of heat treatment can take up to 20 days). None of the technologies used can be used to obtain a thermally modified timber or a log of low cost in a short time.
A few years ago, in our country, they began to produce a thermo-beam. Enterprises of wooden housing construction are interested in this material. Taking into account the popularity of thermomodification technology in Russia, our research center conducted a survey of house-building companies, which confirmed the demand for heat-treated timber or logs, as well as the desire to produce them at our own production facilities.
- What is the peculiarity of your technology?
- The technology developed by the engineer of our scientific center Oleg Moichkin, in comparison with those that are widespread now, has differences in the methods of heating wood and removing moisture. The heat treatment modes are worked out in such a way that it is possible to use raw materials with a moisture content of up to 100% (freshly cut), no preliminary drying of wood is required before heat treatment. Thermal modification is carried out in just one cycle, its duration depends on the breed and size of the processed material, and according to existing technologies, heat treatment is performed in several stages. Reducing the duration of heat treatment allows you to reduce the cost of electricity to 1200 rubles / m 3. According to existing technologies, the minimum costs for energy resources are 5000 rubles / m 3.
According to the laws of thermodynamics, heat treatment of 1 m 3 of wood requires at least 250 kW of electricity. The processes occurring in the chamber cannot be described by these laws, since the efficiency of our camera approaches 200% (according to existing technologies, the efficiency of the camera does not exceed 80%). Based on the results of studies of the structure of electrical matter by the scientist Yuri Rybnikov and his periodic table of electroatoms, the result is quite understandable.
- Is your technology analogous to the one presented on the market by Thermowood?
- Finnish Thermowood technology cannot be compared with ours: they are different. The study of methods of wood processing and drying has been carried out for a long time. But in fact, the processes that describe a particular physical process, in practice, cannot be reproduced with 100% accuracy. The classification of types and methods of drying is usually based on methods of heat transfer. In our heat chamber, wood is simultaneously processed with infrared radiation, convective and conductive drying. Energy consumption is minimal due to the fact that no electricity consumption is required to start or end one of the heating processes. Thermal modification of wood takes place in a superheated steam environment. In the process of heat treatment, the wood acquires a rich noble brown hue, uniform throughout the section. After thermal modification, the material can be immediately machined and coated with paints and varnishes.
- Under what conditions does the timber heat treatment take place?
- At the moment, the modes of thermalization have been debugged to obtain thermo-beams from birch, pine, spruce, linden and aspen wood. For processing aspen wood, it is necessary to take into account more parameters than for other wood species, in order to reduce internal stresses in the resulting material. It is better to heat a bar with a section of 300 × 300 mm at a temperature of 160-170 ° C for 72 hours. With this mode, the strength of the wood for bending and chipping is slightly reduced. The high processing temperature (180-200 ° C) makes it brittle, it also darkens strongly, which impairs its aesthetic qualities. The processing of wood of the above species takes different times, but the difference is only a few hours. In addition to the thermo-beam, the chamber is designed for processing rounded logs (up to 30 cm in diameter) and sawn timber. The volume of a one-time loading of the chamber is 5 m 3, after processing the volume of finished products is 3.5 m 3.
- For the industrial production of house kits, the chamber with a volume of 5 m 3 is small. Are you planning to increase its size?
- Since the ongoing processes cannot be described using mathematical algorithms, and when creating a large-volume chamber, it will be necessary to work out the modes of thermal modification, the parameters of which will be calculated taking into account the large volume of processed wood. We are already working on the creation of chambers with a volume of one-time loading of 10-12 m 3 and 20-25 m 3.
- How are camera modes controlled?
- Now the camera is controlled by the simplest automation, and the heat treatment mode is adjusted manually. With an increase in the size of the chamber, all processes will be fully automated. It will be enough for the operator to set the necessary parameters before loading the raw materials, close the chamber, and after the completion of the process, unload the heat-treated materials.
- How is the camera installed in an existing enterprise for the manufacture of prefabricated wooden houses?
- The camera can be easily and quickly integrated into the existing technological process. If a company is engaged in the manufacture of house kits from profiled beams, then additional areas will be needed to install the camera, and the machines that are in the production for processing profiled beams can also be used to process thermally modified material. There are no restrictions. The production of a new type of product - thermobeam - allows you to expand the range of products manufactured by the enterprise and does not create any difficulties in work. In its price segment, thermally insulated beams or logs will compete with glued beams, and in the construction of wooden houses from profiled beams they will replace the latter.
- You said that the enterprise will need additional space only for the installation of the camera. Which ones?
