The wood must be dried before use. A moisture meter is used to measure the humidity outside and inside the workpiece. Most hygrometer models determine the moisture level in a log or log house with high accuracy. This is carried out at timber processing enterprises and in lumber production shops.

Operating principle of the device

Before the advent of electronic moisture meters, the humidity level was determined according to GOST. This is a long and labor-intensive process, which gave accurate indicators only with strict adherence to research algorithms. The disadvantage of the method is that it is difficult to obtain the value.

Moisture meters are designed to almost instantly determine the moisture content of a material.. The operating principle of the devices is based on measuring specific electrical resistance tree. This parameter changes depending on the amount of water in the structure of the material, to which the device reacts. The meters calculate the degree of humidity with an error of 0.5 to 4% based on several parameters:

Local measurements. In one trunk different areas the level of moisture saturation is different. To reduce inaccuracy, measurements are taken in several places on the workpiece.

Rocks have different densities. Coniferous and deciduous trees have different characteristics. For example, by density. Many moisture meters whose software includes a rock identification function can take this feature into account.

The undoubted advantage of using a device for measuring humidity over the GOST method is maintaining the integrity of the product.

Main types

Operating principle of a moisture meter - analysis resistivity material for the passage of current, but the accuracy depends on the characteristics of the device. The device must be selected based on the purpose of its use and the scale of production.

Conductometric needle moisture meter

The device for determining humidity by contact method is equipped with probes that need to be inserted into the wood. In her body, the device creates an electrical impulse between the electrodes and determines the size of the resistance of the medium. The value is displayed on the screen.

Advantages of the devices:

• low price;
• high reliability of the result with correct insertion of needles into the mass;
• ease of use.

Flaws:

• the material has to be damaged, and this is undesirable when measuring hard and expensive rocks, finished products;
• The electric moisture meter is unable to reliably measure humidity below 4%. This drawback is insignificant; less than 5% is the normal level of water content in the finished product.

The device rarely becomes unusable; for adjustment, sometimes it is necessary to replace the crown, which you can do yourself.

Non-contact electric moisture meter (dielcometric)

The moisture meter has a built-in radio frequency generator. It scans building materials from a distance without the need to penetrate into the mass.

Advantages of the device:

• an electric moisture meter can determine humidity with low error;
• suitable for analyzing the quality of raw materials and finished wooden products;
• many models include a value memory function;
• does not require damage to the wood.

Flaws:

• high cost of the device;
• Repairing a moisture meter will not be cheap; a specialist is required.

How to use a moisture meter: turn on the device, apply the contact surface to the material or move it to the distance specified in the instructions. For devices, the working element can be located on the back side of the device or as an external measuring cylinder (see photographs of non-contact devices).

Hygrometer overview

Psychrometers for measuring the amount of moisture in wood are used when studying the material in laboratories, in woodworking shops and in the production of products. Large companies who are conscientious about their business, carry out quality control of raw materials at all production stages. To do this, they use devices with certain characteristics from different brands.

Needle meters

• The EV 2K electric moisture meter (see photo) meets the requirements of GOST 22261-76 and GOST 24447-80. This is an industrial moisture meter designed to work with all types of lumber from different breeds tree. The old-style conductometric model works using the contact method. Allows you to determine humidity at air temperatures of +5–400 ˚C. The average price of the device is 2000 rubles.

• Moisture meter KWB 0121-00 is a modern Chinese conductometric device. It is capable of measuring and analyzing the condition of wood, concrete and some others building materials. Its disadvantage is low level penetration into the material, resulting in a high degree of error. Function automatic shutdown during inactivity, extends battery life. Average price – 2000 rub.

• Gann needle wood moisture meters (Germany) are used in wood drying and storage shops. Various models measurements are taken at a depth of 5 to 40 mm in the range from 5 to 50%. The choice of model is made based on the production needs of the enterprise. Price from 120 to 440 euros.

