Wooden products made from oak belong to the premium class. The wood is used to make furniture and interior parts. Oak is rarely used for construction, as the price of the material is high. In order for the wood to last longer and not crack over time, it must be properly processed. One of the critical stages of processing is drying. Let's talk about how to dry oak at home and in production in more detail with our readers.
To dry oak in large industries, drying chambers and the vacuum method are used. At home, these methods are not available, since they require special equipment, which is expensive. Another effective method is under the influence of electric current, but in Russia it is practically not used due to its high cost.
- Oak wood dries out easily. This means that when the humidity drops below 7%, the product will begin to crack, both inside and out.
- The longest time will be required to dry fresh wood with a moisture content of 25%.
- If you start drying immediately by raising the temperature above 50 degrees, the internal capillaries of the wood will begin to collapse and the product inside will become covered with cracks. This will not affect the appearance, but the fragility increases by 75%.
- High-quality drying is carried out only by maintaining uniform temperature and humidity.
How to properly dry oak is planned, since the final percentage of moisture depends on the tasks and purpose of use of the product. The tasks of drying oak can be considered in the table:
Complete drying is used only in the manufacture of furniture or small interior design elements. For medium and large sized lumber, processing for transportation and storage is sufficient.
Several available methods for preparing wood
For home processing, the following methods are used:
- Dry the oak tree in advance. The required tree is marked in advance on the plot and in the spring the bark is removed from it, right from the roots to a height of 20–30 cm. The juices will not be able to reach the crown in the required volume and the oak will dry out. In the fall it is cut down and cut into timber.
- Natural drying. Oak wood of natural moisture content is purchased. The material is laid out under cover on the site, so that the wood is blown from all sides. The material is laid on chocks in layers. The distance from the ground to the bottom row is at least 300 mm. Drying time is 3–6 months, depending on climate and humidity.
- Drying small items indoors. The oak product is wrapped in newspaper in 5–8 layers and covered with PVC film on top. Holes are made in the film for ventilation. The product is placed on the windowsill above the battery. Once an hour the package is turned over. The process takes 2–3 days. This is the most affordable way to dry a wooden product at home.
Drying large oak timber at home is difficult. The most affordable option is outdoors. But wood is hygroscopic and easily absorbs moisture from the air. That is, if drying is carried out during the rainy season, the process becomes useless. The easiest option is to harvest wood from the winter forest. In winter, at temperatures below -20, oak wood acquires moisture equivalent to chamber drying. Therefore, products from winter forest do not require additional preparation.
Methods in production
When preparing wood in production, chamber drying is used. The oak is placed in a special sealed convection chamber. Under the influence of high temperatures and ventilation, excess moisture gradually evaporates and the wood dries. The process is carried out in three stages:
- Wood heating.
- Drying.
- The oak cools and acquires the desired humidity.
The camera is constantly monitored, because if the process is disrupted or a mistake is made, the product begins to twist or crack. The kiln drying process lasts from 1 to 3 weeks. But many manufacturers shorten the process and the wood does not dry out completely.
It is important to check the moisture content of the wood from the inside before purchasing. For this, a manual moisture meter is used.
The vacuum drying method is carried out in special chambers, where, under the influence of atmospheric pressure and high temperatures, the minimum moisture content of lumber is achieved. The vacuum method is used in production for preserving wood, since in the chambers the product is additionally treated with antiseptics. The compounds penetrate deep into the wood under the influence of vacuum. This increases shelf life and improves product quality during transportation. The vacuum method is difficult to reproduce at home, as special equipment is required.
Chamber drying, due to its high cost, is gradually fading into the background. A new method is replacing it - infrared preparation. Infrared treatment reduces drying time and saves electricity. At the same time, the effect on oak wood is uniform and soft, and does not destroy the product from the inside and outside. Impact infrared heat makes it possible to obtain any percentage of humidity.
