Natural moisture content of wood. Determination of moisture content and drying of wood

Determination of moisture content and drying of wood

1. DETERMINATION OF WOOD HUMIDITY.

There are several ways to determine wood moisture content. To determine humidity, you can use a special device - an electric moisture meter. The operation of the device is based on changes in the electrical conductivity of wood depending on its humidity. Electric moisture meter needles with electrical wires connected to them are inserted into the wood and passed through them electricity, while the moisture content of the wood is immediately marked on the instrument scale in the place where the needles are inserted. Electric moisture meters EVA-2M are widely used, determining humidity in the range of 7 - 60%.
Many experienced carpenters determine the moisture content of wood by eye. Knowing the types of wood, its density and others physical properties, you can determine the moisture content of wood by weight (weighing several identical pieces of the same species in turn), by the presence of cracks at the end or along the wood fibers, by warping and other signs.
With the weight method, a section of moisture 10-12 mm thick is sawed off from a board (control sample) at a distance of 300 - 500 mm from the end, thoroughly cleaned of burrs and sawdust and weighed, the result is recorded in a journal, and the section is placed in a drying cabinet with a temperature of up to 103 °C. After 6 hours of drying, the section is weighed and the mass is recorded in a journal, then dried again and weighed every 2 hours after drying. If after repeated weighings the mass of the section does not change, this means that the section is dried to an absolutely dry state with humidity W0 = 0% and mass P.

The initial moisture content of the sample wood is determined by the formula:

W = (P n - P s) : P s * 100%,

where W is the initial humidity, %;

Р n and Р с - initial mass and mass in an absolutely dry state of the sample.

Also, checking the current humidity during the drying process can be carried out by weighing control samples with a length of at least 1000 mm, which are also cut from the boards to be dried at a distance of 300 - 500 mm from the end, cleaned of bark, burrs, sawdust, after which the ends are painted. . The sample is weighed to the nearest 5 g.
When processing lumber with a plane, its thin shavings, compressed by hand, are easily crushed, which means the material is wet. If the chips break and crumble, this indicates that the material is dry enough. When making transverse cuts with sharp chisels, also pay attention to the shavings. If they crumble or the wood of the workpiece itself crumbles, this means that the material is too dry.
The complete saturation of wood with water is called the hygroscopic limit. This stage of humidity, depending on the type of wood, is 25-35%.
In practice, wood is distinguished: room-dry (with a humidity of 8-12%), air-dry artificially dried (12-18%), atmospheric-dry wood (18-23%) and damp (humidity exceeds 23%).
Wood from a tree that has just been cut down or has been for a long time in water is called wet, its humidity is up to 200%. There is also a distinction between operational humidity, which corresponds to the equilibrium moisture content of wood under specific conditions.

Requirements for wood moisture content in products

Table 1.

The moisture content of freshly cut wood (which has the moisture content of a growing tree) depends on the species and the location of sampling along the cross section of the trunk. U coniferous species The moisture content of the wood in the peripheral part of the trunk (sapwood) is greater than the moisture content of the wood in the central part of the trunk (core). In deciduous trees, the moisture content throughout the entire section of the trunk is approximately the same.
The moisture content of driftwood is usually higher than that of wood delivered overland, and the moisture content of driftwood is higher than that of freshly cut wood. Thus, the moisture content of the sapwood part of pine logs after rafting increases to 150%, and the core part of the logs - to 50%.
As you know, wood has a cellular structure. Moisture in wood can fill cell cavities, intercellular spaces and permeate cell walls. Moisture that fills cell cavities and intercellular space is called free, and permeating the cell walls - related, or hygroscopic.
Freshly cut wood has both free and bound moisture. When drying wood, first remove free moisture, and then connected.

Moisture content of freshly cut wood

Table 2

2.DRYING WOOD.

When making any type of joinery, the wood must be dry. Dry wood has high strength, less warped, not susceptible to rotting, easy to glue, better finishing, more durable, finished products do not crack. Any wood of various species reacts very sensitively to changes in environmental humidity. This property is one of the disadvantages of timber. At high humidity, wood easily absorbs water and swells, but in heated rooms it dries out and warps. Therefore, for joinery products, wood must be dried to the degree of humidity that is expected in the future during their use. In the room, the wood humidity is sufficient up to 10%, and under open air- no more than 18%.
Drying is the process of removing moisture from wood by evaporation. Drying of lumber can be natural or artificial.