Non-contact devices

• Moisture meter for building materials VSM-1 – universal tool to determine the level of water saturation in wood, stone, concrete during construction and during repair work. You can enter 25 graduated dependencies into the device, which will reduce the error in the result. The device is widely used in laboratory research. The average price of the device is high - about 35,000 rubles.

• The hydrocondtroleasy non-contact moisture meter is a domestically assembled device. Designed for quick measurement of moisture in lumber in accordance with GOST 16588. The device determines the amount of moisture inside large logs and beams along the entire length. Works with 7 groups of wood species. Given its versatility of use, an electric moisture meter is relatively inexpensive - from 5,800 rubles.

• Merlin instruments (Austria) are designed for measuring moisture in wood of different thicknesses: logs, boards, parquet, with planed and untreated surfaces. The choice of model should be made based on the thickness of the products being tested. The merlin HM8-WS25 meter can be called universal: the depth of the surface under study is up to 40 mm, the analysis spectrum is from 4 to 99%. Comfortable touch screen and a clear interface make using the device accessible to any controller. The cost of the moisture meter is 37,000 rubles.

• The micro hydro control device measures the moisture content of shallow layers, used in furniture production, finishing materials made of wood, parquet, solid doors. The device is capable of analyzing 23 types of wood. The compact dimensions of the moisture meter (see photo) and low price (about 3,000 rubles) are its main advantages.

• The MG4U wood moisture meter is a universal device for determining the condition of bulk and solid building materials. This is a moisture meter for sawdust, crushed stone and other bulk materials, as well as solid products. The software complies with GOST 21718 and GOST 16588. The device is included in the State Register. Price – about 43,000 rub.

• The MG4B device is equipped with 13 calibration curves for solid stone materials different densities and 15 algorithms for wood. The characteristics are similar to MG4U, adapted for working with hard materials. Price 32,000 rub.

• ADA ZFM brand meters are designed for hard and soft wood, drywall, brickwork. Work surface located on the back of the device. Measuring range – 0–100% humidity, measurement accuracy ±4%. The cost of the product is 2200 rubles.

For ease of selection

To easily select a moisture meter, we summarize the presented models in a table with the main technical indicators.

Moisture meters differ in the main parameters: accuracy of determination, identification of different tree species, depth of transmission of measuring pulses. It is these characteristics that must be relied upon when choosing a device. The size of the error also matters: for the production of critical products it is necessary to obtain accurate and reliable data. On the other hand, in production, the device is useful for measuring the moisture content of the raw material trunk, and the condition of the finished board after drying. In all cases, different characteristics of the moisture meter are required.

Table data may differ from actual data, the information is for informational purposes only. Sellers will provide more accurate specifications.

Determining wood moisture content

To determine the moisture content of wood, you can use one of two methods. In everyday life, special devices are used - electric moisture meters. The device works on the principle of changing the electrical conductivity of wood (changes with humidity). The needles of an electric moisture meter, with connected wires, are inserted into the wood and an electric current is passed through it; at this moment, on the scale of the device you can see the degree of moisture in the wood in the place where the measurement is being taken.

Some carvers with great experience works can determine the moisture content of wood by eye. Also, knowing the density and other physical properties different types wood - you can determine its moisture content by mass, if there are cracks along the fibers or at the end - by warping. By the color of the wood, the color of the bark and its size, freshly cut or ripe wood is determined, as well as its moisture content.

If, when processing wood with a plane, the chips are easily compressed by hand, the material is wet, but if, when compressed, the chips crumble and break, the material is quite dry. You also need to pay attention when making transverse cuts with chisels: if it crumbles wooden blank– the material is too dry.

A piece of wood, which is very easy to cut, is very wet, and a wet mark will be noticeable at the cut site. Note that to get high-quality wood preparation quite difficult, since warping, cracking and other deformations during drying cannot be avoided.