Know-how - preparation using infrared light
Infrared batteries can be used at home and in factories. The process requires cassette forms, which are located inside a special frame of metal stacks. The size of the battery depends on the number of cassettes, so 2–3 pieces are enough for home use. The amount of material processed simultaneously does not matter; the main thing is to position it correctly and direct the light. Treatment up to 6–12% is carried out within 6–7 days. To obtain 20–25% humidity, 2–3 days are enough.
Oak lumber after infrared exposure has the following characteristics:
- Has a specified humidity.
- The fibers do not deform, so there is no internal stress or microcracks.
- Externally, oak remains natural (color and shape do not change), as during atmospheric drying.
The rules for using an infrared battery are simple and the operator does not need to have any skills or experience. The battery is connected to a simple single-phase outlet and current consumption is minimal. To dry 1 cube of oak you will need 200–350 kW.
Humidity is checked during infrared exposure with a hand-held moisture meter. As soon as the indicators meet the set objectives, the dryer turns off. Immediately after the process, the dried lumber can be used in work. The process is shown in more detail in the video:
Since oak is capricious and does not react well to temperature changes, the optimal drying methods are natural or infrared. They are suitable for home use and do not require any special preparation. In large industries, chamber drying or vacuum preservation is used. Which significantly reduces time and extends shelf life.
- Methods
- Grandfather's secrets
- Natural drying method
- Kiln drying
- Rotational method
- Conductive method
- Atmospheric method
- Liquid drying
Drying wood is a mandatory stage in lumber processing. Excess moisture is removed by evaporation, and the natural material reaches the required condition before use. Woodworkers know that without this technological process the wood will not be strong. It will warp, crack and rot, and these are serious problems. If you want to get the effect of working with wood, you need to know how to dry wood correctly and in what ways to do it.
Methods
There are several methods for drying harvested timber with your own hands, and all of them are aimed at obtaining high-quality construction raw materials with the required physical parameters. Regardless of which method is chosen, before the wood is dried, it is carefully inspected for defects.
Grandfather's secrets
Evaporation technology came to us from the past, and it consists of immersing boards in a container filled with hot water (about 70˚C), on top of which sawdust was poured. After such steaming, the material did not crack, and the wood itself additionally gained elasticity and a dense structure. There is a known method of waxing, when the workpiece was dipped into liquid paraffin heated to 40 °C for several hours. After this procedure, the board did not warp and additionally acquired a beautiful dark tone.
The process of drying wood by waxing was used in the production of tableware. The master had only to decorate the cups and bowls with patterns, and then cover them with a protective layer on top. The finished products were so durable that even with temperature changes they retained their original appearance, and not a single crack could spoil the master’s fruits.
Natural drying method
Natural drying of wood demonstrates how to dry wood at room temperature without using expensive equipment. If we are dealing with a ridge covered with bark, then the top covering is not removed, but notches are made across the trunk. You can leave strips of bark no more than 10 cm thick along the edges of the ridge.
Natural drying of lumber guarantees the absence of cracks in hardwoods such as , or , however, it is still better to tar the ends of the logs or .
The room in which the wood is dried must be dry and well ventilated. Make sure it's straight Sun rays do not get on the log, otherwise its outside surface will overheat excessively, and the inside will retain moisture, which is why the material is highly likely to crack. The correct way to dry lumber involves stacking it on a stand. The distance must be at least 60 cm from the ground, and ventilated gaps must be provided between the workpieces.
To the question whether it is possible to properly dry boards installed on the edges, the answer is categorical - no. This is a fairly quick home drying method, but it often warps and cracks the timber. The same applies to drying wood at the ends, after which the timber has to be trimmed. This must be taken into account when planning the required length of the workpieces. Complete drying of any other type of wood in this way lasts at least two to three years, and this is a serious drawback, because the master does not always have time. The undeniable advantages of natural drying include its simplicity and lack of financial costs. If you are not satisfied with the timing of the manipulation, and the timber needs to be dried quickly, albeit at additional costs, you can use.