- A chamber with a loading volume of 5 m 3 occupies about 9.5 m 2, its length is 6.7 m, width and height - 1.5 m. For an industrial enterprise, this is a small area.
- Substances that are released from wood during heat treatment are environmentally unsafe. How is the issue of disposal of waste arising in the process of wood modification resolved?
- Our chambers are equipped with special recycling systems, so no harmful substances are emitted during the heat treatment, which indicates the environmental safety of the process.
- Usually, after high-temperature processing, the wood acquires a burning smell. Does your thermal beam or thermal log have it?
- The products of pyrolysis, which are formed during the thermal modification of a bar or log, are removed during processing, which makes it possible, after heat treatment, to immediately carry the material to the construction site, and not to keep it in the warehouse to remove odor.
- What will be the characteristics of the building material after heat treatment?
Thermally treated birch wood products
Thermal birch souvenir
- Thermal beams and thermal logs have the same characteristics as thermal boards and thermal lining: stability of geometric dimensions, increased hygroscopicity, biological resistance, low thermal conductivity, environmental safety, aesthetics.
If we are talking about thermo-beams, then this product is a substitute for profiled beams of natural moisture. Heat treatment allows to reduce the construction time to three years: the moisture content of the thermobeam is about 6%, so there is no need to assemble the walls of the house and then wait for them to shrink. The increased biostability of the timber after heat treatment excludes the treatment of the walls of the house with compounds that protect the wood from damage by microorganisms or insects. As I said earlier, low energy costs provide a reduction in the cost of finished products, which allows you to reduce the cost of building a house from solid wood by up to 30% when compared with the cost of building a house from laminated veneer lumber.
A beam with a section of 300x300 mm is laid in the heat chamber, and after machining its section will be 260x240 mm, the effect of an elevated temperature on the wood makes it possible to reduce the thermal conductivity of the material and increase the thermal insulation characteristics, which are its advantages over glued beams.
After heat treatment, the geometric dimensions of a bar or log do not depend on variable temperature and humidity conditions (for example, atmospheric precipitation). Therefore, you can build a house at any time of the year. In accordance with the results of preliminary tests carried out by our specialists, the thermal characteristics of a house made of a thermo-beam or a log are 20-30% higher than the thermal characteristics of a house made of glued or profiled timber.
Due to the fact that the modern construction market is flooded with synthetic materials that are not distinguished by their environmental friendliness, the demand for natural materials that can be used without fear for their health has increased. First of all, this is wood, which is very far from ideal due to its inability to withstand natural factors - we all know how it behaves in a wet and dry environment, how insects and microorganisms such as mold love it. In general, in outdoor conditions, without proper protection, a tree does not serve for a long time. It's a pity. Strange as it may seem, modern technologies have come to the rescue here as well - relatively recently such a method of wood processing as thermal modification has appeared. The end product of this technology is thermowood, which we will talk about in this article. Together with the site, we will study in detail the building material of this type.
Do-it-yourself thermowood photo
Thermowood: what is it and how is it produced
The process of making thermowood is quite simple - in fact, it is subjected to prolonged exposure to temperature, as a result of which it becomes empty. In the sense that cellulose partially burns out in it, all available resins come out and the structure of the fibers themselves changes - the tree seems to be caramelized, due to which it acquires very high performance, because of them it is valued. Heat treatment of wood can be done in four different ways.
What is the result of all these types of processing? What properties give it in this way? But with this moment we will figure it out further.
Facade thermowood: characteristics
The most important feature inherent in thermal wood is its dimensional stability, which cannot be influenced by moisture or temperature - it practically does not absorb moisture. What does it mean? Neither more nor less, but the fact that over time the same one, trimmed with this material, will not lose its original appearance. But this is not all the advantages of thermowood - along the way, in the process of processing, it acquires other useful qualities. By the way, they are also useless, but more on that later.
And all this against the background of exceptional ecological purity, which is so appreciated by modern people - this material in the process of exposure not only does not fill with chemicals, but it also removes all substances that may be harmful to human health. As for the shortcomings, then, according to the manufacturers, thermal wood has only one - fragility. Not the same as glass, but nevertheless, if you compare this figure with standard wood, it is high. Processing, in particular, sawing of this material, must be carried out at high speeds with low feed and a tool with a fine tooth - otherwise the thermal wood will burst.
Thermowood and its processing class
Thermowood is produced under the influence of superheated steam at temperatures from 150 to 240 degrees Celsius - the expansion is large, but it is this that determines the division of this material into classes. There are three of them.
Naturally, depending on the processing class, the cost of the material also changes - the higher it is, the more expensive the material is. So you should think three times what qualities you need.