Drying wood

Dry wood is stronger, more durable, better finished, easily glued, does not rot, and does not warp so much. Any wood, regardless of its species, subtly senses changes in the humidity of its environment. This property is one of the most important disadvantages of timber. In warm and heated rooms it warps and dries out, and at high humidity it very quickly absorbs water and begins to swell. Optimal humidity wood outdoors is 18%, and indoors – up to 10%.

Today there are many different methods for drying wood. The most accessible and simplest is natural look drying – air (atmospheric). Drying should take place in the shade, in a draft and under a canopy. When drying in the sun, the surface quickly heats up and dries, but the inside of the workpiece remains damp. As a result, cracks appear (due to stress differences).

Beams, boards and other p/m must be stacked on wooden, metal or other supports with a height of 50 cm. Boards must be laid with the inner faces towards the top to avoid warping.

If the boards are placed on the edges when drying, the process will be faster, since there will be better ventilation and, accordingly, the moisture will evaporate faster. However, there is a significant drawback - the boards warp more, especially with high humidity. When harvesting live and freshly cut trees, after laying it is necessary to compact them with a heavy load to avoid severe warping.

At natural drying, cracks will always form at the ends. To avoid cracking of the ends, they must be well painted with oil paint or impregnated with bitumen or hot drying oil, this will protect the pores of the wood. Processing of the ends must be carried out immediately after cross-cutting into the section. If the wood is very wet, it is necessary to dry the ends blowtorch and then start painting.

The ridges (trunks) must be cleared of bark (barked), only at the ends there should be collars up to 25 cm wide to avoid cracking. Peeling the bark is necessary to speed up drying and protect against beetles. Wood left with bark in a warm room and with a high level of humidity will very quickly begin to rot and become affected by fungi.

After drying by atmospheric method in warm weather, the wood moisture content will be from 12 to 18%.

There are other ways to dry wood.

Evaporation method

Evaporation (steaming) has been used since ancient times. The blanks were sawed into pieces, taking into account the size of the product, then ordinary cast iron was laid and sawdust from the same wood was added, filled with water and left in a heated and cooling oven at a temperature of 60-70 degrees. As a result of such actions, the process of “leaching” (evaporation of wood) occurs - the workpiece loses all its natural juices, is colored and takes on thick chocolate shades, with a rather pronounced natural pattern. Such a workpiece is easier to process, and after drying - there will be much less warping and cracking.

Waxing method

The wooden blank is dipped into a paraffin solution and left in the oven for several hours at a temperature of 40 degrees. Next, the wood is allowed to dry for several days, as a result of which it has the same properties as after steaming: a tinted surface with a clear texture pattern, does not warp or crack.

Method of locking in linseed oil

Dishes made from wood steamed in linseed oil are waterproof and practically do not crack even with everyday use. This method is still used today. The workpiece is placed in a container, poured linseed oil and steam over low heat.

Direct - according to the method, indirect - using electrical ones. The first method is accurate, the second method is fast.

Determination of wood moisture content according to GOST 17231-78 (GOST 16483.7-71)

The first method is direct (standard, old-fashioned, time-tested)

At the moment, there are two standards in force in Russia, both regulating the same method for determining wood moisture content:

1. GOST 17231-78 Split and round timber.
   Methods for determining humidity
   Download (downloads: 1226)
2. GOST 16483.7-71 Wood.
   Methods for determining humidity
   Download (downloads: 914)

Analogues of these standards can easily be found in the metrology of any post-Soviet country. Both documents (GOST 17231-78 and GOST 16483.7-71) regulate the procedure for sampling, testing and analysis methods for objective determination of the moisture content of wood, timber and firewood (everything from which a sample can be cut or sawn off for research). The method for determining humidity according to GOST 17231-78 and GOST 16483.7-71 is extremely simple and consists of systematic selection and subsequent drying of samples of the test material. In this case, the sample under study is kept in a drying cabinet until it is completely dry. After which, the weight of the wood under study is weighed and compared before and after drying.