Kiln drying
Chamber drying of lumber is an advanced modern methods allowing you to get excellent results quickly. This can be done if you are ready for financial investments. The advantage of accelerated drying of wood, which is carried out in industrial conditions, is that you can easily achieve the desired humidity parameters. The chamber process is carried out as follows: carts with lumber are fed into a drying unit, where, under the influence of a gaseous environment, liquid is removed from the wood structure. The drying mode can vary depending on the requirements and at the discretion of the master.
PAP chambers are metal drying chambers, inside of which special equipment is installed that provides aerodynamic heating. According to the technology, steam is regularly pumped into the chamber under low pressure. Despite the simplicity of this method, it cannot be called cheap, due to the high cost of electricity, which significantly increases the cost of the processed material.
Rotational method
There is another effective method in which it is possible to dry the timber using centrifugal force. Boards stacked on a platform are placed inside a heated room. Centrifugal force ensures uniform movement of moisture from inside the log to its ends and outer surfaces.
Intensely moving hot air allows you to quickly dry the lumber to the desired condition, and lamps or slabs designed for such purposes act as heat sources. Rotary or infrared drying, in which radiation penetrates wood to a depth of 12 cm, can be carried out in just a few minutes, which makes this method noticeably superior to chamber drying, while atmospheric drying of wood, which lasts for several years, remains far behind in terms of efficiency.
Conductive method
If you need to remove moisture from a thin material such as plywood or veneer, it is better to prefer conductive (contact) drying, which is usually done using a press. The sheets are clamped between plates heated to a certain temperature, which are in direct contact with the material being processed - hence the name of the method. Contact or vacuum drying of wood allows you to do without fans. This saves energy. No need for a humidification system or numerous thermometers. As auxiliary equipment in vacuum installations, humidity sensors are used, which are controlled externally. The absence of aggressive temperatures and the gentle process of moisture evaporation protects the dried wood from deformation.
Atmospheric method
Atmospheric drying – good example how to dry boards at home without additional energy costs.
The effectiveness of atmospheric drying directly depends on a number of factors, such as climatic conditions, time of year or air temperature and humidity. To install storage devices you will need space, as well as compliance with simple rules:
- the dryer in a barn or under a canopy should be intensively ventilated;
- wooden material is stored in several rows with mandatory technological gaps;
- To prevent the tree from moving or warping, it is usually pressed from above with something heavy.
In dry weather conditions, atmospheric drying will allow you to achieve 12–48% humidity, and to obtain more significant indicators, the room method can be used in a heated room.
Liquid drying
Rapid drying in liquids is an additional measure before treating workpieces with antiseptic agents. Water-salt solutions or hydrophobic compounds (sulfur, paraffin, liquid metals) can be used as an active agent here.
The duration may depend on the power of the heat exchanger installed in the drying chamber and the intensity of heat redistribution within the fibers, depending on the type of wood. The board is immersed in liquid and brought to a boil, maintaining the optimal temperature until free moisture is removed, which takes an average of 3 to 20 hours.
In addition to these methods, there are a number of other methods (radiation, induction, microwave, refrigeration), but none of them is possible at home due to the specifics of the equipment and its high cost. As for the drying time, with accelerated artificial methods the timber dries in just a couple of hours. Properly dried wood will serve as a finished product for many decades, while wood with excessive moisture will quickly become unusable, so such an important technological process cannot be ignored.
At the very beginning of the process, the air has quite high humidity and low temperature. The higher the initial moisture content of the tree, the more moisture there should be in the air entering the chamber. This is necessary in order to prevent cracking of the material. As the rock dries, the air temperature is gradually increased, while the moisture content in it, on the contrary, is reduced.
There is a strict relationship between air humidity and moisture content in the material. It can be determined using a special device - a psychrometer, which is used to determine the humidity and temperature of the air in drying chambers. The latter are called sushila. There are various methods for drying wood.