NATURAL DRYING

Natural drying occurs under the influence of atmospheric circulating air, which evaporates moisture from the wood. Natural drying of lumber is combined with storage. It is necessary to dry the wood in the shade, under a canopy and in a draft. When dried in the sun, the outer surface of the wood quickly heats up, but the inner surface remains damp. Due to the difference in stress, cracks form and the wood quickly warps. Wet lumber is dried immediately after sawing. This prevents the appearance of wormholes and rot.
Stacked materials dry worse in spring than in summer. This process occurs more intensively in June. Drying time for softwood lumber natural conditions up to 18 - 22% humidity is given in the table.
Time required to dry lumber stacked with spacers to 18-22% moisture content:

Table3

Note: For larch, drying time increases by 60%.

Climate zones

1st - Arkhangelsk, Murmansk, Vologda, Kuibyshev, Perm, Sverdlovsk, Sakhalin, Kamchatka, Magadan regions, the northern half of Western and Eastern Siberia and Komi, the northern part of the Khabarovsk Territory and East End Primorsky Krai.

2nd - Karelia, Leningrad, Novgorod, Pskov regions, the southern part of the Khabarovsk Territory and the western part of the Primorsky Territory.

3rd - Smolensk, Kaliningrad, Moscow, Tver, Orel, Tula, Ryazan, Ivanovo, Yaroslavl, Nizhny Novgorod, Bryansk, Chelyabinsk, Vladimir, Kaluga, Kostroma, Amur regions, the southern part of Western and Eastern Siberia, the Republic of Chuvashia, Mari El, Mordovia, Tatarstan, Bashkotorstan, Udmurtia.

4th - Kursk, Astrakhan, Samara, Saratov, Volgograd, Orenburg, Voronezh, Penza, Tambov, Rostov, Ulyanovsk regions, North Caucasus.

Natural drying of lumber decreases sharply from mid-August. Spruce lumber dries faster than pine lumber. Thin-size materials dry faster than thick-size materials. Sawn softwood 16 mm thick loses half of the initial moisture content after 4 days of drying, then the drying intensity drops sharply. Lumber with a thickness of more than 20 mm most moisture evaporates after 20 - 30 days of drying.
Laying the stack begins with the construction of the base, the height together with the logs is at least 50 cm. The top of the base must be horizontal. The base supports are placed in increments of 1.5 m to prevent deflection of the lumber. The shape of the stacks is square or rectangle.
Stacks of lumber are protected by a roof that protects the material from precipitation and direct exposure sun rays and dust.
The lumber is laid on dry softwood pads measuring 25x40 mm. The outermost spacers are laid flush with the ends of the boards, and the rest at a distance between them of no more than 70 cm. To create better ventilation of the stack, all spacers are laid in a strictly vertical row along a plumb line. Between the boards or bars stacked in stacks, equal-width gaps (splits) are left, forming vertical channels along the entire height of the stack. The width of the spacing, depending on climatic conditions and the cross-section of the boards, is set for lumber with a thickness of up to 45 mm from 1/2 to 3/4 of the width of the lumber and for lumber with a thickness over 45 mm from 1/5 to 1/3 of the width of the lumber. To ensure uniform drying of lumber along the height of the stack, vents 150 mm high are installed at a distance of 1 and 2 m from the bottom row of boards. The boards are laid with the inner faces up to reduce their warping. To prevent cracking, it is recommended to carefully paint the ends of the boards oil paint or soak several times in hot drying oil to protect the pores of the wood. The ends should be processed immediately after cross-cutting to size. If the tree is different high humidity, then the end is dried blowtorch, and only then paint over it.

ROOM DRYING OF TIMBER

Chamber drying is the main method in which lumber is dried in drying chambers having the necessary equipment and devices. The chambers regulate temperature, humidity and the degree of air circulation.
Atmospheric drying is used for preliminary drying of lumber and, as a rule, is combined with a wood drying chamber.
Lumber can be stacked in pieces or in batches. When forming a stack individually, dry (with a moisture content of no more than 18%) calibrated softwood and hardwood pads with a cross-section of 25 x 40 mm and a length equal to the width of the stack are laid between the rows of boards. Spacers along the height of the stack must be laid perpendicular to the boards and strictly vertically one above the other.
The stack is formed from boards of the same type and thickness. The number of spacers laid along the length of the stack is given in the table:

Number of spacers laid along the length of the stack

Table4

Note: The numerator is the number of spacers for stacks made of softwood, the denominator is the number of spacers made of hardwood.