Thermowood board: scope
By and large, the scope of application of thermowood is not limited - it can be used wherever a modern person uses ordinary wood. There is, however, one nuance that must be taken into account before deciding on its application - this is the cost. The price of thermowood is very high, and in most cases, the cost of purchasing it may be impractical. For example, it can be used indoors, but it is expensive - with the same success, ordinary wood is also suitable for decoration. This material has its own field of application, in which the costs for it are justified.
In general, here you should think carefully about the advisability of using thermowood - perhaps you will come to the conclusion that it will be much cheaper to create a conventional imitation of this material, which is not so difficult. By the way, this is a reason to think about the question, do you buy thermal wood in the store? There are many ways to make wood look like this material. You understand that this is only a view, but not qualities.
And in conclusion of the topic, I will say a few words about the question, can thermowood be made by hand? It is, in principle, possible to make it in small quantities and fragments of small size - for this you need an electric oven with the ability to adjust the temperature. In addition to wood, it will be necessary to install a container with water in it - without saturation with steam, the tree can catch fire.
There is nothing more to add about this material. It remains only to take stock and draw conclusions for yourself. The material is, of course, expensive, but spending a lot of money on it, you can be sure that products made from it will delight your eye for a long time. We can say more - they will be inherited by your children in a practically unchanged state.
The impact of high temperature on wood changes its properties, making the material more resistant to negative natural factors and mechanical stress. As a result of the study by scientists of the modification of wood, a new material appeared - thermowood. The first method was invented by the Finns. It consisted of preliminary drying and heat treatment of the material without the addition of chemical additives. But it is impossible to do without chemistry completely. The fact is that thermowood acquires a grayish tint from exposure to ultraviolet rays. Chemical blockers help to maintain the beautiful color of the material.
To produce the material, wood is heated to 140-270 ° C. The maximum heating temperature depends on the density of the wood. Partial combustion of xylose in drying chambers changes the quality of the material. High temperature expels resin from conifers.
The thermal tree acquires a caramel color and equilibrium moisture content. Not only the external, but also the internal structure changes, therefore the cut point of the processed board has the same color, has the same strength as the surface. Heat treatment is combined with water treatment, which leads to hydrolysis of the wood components.
The floor on the veranda made of thermowood is not afraid of humidity and temperature changes
Thermowood is now produced using four methods:
- The one-stage method of steaming takes place in special units similar to drying chambers. The technology provides for the supply of steam, which reduces the oxygen content of the chamber to 3.5%. In wood heated to 150-200 ° C, oxidation slows down. Pre-dried wood is processed for about 3 days. Heat treatment of raw wood takes more time, taking into account drying.
- The multi-stage method resembles a cooking process. The technology consists in wet processing of wood with steam or water. Cooking takes place at a temperature of 150-200 ° C in a sealed chamber under a pressure of 1.6 MPa. Then the material is dried for about 4 days in a chamber until a moisture content of 10% is reached. At the onset of the hardening phase, the wood is heated for 16 hours to a temperature of 170-190 o C.
- Another hot working method involves dipping dry wood in oil. The process takes about a day. The oil is slowly heated for about 4 hours to a temperature of 180-220 o C. During the entire heating period and until it cools completely, the wood absorbs oil.
- The method of treatment with inert gases is called retification. The technology provides for the treatment of wood with nitrogen with 2% oxygen under pressure.
Exterior decoration of the house with thermowood
Processing class
Thermowood is produced at different temperatures. It is this difference that divides the material into three classes:
- Thermowood of the 1st class is produced at a temperature of 190 o C. The material has low technical characteristics with little color change;
- the material of the 2nd class is obtained after processing at a temperature of 210 o C. Thermowood becomes strong and resistant to decay. At the same time, it loses its plasticity, becoming more fragile. The color of the material of the 2nd class is darker than that of the previous one;
- the highest class of wood heat treatment - 3rd. Thermowood after firing at a temperature of 240 ° C acquires a high density, becoming more resistant to negative natural factors.
Thermal tree in the decoration of the area near the pool
Material characteristics
Heat treatment gives wood many positive qualities:
- dimensional stability is the main positive quality that a thermal tree is endowed with. The material will not change its appearance from the influence of many negative factors. Thermowood, unlike ordinary wood, does not change its shape from moisture, because it has an equilibrium moisture content close to zero and does not absorb steam;
- an important indicator is the long service life and strength of the material. Heat treatment increases the service life of wooden boards up to 20 times. Polysaccharides are partially decomposed from the high temperature in wood. The resulting protective qualities prevent the development of mold and the appearance of insects;
- thermal wood is highly resistant to fires. Dry natural wood instantly ignites. The modification process has reduced the risk of material ignition to a minimum;
- the aesthetic appearance of the material allows you to introduce original design ideas. Thermowood is similar in structure to the elite species of tropical trees, surpassing them in durability.