The factory method involves the use of special drying chambers. These are periodic steam-air dryers with reverse circulation. The resulting material, unloaded from there, is kept in the production workshop for two to three days. At this time, the material is normalized, that is, it is released from surface and internal stresses acquired during the drying process.
There are also chambers for drying wood material. In such periodic devices, a special smokeless gas is used to get rid of unnecessary moisture.
It is obtained by burning raw wood waste in furnaces. With the help of a high-pressure axial fan, through special gas ducts, it is supplied to the stacks of lumber. The design of the system assumes the presence of a steam humidifier.
In the woodworking industry they use gas apparatus, operating on natural gas. They are equipped with a firebox, the temperature in which during combustion reaches 1300°C. But before entering the dryer, the mixture circulates and cools, acquiring a temperature of 100 degrees by the time it enters the chamber. The working mixture is smokeless. If the operation of such a chamber is well adjusted, then the lumber dried in it remains light. Each can accommodate four large stacks of boards. They are also used for ordinary, routine drying of coniferous wood.
For speed drying building material Electric dryers are used, which use high-frequency currents. This procedure does not last long - the drying time is only a few hours, and its quality is high. The wood dries evenly: without flaws or cracks. The amount of defects with this drying method turns out to be significantly less than with the gas and steam methods - its figure is less than five percent.
Features of heating dielectrics and semiconductors (wood also belongs to them) in electric field high frequencies are that the temperature of the entire processed material increases noticeably in a short period of time. A wet board can be heated to 100 degrees throughout its entire thickness in three minutes. The power of the current absorbed by the material is regulated by the parameters of the electric field (its change through adjustment).
Home drying of wood
In addition to industrial methods of drying wood, there are also home ones.
Using a microwave
The advantages of this method are that when it is used, tiny cracks do not form in solid wood, which can turn up to one and a half centimeters of material from each end into waste, and in some cases even break the workpiece into pieces. Under the influence of microwave heating, changes occur in the lignin fibers, due to which an object dried in this way loses its sensitivity to sudden changes in humidity.
For the drying procedure, a not too powerful, budget microwave model without unnecessary options is suitable. The main thing is that it has a low power mode. Usually it corresponds to the “defrost” mark. The chamber must be large enough to accommodate crafts or wooden pieces. Often the chamber is larger in width than in depth.
Microwave drying of wood: technology
It is more convenient to dry individual pieces entirely; some are better cut into pieces. If it is already known what they are intended for, then they are cut to the size of future products, with an allowance. It is allowed to dry a pre-processed workpiece, which must also have at least a small allowance. It should be remembered that the product may become deformed during the drying process. A round object can become more oval.
Anyone who often works with wood gradually gains experience. Craftsmen can guess what kind of reaction to expect from which type of wood, how exactly which type is deformed, and make the appropriate allowance. If you leave a processed raw piece on the table, it may burst.
During breaks in work (for example, when carving) or before drying in the microwave, it is necessary to put the product in a plastic bag.
Microwave: drying at home
Before starting the procedure, the workpiece is weighed and the weight is recorded. The item, wrapped in a plastic bag with holes made, is placed in the middle of the oven, and the minimum power is set. Processing time depends on the size of the item. Then the workpiece is cooled directly in the bag and warmed up again. The condensate from the bag is drained and the item is weighed.
The entire cycle is repeated several times until the mass becomes constant and stops decreasing.
If the item cracks in the first attempt, it is necessary to either reduce the power further or seal the ends of the workpiece. The mouthguards are wrapped in newspapers before being placed in the bag. You can also do this with other workpieces: this will reduce the likelihood of wood cracking.
After cooling, before the next cycle, the newspapers are replaced with new ones. If there are resin pockets in the array, the latter can boil, break it, and stain the oven with resin. Wrapping in paper will also help here.
If you continue the process of heating already dried wood, it can char and even catch fire.