Note According to GOST 17231-78 and GOST 16483.7-71, a sample is considered dry if its weight has not changed by more than 1% after being kept in a drying oven for 24 hours at a temperature of 101...103°C

Pros and cons

GOST methods for determining wood moisture content are very objective, but have one big drawback - they are cumbersome and slow. Wood moisture analysis can take up to 3 days while the samples dry. In addition, to analyze moisture content, it is necessary to cut a sample from the mass of the material being tested, which is absolutely unacceptable for determining the wood moisture content of finished products

Determining wood moisture content with a moisture meter

Method two - indirect (fast and modern)

In order not to bother with tedious selection and drying of samples, it is much easier and more convenient to “pok” the wood with a moisture meter. Moisture meter- This is a special electrical device for determining the moisture content of wood. The operation of the moisture meter is based on the principle of changing the electrical resistivity of wood depending on its humidity. The moisture meter has special needle-electrodes that need to be brought into contact with the wood being tested and simply press a button. The measurement result will immediately appear on the screen (or will be indicated by deflecting the arrow by the required amount if the device has a lever-type scale).

Pros and cons

Determining wood moisture content with a moisture meter is incredibly fast and convenient, applies to non-destructive method control and is therefore ideal for finished products. Alas, electric moisture meters give a big error

Measurement errors when determining wood moisture content

The error in measuring wood moisture content is

1. According to the methodology, no more than 1%
2. When using electric, within 2...10%

Why is there such a large error when using moisture meters:

1. Electrode needles penetrate locally, only to a depth of 5...15 mm. This results in superficial and local learning. wood material. As a result, there is a large percentage of error compared to standard GOST methods, where drying of samples occurs throughout the entire volume
2. Using the principle of changing the electrical resistivity of wood depending on its humidity gives an additional error. Because the value of the electrical resistivity of wood depends not only on its moisture content, but also on its density and resin content (for coniferous species). And since wood is a very variable quantity, the probability of error when measuring wood of different tree species in terms of density increases.
   That's why, Each type of wood has its own moisture content scale. Electric moisture meters are adjusted to the density of wood of a particular species, usually pine. For other types of wood, manufacturers of moisture meters provide tables or built-in calculators to calculate moisture content.
   But even such tricks do not allow reducing the measurement error to less than 2...3%, since the electrical resistivity of wood directly depends on the density of the wood, which can vary greatly even within the same wood species
   cm.

   Table of electrical resistivity of wood depending on the type of wood ( visual aid to an explanation of why tables are needed to recalculate humidity depending on the type of wood when using electric moisture meters)

   Wood species	Electrical resistivity (humidity 0%, 20°C, OM*cm)
   	across the grain	along the grain
   Pine	2,3*10 15	1,8*10 15
   Spruce	7,6*10 16	3,8*10 16
   Ash	3,3*10 16	3,8*10 15
   Hornbeam	8,0*10 15	1,3*10 15
   Cedar	2,5*10 16	1,9*10 15
   Larch	8,6*10 15	3,3*10 15
   Note These tables were found on the Internet, their reliability is unknown. However, even a superficial glance is enough to understand how much the electrical resistivity of wood, which is the basis for the operating principle of an electric moisture meter, can vary.

3. Measurement error depending on the type of wood when determining wood moisture content moisture meter decreases with increasing humidity and practically disappears at 100%. This is explained by the fact that in wood saturated with water, the electric current flows “directly” through the water, “ignoring” resistance

Units for measuring wood moisture content

No matter how the moisture content of wood is measured, its value is always expressed as a percentage of total mass. Wood moisture content is a quantitative indicator percentage moisture in it. It goes without saying that the moisture content of wood does not depend on the type of wood.

Free and bound moisture in wood

The main part of moisture (water) is contained in wood in intracellular and pericellular cavities and voids, channels, cracks, etc. But, besides this, water molecules are contained in a chemically bound state directly in the thickness.