Garden path from thermodecking
Application area
Thermal wood is used wherever ordinary wood is used. This is a very expensive material and you just need to make the right decision about the appropriateness of its use. For example, inside a building it is cheaper to decorate walls and floors with ordinary wood. Such an expensive material is used where it justifies its costs:
Thermal wood bathroom
Self heat treatment of wood
Many enthusiasts are interested in how you can do the heat treatment of wood yourself at home. In fact, this is a complex production. On the forums you can find inventors who made a drying chamber with their own hands from a railway tank with a capacity of 15 cubic meters. m. The main production condition is the complete tightness of the chamber. Otherwise, the presence of oxygen will contribute to the ignition of wood during heating above 135 ° C. And steam will be required.
The simplest DIY method of heat treatment is to boil a small piece of wood for 1.5 hours in water. Then wrap it in a cloth and old newspaper, put it near any heat source to dry. This method is used by woodcarvers to dry linden.
Although heat treatment of wood gives it many advantages, it is nevertheless necessary to treat a thermal tree with a special waterproofing compound. These are natural and synthetic oils with additives. They are selected depending on the type of wood, color, place of use of the material.
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The consumer has played enough with modern materials, and the "sterile" plastic renovation has set many people on edge. To dilute the refined style of trendy coatings, some wood furnishings and furnishings need to be aged. We will show you how to give the wood an antiquity effect at home.
Antique wood processing allows you to create the effect of vintage furniture and a luxurious interior.
Features of the method
The photo shows an example of aged garden furniture.
Before processing a semi-antique wood, it is advisable to study and understand the methodology of this process. We are faced with the task of imitating the natural aging of the material, so let's figure out what exactly happens during this.
The wood is heterogeneous and consists of many layers, which are visible on the cut in the form of the so-called annual rings. These layers are formed during the growth of the plant.
And due to the fact that this growth occurs in different temperature and weather conditions (from year to year there are noticeable fluctuations in weather and temperature indicators), the density and strength of the layers differ significantly.
Wood consists of many layers of different density.
During the operation of the material, it is exposed to a number of different destructive factors, including erosion under the influence of precipitation, wind, solar radiation, etc.
Since the layers have different strength and density, they break down unevenly:
- softer faster;
- more durable - slower.
As a result, the surface of the material acquires a characteristic relief, which distinguishes old wood from young. In addition, the fibers change color: some darken more, others turn yellow, some layers remain light. This is how the patina appears.
With aging, relief and patina appear.
Thus, we are faced with the task of achieving a similar effect, namely:
- Expose the material to such an effect, as a result of which the destruction of the layers of wood will occur, which, taking into account the inhomogeneity of their physical characteristics, will lead to the appearance of a relief. Of course, this must be done in an accelerated mode compared to natural erosion;
- Give the surface a color similar to the natural discoloration caused by prolonged exposure to the environment. In other words, we have to make an artificial patina.
Board after artificial processing.
There are several ways to simulate the natural erosion of a material:
- Mechanical restoration. With abrasive tools such as metal and nylon brushes, an aging-like relief can be created;
- Heat treatment. Helps to create relief and change the color of the fibers. Blow torches and gas burners are used;
- Chemical processing. Strong alkali solutions erode cellulose, creating uneven degradation in different layers.
Patination is carried out using various oils, paints, wax and wood stains. Next, we will show you how to paint antique wood with the simplest tools.
Patination with wax.
Important: The price of semi-antique furniture and lumber is very high, and with the help of our guide, you can create them yourself from the most common wood.
Antique wood processing
Mechanical
Mechanical processing is the most effective way of aging.
Mechanical aging is called wood brushing, from the English word "brush" - "brush". Accordingly, an abrasive brush should be used for work.
Roughing with a grinder.
The process consists of three main stages, which are revealed in the following table:
Sanding with a nylon brush.
Important! First, you should practice trimming the board in order to understand the nuances of the process, feel the pressure and choose the right abrasive caliber.
Thermal and chemical
A piece of timber after firing.
Another popular way to give wood an antique look is by firing. Since the layers of the material have different physicochemical characteristics, as a result of exposure to high temperatures and flame, they burn out with different intensity.
It is best to use a gas burner for the job. Gasoline blowtorches smoke heavily, which can add extra work to us.