Natural air drying of wood
This is an affordable and extremely simple method. The boards are stacked under a canopy to prevent precipitation and sunlight from falling on them. A special flat base must be prepared for them, for the equipment of which rails, logs, thick pipes or bars can be used. Lumber is laid across this base.
There should be a distance of 0.3 m between the ground and the bottom layer of boards. It is better to cover the ground under the stack with sheets of roofing material, straw or hay. The wood takes quite a long time to dry: this process can take up to several years. In warm weather, the process is more active.
The ends of the forest are covered with a special mixture containing lime. The sides of the stack are protected from slanting rain and strong winds. Special measures are taken to prevent rapid drying and cracking of the material. Spacers are laid across the boards, between the layers of dried wood, at a distance of a meter from each other: the outermost ones are located flush with the ends of the boards in the stack.
With this method of drying wood with your own hands, mandatory cracks form at the ends of the boards. For this reason, the length of the blanks should be slightly larger than the planned products. After all, after drying is complete, the cracked ends of the boards will have to be cut down. With such drying, carried out in dry and warm conditions, the remaining in - is the largest online store selling furniture, lamps, interior decor and other goods for a beautiful and cozy home.
When purchasing wood, we are usually interested in its moisture content. Nobody wants to buy raw lumber, since its use as a construction or ornamental material is justified only in rare cases (for example, for pouring concrete).
Therefore, logging and wood processing enterprises usually trade in wood that has already undergone the drying process.
What is wood moisture content
In production construction work and for the manufacture of wooden products, wood with a moisture content of no more than 23% is usually used.
In practice, several types of wood are distinguished depending on its moisture content:
- wet – humidity more than 23%;
- atmospheric-dry – humidity 18 – 23%;
- air-dry (after artificial drying) – humidity 12 – 18%;
- room-dry – humidity 8 – 12%.
The lower it is, the less susceptible it is to rotting. In addition, after drying, almost all properties of wood that are important for use are improved:
- its strength increases;
- deformability decreases;
- , sanding, gluing, painting;
- indicators such as electrical conductivity and heat capacity decrease, the calorific value increases;
- The density of wood is directly related to its moisture content; the drier the wood, the lighter it is.
There is also the concept of equilibrium moisture content of wood. This means that at certain values of air humidity and temperature, the moisture content of wood remains unchanged and tends to a certain value.
If these parameters change, the wood will either release moisture into the surrounding atmosphere or absorb it until the humidity reaches a new certain value.
Thus, during the drying process of wood, its moisture content is deliberately reduced to equilibrium values, depending on where and how the lumber will be used.
Wood drying methods
All methods of excess moisture can be divided into the following types:
- natural drying;
The first method is known to everyone. It consists of putting the lumber in a stack, where the rows are interspersed with spacers, putting a covering on top to protect it from precipitation, and leaving it to lie in the air. Due to constant ventilation of the stack, the wood loses moisture and dries out.
The second method is to dry the wood in special drying chambers., where you can regulate the air temperature and humidity. But this option is suitable for drying and is used mainly in woodworking enterprises.
What methods of drying wood can you use at home?
Even the ancient craftsmen knew how to perfectly dry wood to the desired condition. Many methods were used for this, some of which are still relevant today.
There is such an unpleasant property of wood as cracking when drying. However, not all types of wood are equally susceptible to cracking:
- alder, linden, birch, poplar and aspen - dry almost without cracks;
- larch, spruce, cedar, fir, pine - crack, but not too much;
- beech, hornbeam, maple, ash, oak are subject to severe cracking.
This is a circumstance for drying each type of wood.
One of the well-known folk drying methods is drying the tree directly on the root. It is carried out as follows:
- At a distance of about half a meter from the ground, the bark is removed in a ring along the entire circumference of the chosen trunk. The width of the ring is approximately 1 - 1.5 m. Reducing the width of the ring leads to an increase in drying time.
- The removed bark stops the flow of moisture into the tree crown, while the foliage quickly consumes the remaining moisture in the trunk, thereby dehydrating it.