Methods for stacking lumber depend on the direction (circulation) of the drying agent. For drying chambers with countercurrent circulation, lumber is laid at intervals (splits), and for chambers with transverse reverse and countercurrent rectilinear circulation - densely.

Drying modes

Drying of lumber occurs under a certain temperature and humidity regime, which is understood as a natural alternation of processes of temperature and humidity effects on wood in accordance with its humidity and drying time.
During the drying process in the chamber, the air temperature gradually increases (in stages) and the relative humidity of the drying agent decreases. Drying modes are prescribed taking into account the type of wood, the thickness of the lumber, the final moisture content, the quality category of the materials being dried and the design (type) of the chambers.

Depending on the requirements for lumber, modes are divided into:

· soft M, with soft modes defect-free drying is obtained with preservation physical and mechanical properties wood and color;

· normal H, under normal conditions defect-free drying is obtained with a possible slight change in color coniferous wood, but maintaining strength;

· forced F, with forced drying modes, wood is obtained with preservation of bending, tensile and compressive strength, but with a decrease in chipping and splitting strength by 15 - 20% and with possible darkening of the wood. These modes provide for a three-stage change in the parameters of the drying agent, and the transition from each stage of the mode to the next can be made only when the material reaches a certain humidity specified in the mode.

High-temperature drying process modes for batch kilns
provide for a two-stage change in the parameters of the drying agent, and the transition from the first stage to the second is made when the wood reaches a moisture content (transition) of 20%. The high temperature regime is determined depending on the species and thickness of the lumber.
High-temperature conditions can be used for drying wood used for the manufacture of non-load-bearing elements building structures, in which a decrease in strength and darkening of wood is allowed.

Wood drying process

Before the drying process is carried out according to the selected mode, the wood is heated with steam supplied through humidifying pipes, with heating devices turned on, fans running and the sugar-exhaust ducts closed. At the beginning of heating, the temperature of the drying agent should be 5°C higher than the first stage of the mode, but not more than 100°C. The degree of saturation of the environment should be for wood with an initial moisture content of more than 25% in the range of 0.98 - 1, and for wood with a moisture content of less than 25% - 0.9 - 0.92.
The duration of the initial heating of wood depends on the type of wood and for lumber of coniferous species (pine, spruce, fir and cedar) at an outside temperature of more than 0°C is 1 - 1.5 hours at a temperature below 0°C - 1.5 - 2 hours for every centimeter of thickness. The duration of heating of lumber of soft deciduous species (aspen, birch, linden, poplar and alder) increases by 25%, and for lumber of hard deciduous species (maple, oak, ash, hornbeam, beech) increases by 50% compared to the duration of heating of coniferous wood breeds
After warming up, the parameters of the drying agent are adjusted to the first stage of the mode and then they begin to dry the lumber, observing the established mode. The temperature and humidity of the air are regulated by valves on the steam lines and gates of the sugar-exhaust channels.
During the drying process, residual residues appear in the wood. internal stresses, to eliminate them, intermediate and final moisture-heat treatment is carried out in an environment of high temperature and humidity. In this case, lumber is processed, dried to operational humidity and subject to further mechanical processing.
Intermediate moisture-heat treatment is carried out during the transition from the second to the third stage or from the first to the second when drying at high temperatures. Lumber of coniferous species with a thickness of 60 mm and above and deciduous trees (depending on the species) with a thickness of 30 mm and above are subjected to moisture-heat treatment. In the process of heat and moisture treatment, the temperature of the environment should be 8°C higher than the temperature of the second stage, but not more than 100°C, with a degree of saturation of 0.95 - 0.97.
The final moisture-heat treatment is carried out only when the wood reaches the required final average moisture content. During the final heat and moisture treatment, the temperature of the environment is maintained 8°C above the last stage of the regime, but not more than 100°C. At the end of the final moisture-heat treatment, the dried lumber is kept in the chambers for 2 - 3 hours at the parameters provided for by the last stage of the regime, after which the chambers are stopped.

