When performing construction work, dry wood is taken for the production of furniture and decorative products, since the wet material “leads” after processing, which spoils the decor of caskets, picture frames, photographs. Other structures are at risk - doors, doorposts, floors, stairs.
Due to the large volumes, the moisture level in the wood is difficult to determine, the experience of a specialist is important - all measurements are carried out manually, and the employee can skip (accidentally or intentionally) part of the blanks. And at large woodworking enterprises, selective measurements are made, by which they find out how many percent of moisture in the batch (5-20 pieces, according to the data obtained, the average indicator is calculated). The moisture content of wood in enterprises is determined in stages.
It is likely that the part may not be dry enough, and this will cause difficulties for specialists working with the material - craftsmen, furniture makers. Only dry wood is needed, so you have to independently determine its condition.
Execution methods
There are only 2 ways to find out the water level in wood:
You can do this using tools. For accurate measurements use a special device - a moisture meter. It is designed to determine the level of moisture content in different conditions and for any materials.
It is possible to measure the moisture content of wood by its weight; it is possible to carry out calculations at home.
There is a GOST that allows the level of moisture content in wood for certain purposes after processing. (GOST 17231-75 and GOST 16483.7-71). Documents are valid in the CIS countries. They regulate the methods of selecting probes, guidelines for measuring humidity, analysis and interpretation of the information received.
The preparation process and the work itself are simple: samples are taken from the batch, which are placed in an oven with specified conditions. This is temperature, humidity, and other factors. After a full cycle of operation of the cabinet, the sample is taken out and weighed, comparing the moisture content of the wood before and there. GOST provides for tolerances (the error of the permissible deviation from the set values).
If the workpiece has been lying in the warehouse for a long time (even after drying), then equilibrium moisture is collected. This indicator for the tree is the value that the environment has. For example, during long-term storage in a warehouse, a tree will pick up or give up moisture so much that as a result, the humidity of the logs or boards will be equal to this indicator in the room. Therefore, there is a separate GOST, which regulates the moisture rate. Storage conditions for the material must be observed.
Weight measurement
This option is the most accurate, that's why humidity is determined in accordance with GOST. The method can be changed at home. It does not require special equipment. However, knowledge of physics and some reference data are required in accordance with GOST. It is recommended that you familiarize yourself with GOST before taking measurements to have an idea of humidity, what it affects, what value a standard number has, and also for obtaining reference data.
The method is based on the fact that any material has a density. Different types of wood differ in this indicator. At the same time, the natural density of wood is much lower than the real one - the tree absorbs moisture. Dry wood is lighter than wet. Having obtained the values of the volume and mass of the workpiece, you can check or calculate the humidity. This option is more reliable than the simple use of a moisture meter.
It is important to correctly take the initial density data for calculations, because even with the same tree species that grows in different climatic conditions, it is different. This gives an error.
In order to carry out the calculations, it is necessary to take a 2 × 2 × 3 cm blank, which is cut from the edges of the board at a distance of about 0.3–0.5 meters.
Anyway, from which edge of the board the material is cut off. The next step is weighing. It must be produced on very accurate scales in order to obtain a mass index of up to 0.1 grams. After that, the volume and density of the material are calculated.
Calculations based on data received
For comparison with the calculated data, the natural density of wood is taken. The difference between the calculated and natural values will indicate that the tree is wet. To determine the exact value, the workpiece is placed in an oven at a temperature of 100 ° C (you can use an oven in everyday life) for a quarter of a day. After that, the workpiece is removed, re-measured and weighed.
The calculations are performed as follows:
W = (m-m0) / m0 x100%, where: m is the mass of the workpiece to the oven, m0 is the mass after removal from the dryer, W is the humidity value.
The disadvantages of this method include a long time for obtaining and processing information, the need to select the exact values from the reference materials (natural density). However, the result will be accurate.
Measuring instruments
To determine the moisture content of wood, you can use a device that allows you to find out approximately how many percent of the water is contained in the material. The only requirement for such work is the presence of a moisture meter, which is quite expensive. Most enterprises have such a device at their disposal and, if agreed, all measurements can be made.
The principle of operation is based on the phenomenon of electrical conductivity in various environments. The device has two needle sensors, which should be inserted into the workpiece at the same depth, after which current passes through them. At the same time, the standard of dry wood is already laid in modern devices, which allows you to check the data with the set values for a particular breed. The whole operation takes about a minute.
The disadvantages of this method include a high error. For the best devices, it is 1.5–2%, for the majority it can reach up to 3-4%. In addition, it is difficult to stick the needles at the same depth, which gives significant deviations.