Depending on the location of moisture in the wood pulp, it (moisture) is divided into two types - and

Free moisture

Free moisture is moisture that is found in the intracellular and intercellular space, as well as in the cavities and voids of wood. Free moisture is also called “capillary”. Free moisture is retained in the wood layer due to simple mechanical bonds and is easily removed from it during normal drying. Free moisture is water that wood can absorb and then release when drying.

Associated moisture

Bound moisture is a specific term. Bound moisture is moisture that is located inside the wood cell wall material, directly in the

Direct - according to the method, indirect - using electrical ones. The first method is accurate, the second method is fast.

Determination of wood moisture content according to GOST 17231-78 (GOST 16483.7-71)

The first method is direct (standard, old-fashioned, time-tested)

At the moment, there are two standards in force in Russia, both regulating the same method for determining wood moisture content:

1. GOST 17231-78 Split and round timber.
   Methods for determining humidity
   Download (downloads: 1226)
2. GOST 16483.7-71 Wood.
   Methods for determining humidity
   Download (downloads: 914)

Analogues of these standards can easily be found in the metrology of any post-Soviet country. Both documents (GOST 17231-78 and GOST 16483.7-71) regulate the procedure for sampling, testing and analysis methods for objective determination of the moisture content of wood, timber and firewood (everything from which a sample can be cut or sawn off for research). The method for determining humidity according to GOST 17231-78 and GOST 16483.7-71 is extremely simple and consists of systematic selection and subsequent drying of samples of the test material. In this case, the sample under study is kept in a drying cabinet until it is completely dry. After which, the weight of the wood under study is weighed and compared before and after drying.

Note According to GOST 17231-78 and GOST 16483.7-71, a sample is considered dry if its weight has not changed by more than 1% after being kept in a drying oven for 24 hours at a temperature of 101...103°C

Pros and cons

GOST methods for determining wood moisture content are very objective, but have one big drawback - they are cumbersome and slow. Wood moisture analysis can take up to 3 days while the samples dry. In addition, to analyze moisture content, it is necessary to cut a sample from the mass of the material being tested, which is absolutely unacceptable for determining the wood moisture content of finished products

Determining wood moisture content with a moisture meter

Method two - indirect (fast and modern)

In order not to bother with tedious selection and drying of samples, it is much easier and more convenient to “pok” the wood with a moisture meter. Moisture meter- This is a special electrical device for determining the moisture content of wood. The operation of the moisture meter is based on the principle of changing the electrical resistivity of wood depending on its humidity. The moisture meter has special needle-electrodes that need to be brought into contact with the wood being tested and simply press a button. The measurement result will immediately appear on the screen (or will be indicated by deflecting the arrow by the required amount if the device has a lever-type scale).

Pros and cons

Determining the moisture content of wood with a moisture meter is incredibly fast and convenient, it is a non-destructive testing method and is therefore ideal for finished products. Alas, electric moisture meters give a big error

Measurement errors when determining wood moisture content

The error in measuring wood moisture content is

1. According to the methodology, no more than 1%
2. When using electric, within 2...10%

Why is there such a large error when using moisture meters:

1. Electrode needles penetrate locally, only to a depth of 5...15 mm. Because of this, a superficial and local study of wood material is obtained. As a result, there is a large percentage of error compared to standard GOST methods, where drying of samples occurs throughout the entire volume
2. Using the principle of changing the electrical resistivity of wood depending on its humidity gives an additional error. Because the value of electrical resistivity of wood depends not only on its moisture content, but also on its density and resin content (for conifers). And since wood is a very variable quantity, the probability of error when measuring wood of different tree species in terms of density increases.
   That's why, Each type of wood has its own moisture content scale. Electric moisture meters are adjusted to the density of wood of a particular species, usually pine. For other types of wood, manufacturers of moisture meters provide tables or built-in calculators to calculate moisture content.
   But even such tricks do not allow reducing the measurement error to less than 2...3%, since the electrical resistivity of wood directly depends on the density of the wood, which can vary greatly even within the same wood species
   cm.