Sufficiently inexpensive Chinese burner with a cylinder.
So let's get started. We take the board and begin to burn it with the flame of a gas burner. We make sure that the material does not flare up, but evenly charred over the entire surface.
The degree of charring is selected individually depending on the type of wood and the desired effect. Typically the surface is finished to an almost solid black color.
The photo shows the approximate degree of charring.
After the board has cooled down, it is sanded with the same brush. It is necessary to remove carbon deposits so that some layers become light, others remain a little darkened, and still others are completely black.
Important! A distinctive feature of the method is the fact that as a result the board does not need additional tinting. Although, it might also be appropriate.
During chemical treatment, a concentrated alkali solution such as sodium hydroxide or potassium is applied to the surface. The board is left on for a long time, depending on the chemical and the type of wood used.
Then the alkali is washed off with water and a weak solution of acetic or citric acid, and subjected to the above-described grinding.
Preparation of alkali solution.
Tinting
Antique wood tinting with stain.
The tree darkens from time to time. Therefore, it is better to use pigments of dark shades for work. It can be interior oil, acrylic paint, stain or wax.
Applying oil to the treated board.
First, paint or oil is applied with a brush to the entire surface, quite abundantly. Then they take a cotton rag and erase the pigment from the protruding fragments of the relief, giving the surface an expressive texture.
Wipe the top layer with a rag.
Finally, the surface is covered with a transparent varnish for painting wood, which flows into the recesses and smoothes them. At this point, the work can be considered finished.
Output
Wooden products can be easily aged at home using simple tools. The video in this article demonstrates the entire process in detail.
rubankom.com
STROJABC.RU - Heat treatment of wood
As you know, wood is a beautiful, but capricious material. Fluctuations in temperature and humidity, fungi and mold - all this can seriously degrade the quality of wood. Therefore, it is customary to process wood before use, and until recently, processing was understood only as a chemical effect, which did not reflect in the best way on the environmental friendliness of the resulting wood. Since 2004, the EU has introduced a ban on the use of chemically treated wood. At the same time, technologies for thermal processing of wood, which are an alternative to chemical, began to be mastered.
To date, there are several methods of heat treatment of wood. They are all based on the use of very high temperatures, but otherwise they differ. So, the very first method of thermal action is based on the processing of wood in an air environment at a temperature of 200-240 ° C. Another technology involves the use of saturated steam to increase pressure and temperature to 185-212 ° C. There are also methods of thermal action on wood in nitrogen or oil environments.
What does wood heat treatment give? Under the influence of high temperatures, a number of wood parameters are improved:
- Heat-treated wood has increased water repellency, which prevents wood from rotting. Resistance to decay is also associated with the fact that at a processing temperature above 2000 C, chemical decomposition of hemicellulose and lignin occurs, which is simply impossible with conventional drying.
- As a result of a decrease in the moisture content of wood, its heat capacity sharply decreases (by 10–30%). As a result, heat-treated wood heats up very slowly, which is important, for example, for baths.
- Heat-treated wood is more stable. During operation, it tolerates changes in air humidity much better.
- The heat treatment process significantly increases the resistance of wood to biological damage (reproduction of fungi and microorganisms)
- The degree of deformation that occurs due to weather conditions in heat-treated wood timber is 20-90% less than that of untreated wood.
- Under the influence of high temperatures, the wood acquires magnificent shades. The most common types of wood for our latitudes, such as pine or birch, after heat treatment, in their appearance resemble exotic species.
Wood also has its drawbacks. Thus, an increased temperature reduces the elasticity of wood, as a result of which it becomes more fragile than ordinary wood. Therefore, for the device of supporting structures designed to withstand heavy loads, it is better not to use thermal wood.
Heat-treated wood - VikiStroy
In 1997, a new technology was introduced at one of the Finnish woodworking factories in Mikkeli, which was called<термообработка>... With this technological process, drying is carried out at a temperature of 150 - 230 degrees. The higher the temperature, the greater the weight loss due to the evaporation of volatile compounds (in other words, the wood becomes lighter). The greater the weight loss, the less water remains in the wood. Depending on the conditions of heat treatment and the type of wood, the residual moisture content of wood is 40 - 60% less than that of conventionally dried wood.
The heat treatment process usually takes about 24 hours. The moisture content of wood after heat treatment is reduced by 80 - 90%. As a result, its heat capacity significantly decreases: heat-treated wood heats up much weaker than untreated one, approaching in this indicator to abash. The surface of heat-treated wood is not porous, but dense, which significantly reduces the wood's ability to absorb moisture from the air (by 30% - 90% depending on the temperature and drying time).