Wood is natural material, which is very susceptible to changes in humidity levels and temperature regime. The main property of wood is its hygroscopicity, that is, the ability to change the level of humidity according to environmental conditions. This process is called “breathing” of wood, in which it can absorb air vapor (sorption) or release it (desorption). Such actions are a response to changes in the microclimate of the building. If the state of the environment does not change, then the moisture content of the wood will tend to a constant value, which is called equilibrium (or stable) moisture content.

How to determine the moisture content of lumber

In order to calculate the moisture content of timber, there are several methods:

Several varieties of the concept of “humidity”

Humidity is one of the main characteristics of wood. Humidity is the percentage ratio of the amount of liquid to the dry mass of wood. Liquid in wood is present in a bound (hygroscopic) and free state. From these values ​​the total amount of moisture in the wood is calculated. Bound moisture is located in the walls of woody cells, and free moisture fills the cavities in and between the cells. Free water is easier to remove than bound water and has less impact on the properties of timber. The moisture content of dry lumber should be from 8 to 16%.

There are several concepts of “humidity”:

• initial moisture content is the amount of moisture in the wood before it is sent to dry. Freshly cut wood has a maximum moisture level that is different varieties tree can be above 100%. For example, balsa wood has a moisture content of about 600% when freshly cut. Most often, the types of wood that are more familiar to us have an initial or natural moisture level ranging from 30 to 70%
• final moisture content is the level of moisture that must be obtained by drying
• Transport moisture content of lumber is at the level of 20 -22%. In order to transport timber with natural moisture content, it must first be dried. Atmospheric drying of lumber is carried out in accordance with GOST. The drying process significantly increases the protective properties of timber and also stabilizes their physical and mechanical parameters
• operational humidity is the humidity coefficient at which wooden products are operated.

What should be the natural moisture content of lumber? GOST 3808.1-80 regulates this indicator at 22%. Natural moisture content timber can be created from almost any type of wood. In the territory Russian Federation such raw materials are produced mainly from wood coniferous varieties such as spruce, pine, cedar or larch.

Planed boards and timber made from such varieties are distinguished by an increased level of strength and resistance to the effects of the environment on them, for this reason they are perfect for internal and external works in a buiding. This material is produced by simply sawing logs.

Do not forget that lumber with natural moisture can rot and be damaged by microorganisms, so they must be subjected to protective treatment.

The timber is produced in a variety of sections, which makes it possible to purchase exactly the option that the best way suitable for solving the assigned tasks. The main advantages of natural moisture timber include high quality and affordable cost. Compared with the cost of dry timber, the price of wet material is almost 30% lower.

Operating humidity values ​​for lumber and wooden products

What is drying? Drying lumber is one of the most important and integral operations in technological processes woodworking, and largely determining the quality and competitiveness of finished products. Wood containing a large number of water, is easily affected by fungi, as a result of which it rots. Dry wood is more durable. A decrease in humidity leads to a decrease in wood mass and an increase in its strength. Dry wood, unlike raw wood, is easy to trim, process and glue. It does not change its size and shape, which is important during the manufacturing and operation of products.

As a result of drying, wood is transformed from natural raw material into industrial material, meeting a wide variety of requirements that are placed on it in different industrial and domestic conditions. MUCH MORE EXPENSIVE THAN RAW! They include the cost of drying, which is quite high, but all this is paid off by the quality of the product and its demand on the market.

Wood moisture content is the ratio of the mass of water to the mass of dry wood, expressed as a percentage, and is used to estimate the amount of water contained in wood.

After cutting down a tree and sawing it into boards, the wood tissue turns out to be more or less porous, depending on the type of wood, and more or less saturated with lymph - water, which precisely represents what in technical jargon is called “wood moisture”.

A freshly felled tree has a maximum moisture content, which for different species can even exceed 100%. Usually they deal with a lower humidity value (30 - 70%), since after cutting some time passes before sawing and placing it in the dryer, and it loses a certain amount of water.

The initial moisture content is taken to be the value that the wood has before being sent to dry.

The final humidity is the humidity we want to achieve.

Humidity of 20-22% is called transport, and the humidity at which the product is operated is called operational.

Operating humidity values ​​for lumber and wooden products:

Table of operational humidity of lumber

So how do you get dry wood? How is it dried?

Drying lumber and drying chambers.

Drying wood is a long and energy-intensive process. Thermal energy for dryers is produced in boiler houses. The heat carrier here is steam or hot water. Environmental parameters in drying chambers are usually measured with a psychometer. Management and regulation is carried out automatically. These are dryers classic type: convective with various systems supply and exhaust ventilation and types of coolant. Their advantages: low capital costs, simplicity of the process, ease of maintenance, high quality of drying.