   Table of electrical resistivity of wood depending on the type of wood (a visual aid to explain why tables are needed to convert humidity depending on the type of wood when using electric moisture meters)

   Wood species	Electrical resistivity (humidity 0%, 20°C, OM*cm)
   	across the grain	along the grain
   Pine	2,3*10 15	1,8*10 15
   Spruce	7,6*10 16	3,8*10 16
   Ash	3,3*10 16	3,8*10 15
   Hornbeam	8,0*10 15	1,3*10 15
   Cedar	2,5*10 16	1,9*10 15
   Larch	8,6*10 15	3,3*10 15
   Note These tables were found on the Internet, their reliability is unknown. However, even a superficial glance is enough to understand how much the electrical resistivity of wood, which is the basis for the operating principle of an electric moisture meter, can vary.

3. Measurement error depending on the type of wood when determining wood moisture content moisture meter decreases with increasing humidity and practically disappears at 100%. This is explained by the fact that in wood saturated with water, the electric current flows “directly” through the water, “ignoring” resistance

Units for measuring wood moisture content

No matter how the moisture content of wood is measured, its value is always expressed as a percentage of the total mass. Wood moisture content is a quantitative indicator of the percentage of moisture content in it. It goes without saying that the moisture content of wood does not depend on the type of wood.

Free and bound moisture in wood

The main part of moisture (water) is contained in wood in intracellular and pericellular cavities and voids, channels, cracks, etc. But, besides this, water molecules are contained in a chemically bound state directly in the thickness.

Depending on the location of moisture in the wood pulp, it (moisture) is divided into two types - and

Free moisture

Free moisture is moisture that is found in the intracellular and intercellular space, as well as in the cavities and voids of wood. Free moisture is also called “capillary”. Free moisture is retained in the wood layer due to simple mechanical bonds and is easily removed from it during normal drying. Free moisture is water that wood can absorb and then release when drying.

Associated moisture

Bound moisture is a specific term. Bound moisture is moisture that is located inside the wood cell wall material, directly in the

Wood - affordable, environmentally friendly pure material, widely used in the construction and decoration of buildings. However, many people refuse it for the reason that over time the wood begins to warp and cracks appear in the structures. This happens as the wood dries. This problem can be avoided if you work with dry material. The moisture content of lumber is regulated by a number of documents, in particular SNiP II-25-80.

In order to obtain a high-quality and reliable structure, it is necessary to use only dry wood during construction.

But how can you find out the moisture content of wood when purchasing? This is quite difficult to determine by eye. Only a specialist with extensive experience can determine by certain signs whether the wood is wet or dry, but he will not give an exact percentage. Some conclusions about moisture can be drawn when processing lumber. If the shavings removed by a plane are plastic and bend, then the wood is damp; if it crumbles, it is dry. Construction regulations require an exact figure, and to determine it there are a number of methods, the most used of which are calculation by mass and calculation using special device- moisture meter.

Calculation of wood moisture content by mass

Figure 1. Density table various types wood

It is known that various breeds trees have different densities. But the density depends not only on the species, but also on the moisture content of the lumber: the drier the wood, the lighter it is. Data on the most common species are presented in the table in Figure 1. Knowing the volume and mass, you can calculate the density, find it in the table for a given tree and thus determine the moisture content of the wood. It's quite simple and quick way determination of humidity. However, it should be taken into account that the density of trees, even of the same species, but growing in different climatic zones, may vary, so errors in calculations cannot be avoided.

For more precise definition moisture content of lumber is being studied. For testing, a sample measuring 20x20x30 mm is taken. The sample is cut from the lumber at a distance of at least 30-50 cm from the edge of the board. It is weighed on a scale with an accuracy of 0.1 g and placed in a drying cabinet with a temperature of 101-104 ° C. After 6 hours, the sample is removed from the cabinet, re-weighed and put back in the cabinet. Subsequent weighings are carried out at intervals of 2 hours. The weighing results are recorded in a journal. If the difference in mass based on the results of two weighings does not exceed 0.1 g, then the wood is considered absolutely dry.