In practice, this means that the tree is capable of repelling water without additional treatment with special impregnations. Heat treatment decomposes wood sugars, which are a breeding ground for microorganisms that contribute to wood decay. It becomes extremely resistant to decay, approaching in this indicator to larch, and, consequently, a hygienic material.
It should be especially noted that conifers almost completely lose resin, retaining a wonderful aroma that increases with increasing humidity and air temperature.
During heat treatment, the wood changes color, acquiring a beautiful brown tint. It should be noted that the color change is through, which is clearly visible on the cut. Scratches on such a surface are almost invisible. By varying the temperature of the heat treatment, it is possible to achieve the desired shade of wood and / or the degree of resistance to environmental conditions.
Where is heat-treated wood used?
Due to its beautiful appearance and the unique properties of heat-treated wood, it can be used in many areas, including for interior decoration of saunas, for external cladding of buildings, flooring, both parquet and board, for making garden furniture, boats, musical instruments, etc. NS.
From the point of view of planetary ecology, as a material for shelves in saunas and baths, heat-treated wood (including conifers) is a worthy alternative to the traditional abasha-sambo, which grows only in equatorial evergreens, the so-called<дождевых>forests - the main source of oxygen in the Earth's atmosphere, which cannot be restored. "
What happens to wood during heat treatment?
www.wikistroi.ru
for wood at home
Hello dear readers and subscribers of Andrey Noak's Blog! Do you know what is most important in wood materials? This is a quality drying. Each company uses a special drying technology. But if you wanted to dry the material yourself, then I will tell you how a vacuum dryer is made with your own hands. But first, a little theory.
Wood is a hygroscopic material, this is due to the fact that wood absorbs water vapor from the air. Each wood material has a different degree of moisture, depending on the storage conditions and the environment.
Why dry wood?
Drying is the process of removing moisture from a material by evaporation. When a tree grows, the metabolism in it is carried out by the circulation of moisture along the trunk. When cut, circulation stops and moisture begins to evaporate. In order to build a house or make any wooden product, you need to dry the logs with high quality.
Purchased vacuum dryer
A well-dried material is protected from fungi, damage and cracks, and the service life will be significantly increased.
If the drying was of high quality, then the product will serve you for many years.
Wood is divided into categories depending on the degree of moisture:
- wet is the one that was in the water and its moisture content is one hundred percent;
- freshly cut, with a moisture content ranging from 50 to 100%;
- air-dry, if the material has been exposed to air for a long time. The moisture content of such wood is about 15-20%;
- room-dry, with a humidity of 8-12%
- absolutely dry, the humidity of which is exactly 0.
Wet material will be difficult to process, but it is flexible and elastic.
Dry wood properties
Dry material has a higher biological resistance. After drying, the strength increases, better withstands the load. It is easy to process, and the products do not crack after processing, in contrast to the sour wood, in which the process of decay can even begin under suitable conditions.
Old ways of drying
A long time ago, people used only wood to build houses. Wooden dishes can be found in houses. Therefore, it was necessary to come up with ways of high-quality drying of logs, as the main building material. At that time, people used several drying methods.
Evaporation of wood
For this method, they took the necessary piece of wood, water and sawdust. The water was heated to 70 degrees, a workpiece was placed in it, then covered with sawdust and left for a certain time so that the material was steamed.
After drying, the workpiece did not crack, and the structure became denser and more flexible.
Waxing
Waxing is another method that has been widely used for a very long time. Here, wooden blanks were dipped into paraffin heated to 40 degrees and left for several hours. It was important to maintain the same temperature of the substance.
After the procedure, the wood should dry for several days. Material properties change after drying. The workpiece does not crack, does not rot and takes on an original tinted shade.
Craftsmen used this drying method to make wooden dishes, then skillfully painted the finished product.
Wood moisture, measurement methods
There are many ways to determine moisture content. To accurately determine the moisture content of wood, special devices are used. Electric moisture meters are able to determine humidity with an accuracy of 2-3%. The basic principle of such devices is based on the fact that wood of different moisture content has different electrical resistance.
There are many more "folk" methods for determining humidity, but they are used only by professionals:
- By weight, weighing the same pieces of wood of the same species in your hand or on a scale alternately.
- Experienced experts determine the moisture content "by eye", by the presence of cracks and faults.
- By shavings. When processing lumber, small chips are squeezed in a fist. If it wrinkles easily, then the material is wet. Dry wood is indicated by the brittleness of the shavings, but if the shavings crumble, then most likely the wood is overdried.