Along with traditional convection chambers, vacuum, condensation, microwave and other dryers have become widespread, but their use does not always achieve the desired result.

IN Lately There have been significant changes in the organization, technique and technology of drying. If previously the main volume of drying was accounted for large enterprises Where large drying shops were built, now the bulk of the wood is processed in small enterprises, the needs of which can be met by one or two small-capacity chambers. Many small firms are trying to create homemade simple drying devices that cannot provide high-quality drying of the material. At the same time, The market is placing increasingly stringent demands on the quality of wood products.

Low drying quality due to unsatisfactory technical condition dryers and poor technological training of personnel, leads to hidden defects - uneven distribution of final moisture, which can go unnoticed for a long time and affect when the product is already in operation.

Modern convective forest drying chambers, both domestic and foreign, make it possible to achieve High Quality drying. They are equipped with a system automatic control process and are a complex set of equipment requiring qualified maintenance.

Now that we have cleared up the questions regarding what exactly is dry lumber, You can safely begin to review the market, draw up an estimate for construction or repairs, and will no longer become a victim unscrupulous sellers lumber.

Wood is a very hygroscopic material that easily changes its humidity. The moisture content of wood is the percentage of water (moisture) in it. The moisture content of wood does not depend on the type of wood. Wood moisture content is a quantitative indicator of the moisture content in it

Wood moisture content

Moisture exchange occurs all the time between wood and air. Therefore, the moisture content of wood is a very unstable value, which changes along with the humidity of the environment. If the humidity of the wood is greater than the humidity of the surrounding air, the wood will dry out. If it's the other way around, it's hydration. And if the humidity and temperature of the environment (air) remain constant for a long time, then the humidity of the firewood will also stabilize and will correspond to the humidity of the surrounding air.

Humidity of wood at which the exchange of moisture between it and environment, called “equilibrium”

In nature, equilibrium moisture content for wood is an extremely unstable state. Because in nature it is impossible to find air with constant temperature and humidity parameters for a long enough time. However, the state of equilibrium humidity is easily achieved for wood located in an artificial microclimate, for example, in a drying chamber or simply in any other room with constant temperature and humidity.

Distinguish between absolute and relative humidity of wood

Absolute humidity of wood

Absolute humidity is the ratio of the mass of moisture contained in a wood sample to the mass of absolutely dry wood of the same sample. According to , the value of absolute humidity (W) is calculated after examining (drying) the sample, according to the formula:

W = (m - m 0) / m 0 x 100,

where (m) and (m 0) are the mass of the sample before and after drying.

The concept of the value “absolute humidity”, according to GOST 17231-78, is interpreted simply as “humidity”. Like everything “absolute”, the value of “absolute humidity” is divorced from real world and is an extremely indigestible form for thermotechnical calculations. For example, at an absolute humidity of 25%, a kilogram of wood will contain 200 grams of water. This discrepancy in numbers confuses calculations.

The relative humidity value is more convenient and practical

Relative humidity of wood

Relative (working) humidity of wood is the ratio of the mass of moisture that a wood sample contains to its total mass. According to GOST 17231-78, the value of relative humidity (W rel.) is calculated from the value of absolute humidity (W) of the sample, according to the formula:

W rel. = 100W / (100+W)

or more simply,

W rel. = m water / m sample x 100

Relative humidity is a very simple and convenient form for taking into account evaporated water in wood-burning heat engineering calculations. The value of relative humidity directly indicates the quantitative water content in wood. For example, one kilogram of wood with a moisture content of 20% will contain 200 grams of water and 800 grams of dry wood matter.

For comparison, let’s put a “live” example into a table. This is a table for the same our sample. Let us determine and compare the values ​​of its absolute and relative humidity:

Wood moisture level

According to humidity, all wood is divided into three groups: wet (humidity more than 35%), semi-dry (humidity from 25 to 35%) and dry (humidity less than 25%). Initially, the humidity of freshly cut trees is 50-60%. Then, during natural drying under a canopy in the air, the wood loses up to 20-30% of its moisture over the course of one and a half to two years and reaches a condition of relative humidity. After this, the moisture content of the wood no longer changes significantly, and its value is ≈25%. Such wood is called air-dry. To reduce the moisture content of wood to a room-dry state (7...18%), it must be dried forcibly in drying chambers, or moved to long time into an artificial microclimate with specified conditions (for example, move it to a room or other premises).