Calculation of wood moisture content.

The absolute humidity of the material is calculated using the formula:

W=(m-m0)/m0×100(%),

where W is the humidity, m is the mass of the sample at the first weighing, m0 is the mass of the same sample after complete drying.

It is necessary to consider how to determine the moisture content of a sample using an example. We can assume that before drying it weighed 98.76 g, after drying - 65.81 g. Then W = (98.76-65.81)/65.81x100 = 50.1%.

To obtain a reliable result, it is necessary to conduct a study with several samples. It is not recommended to keep resinous rock samples in a drying cabinet for more than 20 hours.

This method of determining wood moisture content complies with GOST 16483.7-71, but it takes a lot of time and requires special laboratory equipment.

Determining humidity using a moisture meter

A moisture meter can be used to determine the moisture content of wood.

Scientific and technological progress manifested in all areas human activity, did not stand aside in relation to such an issue as determining the moisture content of wood. Today, a moisture meter will not surprise anyone. The cost of this portable device depends on the manufacturer, model and set of functions, but it is not so high that you can refuse it convenient device. Moisture meters are available in almost any warehouse where lumber is stored or sold. And therefore, measuring humidity turns into a matter of minutes.

The principle of operation of a moisture meter is based on measuring resistance when an electric current is passed through wood. The device has needle sensors that are buried into the lumber along the grain. When you press the measurement button, a current is passed through them, and the result, already converted into a humidity indicator, is instantly displayed on the display. The measurement error of modern moisture meters is no more than 1.5%. It should be understood that the result is reliable only for the place where the needles are deepened. To judge the condition of the lumber as a whole, it is necessary to take as many measurements as possible along the entire length and width of the board.

Acceptable wood moisture content according to GOST.

A number of models have a long conductor connecting the device to needle sensors. This allows you to measure the moisture content of wood remotely while drying it in the chamber. In this case, sensors are inserted into boards located in the middle of the stack. The device itself is placed outside the chamber. When taking measurements, it is necessary to make corrections for temperature. The remote method is convenient for controlling the wood drying process, but it should be recognized that it often gives distorted results. This happens for two reasons: due to heating of the sensor needles, which transfer it to the wood in places of deepening, and due to the violation of the tight contact of the sensors due to drying of the wood.

In cases where even minimal damage to wood is extremely undesirable, for example, when it comes to furniture parts, the moisture content of wood can be determined with a non-contact moisture meter. It does not have needles, but is simply applied to the surface of the lumber. The operating principle of the device is based on measuring length electromagnetic waves, which will differ depending on humidity. When measuring with such a moisture meter, the wood should be determined by its species.

Drying wood

Damp wood is not a death sentence. It is quite possible to bring it to a workable state even without drying it in a chamber. Moreover, atmospheric drying is recommended for any purchased lumber.

Drying wood comes down to its proper storage. To do this, set up a place in a draft, protected by a canopy from precipitation and direct sunlight. The last condition is due to the fact that under the sun the surface of the boards quickly heats up and dries, while the bottom remains wet. Because of this, tension arises, the wood warps and cracks.

Logs with a height of at least 0.5 m from the ground level are installed under the stacks. The surface of the base must have a strictly horizontal orientation. To avoid sagging of the boards, the distance between the support points should not exceed 1.5 m. Between the rows of boards, spacers made of softwood 25-40 mm thick are placed perpendicular to them, and after 1.0-1.5 m - spacers 100 mm thick. 150 mm. This will ensure better air circulation. You cannot stack boards that have different humidity levels in one stack: wood is hygroscopic, and dry lumber will pick up moisture from wet lumber.

The time required for drying to 18-22% moisture varies from 9 to 40 days. It depends on climatic conditions, time of year and material thickness.