- Cutting. If, when processing wood with a chisel, a wet trace is noted, and the material is easily, smoothly cut, then it is not dried. It is better not to make a thread on such a surface, as cracks and flaws will appear when dry.
Putting together a vacuum dryer at home
It is very beneficial to dry the wood yourself, and if you do this with a vacuum dryer, the drying time will be reduced significantly. But buying a vacuum dryer in factories is expensive, and I will tell you how you can do it yourself, and also save money on it.
Drying at home takes place in special chambers. To equip it, you will need a large room, a heat source, and a fan to distribute heat inside the structure.
The floor, walls and ceiling of such a drying must be very strong, reinforced concrete or an iron conveyor is best. If you take a cheap second-hand iron conveyor, for example, from the railway, then it will even be a very cheap option. Or, for example, to reduce the cost, you can weld the conveyor yourself from old iron.
To preserve heat inside the chamber, we reinforce the walls with foam plastic and cover with clapboard. Instead of foam, you can use mineral wool or other insulation.
To reflect heat, you need to lay a special material. You can use foil, but penofol is also suitable, especially since its heat-reflecting and retaining qualities are much better.
We proceed to the installation of the heating device. The entire heating system must be installed separately from other heating circuits and must be constantly running. You can use a heating radiator, with which the water heats up to 65-90 degrees. In order for the heat in the chamber to be equally distributed, a fan is required, otherwise there will be uneven drying of raw materials and, accordingly, low quality. One more point, the temperature in the chamber should change smoothly and gradually.
When building your own drying facility, you must comply with all fire safety rules.
An important point is the construction of a system for loading lumber into the chamber. You will be immersing large and fairly heavy boards. For this, trolleys moving on rails or a forklift are well suited. The material is folded inside on shelves or just on the floor. To control the drying process, you must install special sensors, and these are thermocouples and vacuum (pressure) sensors. By doing everything right, you can get very high quality wood with a good presentation.
The main point in the construction of drying is to achieve the necessary parameters inside the chamber, and the materials and equipment that were used do not matter. In your chamber, you can reduce the drying process of raw materials to 2 weeks.
How vacuum drying works
After you have placed the material in the drying chamber and closed the door tightly, you can start drying. Air is extracted from the chamber to create a vacuum of about 9 - 10 bar. It is known that with a decrease in pressure, water boils faster.
Thanks to this technology, bound and free moisture will evenly move from the center to the periphery, thereby ensuring high-quality and uniform drying of the material, regardless of location.
Dry top wood cells will absorb moisture from those located in the core. First, thin areas dry out, then moisture from thicker layers moves to dry ones, thereby moisturizing them. If this process is interrupted, then the material may collapse, as the displacement of thinner layers begins.
Coating the ends of thick lumber to avoid quick release of moisture and crack formation during drying ...
To prevent displacement, lumber is treated with a special mixture, which is made from chalk, as well as drying oil. Often it is necessary to process the end parts of the workpieces.
Drying excludes the use of humidification systems, and no thermometers should be installed in the chambers. The process can be controlled using special sensors, which are controlled from the outside, often in a separate vestibule.
Very often vacuum installations are used for drying expensive species such as oak, merbau, paduk, wenge, zebrano. It is very convenient, since the wood is practically not destroyed during drying.
My help
I have the opportunity to provide advice on drying technology, selection of new and used equipment. You can contact me through SUPPORT.
Recently, my new book has been published, which gives recommendations for the operation of drying complexes in production. The information that is given in the book is simply unique, you will not find such information anywhere. More information about the book can be found in the section "MY BOOKS".
Good luck and see you soon!
Vacuum Dryer Video
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What is heat treatment of wood - features of the
Sections of the article:
Before the direct use of wood in construction, it must first be processed without fail. There are several methods for this. Otherwise, this material can swell under the influence of moisture, which will serve as an excellent breeding ground for fungi and various other bacteria.
Literally some time later, wood was treated only with chemical compounds. But because of the harmfulness of these funds, their use for such purposes has become prohibited.
What is wood heat treatment?
Thanks to thermal technologies, it is possible to process wood and abandon chemical compositions. After such processing, the properties of wooden elements improve, and, accordingly, the scope of their application expands.
You should know that at the moment the most effective way to heat wood is the technology of steam stabilization. Such processing is carried out within 12 hours.
During this treatment, the wood is exposed to steam at a temperature of 220 degrees. Thus, the structure of the wood changes. In this case, no chemical additives are used.
What are the qualities of thermowood?