There are the following degrees of wood moisture content:

• Splavnaya(humidity 60% or more)
  This could be a tree that has been in water for a long time. For example, driftwood, or wood after sorting in a water basin, or simply a well-wetted (damp) log.
• Freshly cut(humidity 45...50%)
  This is wood that has retained the moisture of a growing tree.
• Air dry(humidity 20...30%)
  This is wood that has been aged for a long time outdoors, with good ventilation.
• Room dry(humidity 7...18%)
  This is wood that has been in a living room or in another heated and ventilated room for a long time.
• Absolutely dry(humidity 0%)
  This is wood dried at a temperature of t=103±2°C to constant weight.

Calorific value of wet wood

The calorific value of wood is directly dependent on its moisture content. The moisture content of firewood is a determining indicator of its quality. That dry wood burns better than wet wood is known to many, if not everyone. And everyone knows that wet firewood can always be dried, and dry firewood, on the contrary, can be wetted. Accordingly, the quality of the fuel will change - improve or deteriorate. But is this really important for modern heating equipment? For example, wood-burning pyrolysis boilers allow you to burn wood with a humidity of up to 50%, and even up to 70%!

The table shows generalized indicators of the calorific value of wood for each degree of its moisture content.

The table shows that the lower the moisture content of the wood, the higher its calorific value. For example, air-dried wood has a working calorific value almost twice as high as freshly cut wood, not to mention wet wood.

Wood with a humidity of 70% or higher practically does not burn.
Perfect option For wood heating- this is to use firewood in a state of room-dry humidity. They provide such firewood maximum amount heat. But, since drying firewood to such a state is associated with additional energy costs, the most the best option For heating, air-dried wood will be used. Bringing firewood to an air-dry state is relatively easy. To do this, it is enough to prepare them for future use and store them in a dry, ventilated area.
Finally, I would like to note that the moisture contained in firewood not only worsens its calorific value. Increased moisture content in fuel negatively affects the combustion process itself. Excess water vapor serves as the basis for creating an aggressive environment, which causes premature wear of the heating unit and chimneys.
Manufacturers of modern heating equipment recommend using air-dry wood as fuel, with a humidity of no more than 30-35%

Wood is one of those materials that are sensitive to changes in external environment, primarily to fluctuations in temperature and humidity. One of the key properties of wood is the ability to absorb atmospheric moisture, i.e. hygroscopicity.

What is the natural moisture content of wood?

Under natural humidity wood refers to the moisture content that is present in the still growing state of the tree or after it has been cut down and sawed into individual elements without any additional drying. This figure varies very widely - on average from 30% to 80%, specific figures depend on specific type wood

Coniferous species are characterized by the highest natural humidity:

• Spruce - 90%;
• Different types of pine trees - 88-92%;
• Fir - 90-92%;
• Larch - 80-82%

Soft hardwoods:

• Willow - 85%;
• Aspen, alder - 80-82%;
• Linden - on average 60%.

Hardwoods:

• Different varieties of birch trees - 68-78%;
• Beech - 65%;
• Elm - 75-78%;
• Hornbeam - 60%;
• Oak - 50%.

At the same time, wood felled in winter period has a lower level of humidity than summer.

How and why is wood dried?

After sawing into individual boards/beams, the wood is dried under atmospheric conditions or using chambers, hydrophobic liquids, and various heating elements.

Drying wood protects or at least reduces the likelihood of its rotting, prevents deformation of shape and size, and improves the quality of finishing finished product, increases the strength of adhesive joints. During the drying process, not only weight loss occurs wooden element due to water loss, but also a slight change in size - up to 5-7% in length, width or height.

The main purpose of drying is to bring the wood to the so-called. equilibrium humidity, i.e. one that it would acquire after a certain period of operation under specific conditions. If this is not done artificially, then the process will occur naturally - for example, doors will begin to become damp and swell, parquet or lining may dry out, and as a result, cracks will appear at the joints of individual elements, etc.

Depending on where and under what conditions a product made from this wood is subsequently used, it is dried to a certain level of humidity. So for floor coverings optimal humidity will be 6-8%, for those items that will come into contact with atmospheric air(those. window frames, doors) - 11-12% or even more in the case of a humid climate in the region.