Under the influence of such steam treatment, wooden elements improve their following qualities:
Moisture resistance. As a result, the ability to absorb water is reduced by about five times;
Stable value. When changes in humidity and temperature are observed, this indicator improves tenfold or more when comparing this wood with untreated wood;
Excellent resistance to biological damage. Due to the fact that wood is processed under the influence of high temperatures, polysaccharides are decomposed inside the material.
After all, they are the perfect breeding ground for bacteria and microorganisms. As a result, the operating period of wood is increased by almost 25 times.
Scope of Thermowood
Heat-treated wood is used in the manufacture of doors. Such structures do not deform during use. Although their price is almost the same as that of chipboard products. Yet their design and performance are top notch.
Steam-treated wood is also used in the production of Euro windows. Windows made of this material can easily withstand direct contact with moisture.
Parquet made from thermowood is much easier to install. There will be no ugly gaps between the elements, and the floor itself will last the maximum possible amount of time.
Do-it-yourself wood aging: types and methods of processing
Many design styles (French, Tuscan, vintage, shabby chic and others) are characterized by the presence of antique woodwork among their elements. Faded paint, texture of old wood give a special charm to the interiors. In their work, designers actively use antique furniture, wall panels, floors, stairs, beams, columns and other small decor. However, antiques are not cheap, which greatly inflates the cost of projects, and wooden elements from the past do not differ in strength and durability. To solve these problems, artificial aging of the tree appeared, and you can even do it yourself.
Aging methods
There are several ways to age a wooden surface. The choice of the required aging method is influenced by the type of wood, design style features, the availability of the necessary tools and materials, professional skills and experience. The following types of artificial aging of natural wood are most common:
- chemical method;
- heat treatment;
- brushing;
- aging of wood by dry brush method.
Chemical method
In order to process wooden products in this way, you must have special chemical reagents, professional tools, certain qualifications and knowledge. Corrosive substances (acids, alkalis or copper sulfate) are applied to the surface of the parts, after which the wood changes color, and the soft fibers are destroyed. The process itself is fraught with health risks and requires increased safety measures. It is almost impossible to implement such artificial aging with your own hands and at home.
Heat treatment method
The essence of this technological process consists in burning out less dense layers of wood by means of an open fire. It consists of several stages:
- annealing soft fibers to obtain the desired wood texture;
- cleaning the surface with abrasive materials;
- applying varnish.
To implement this method with your own hands, you can use a completely affordable tool - an ordinary blowtorch.
Brushing
The name of this technique comes from the English word "brush", which means brush. Brushing is based on the features of the structure of wood, consisting of hard and soft fibers, and the process itself consists in combing out soft fibers from the wood with a metal brush and giving the surface the texture of old wood. DIY brushing can be broken down into a number of sequential stages:
- mechanical processing of wood along the grain;
- cleaning from shavings and lint;
- glossing;
- staining or patina;
- varnishing.
Despite the fact that the brushing tool seems extremely simple, the process itself is quite laborious. When using this method of applying a touch of antiquity to wooden products, it should be remembered that hardwoods, as well as pine, yew and larch, do not lend themselves to brushing.
Artificial aging of wood using a dry brush method
This process is also easy to do with your own hands, it is applicable to cabinets, tables, whatnots, armchairs and other types of home furniture. It consists of several stages, and not all of them are required.
- Creation of the effect of many years of operation.
At this stage, scratches, gouges, chips and dents are applied to the surface of the furniture. To do this, you need a carpentry tool and a little imagination. Since the damage caused is irreversible, this stage of tree aging can be skipped.
- Coloring.
For this, two paint options of similar shades are used. First, one is applied, and after drying - the second.
- Surface treatment with abrasive materials or sanding.
The top layer of paint is erased with fine sandpaper or sand. This is done unevenly, in places only to the first layer, and in places to wood. It is important to achieve a natural scuff effect, therefore special attention should be paid to edges and protrusions. After sanding with a vacuum cleaner, shavings and wood dust are removed.
- Application of paint with a dry brush.
It is important to find the right paint application tool at this stage. A stiff, flat brush works best. The choice of paint should also be approached responsibly. It should be in contrast to previously used shades. For a light base, the best option would be dark shades of brown or burgundy paint. The technology of applying paint to the surface in this method of aging wood is the most complicated. Apply the paint with your own hands with an almost dry brush, the strokes should look like a trace of numerous bristles. Intersection of strokes is not allowed.
- Rubbing the top layer.
For this, a cloth napkin is used, which is used to lubricate the newly applied strokes.
- Surface coating with varnish.
It is best to use clear varnish, which should be applied in one or two coats.
There are several more methods for forced aging of wood with your own hands, but they are not as effective and do not always achieve the desired goal.