- The readiness of the wood is determined by the degree of drying of the foliage.
- When it is completely dry, the trunk can be cut down and used.
Drying the cut trunk:
- The tree is cut down and, leaving a ring of bark on the trunk 0.7 - 1 m wide from the point of cutting, the rest of the trunk is left without bark. The crown is not touched.
- The foliage remaining on the trunk quickly draws moisture from it, effectively drying out the wood.
- After 2 - 3 weeks, the trunk can be sawed and folded under a canopy for final drying.
Drying is carried out in the same way as in enterprises: a flooring is built on a flat, dry area, on which lumber is stacked. The top row is laid with a slope and covered from precipitation.
To protect the ends of the material from rotting, they are covered with lime, treated with a solution of table salt or coated with liquid glue.
This method allows you to get rid of 75% of the moisture in the wood, but is very slow:
- coniferous and soft hardwoods dry out within 1 – 1.5 years;
- hardwoods – more than 2 years.
Drying wood in a closed, ventilated area. To do this, you can use a spacious barn or a fairly high attic. Here there is a stack of wood laid on pads than on the street. It is only necessary to ensure constant ventilation of the room.
Drying lumber on a cement floor. This method is sometimes used to dry small volumes of lumber. It is laid out in one row on a cement floor and the boards are turned over from time to time. The method is based on the ability of cement to draw moisture from other materials upon contact.
Drying small wooden pieces and parts using newspapers:
- the workpiece is tightly wrapped in dry newspaper and placed in a plastic bag, which is tightly wrapped.
- The bag with the workpiece is placed in a warm place.
- When the newspaper becomes damp, it is replaced with dry one and the process is repeated until the workpiece reaches the required humidity.
This process usually lasts about 3 – 4 weeks. As the wood dries, the newspapers have to be changed less and less often. To speed up the process, the workpiece can be wrapped in a thicker layer of paper, but here, drying too quickly can lead to cracks.
Drying workpieces using sawdust or straw: the workpieces are covered with a thick layer of sawdust or dry straw and placed under a canopy. Sawdust and straw take moisture from the wood, but there is no need to change them, they quickly dry out on their own.
Drying by steaming and boiling wood.
These are more complex methods, but they can be successfully used at home.
The steaming method is used to replace the moisture contained inside the wood with vegetable oil. To do this, place the workpiece in a container with any vegetable oil and heat it over low heat for 6-7 hours.
The steaming time depends on the size and thickness of the workpiece. In former times, wood intended for making wooden utensils was processed in this way. And the dishes turned out to be very durable, without cracks.
The digestion method involves keeping the workpiece for a long time in a boiling salt solution (2 tablespoons of salt per 1 liter of water). Salt expels cell sap from wood, replacing it. The saline solution itself is expelled from the wood much faster than water and without “serious consequences.”
After boiling for 8 - 10 hours, the workpiece is removed, tied with a rag and placed in a dry place for 2 weeks. When using boiling, you can simultaneously change the color of the wood. To do this, pine sawdust is mixed into the saline solution. If the workpiece is large, then after drying in air, the digestion is repeated, then the workpiece is dried again. All this time the harness is not removed from her.
If the products were made from damp wood, they can be dried using dry, clean river sand. To do this, the workpiece is placed in a container of suitable size, sprinkled with sand on all sides and placed in the oven.
We looked at the best ways to dry wood at home. They all require time and patience. So if you urgently need a dry blank or several boards, then it would be more advisable to purchase blanks of the required moisture content.
If you are a home craftsman and you have nowhere to rush, traditional methods drying will be just right. After all, they almost 100% guarantee proper drying of the wood, in which the risk of cracks is minimal.
Sometimes situations arise when it is necessary to dry lumber intended for various construction or carpentry work. And if specialized drying chambers are usually used for these purposes, then to prepare a small volume of boards, it is quite possible to get by with alternative methods. However, before drying boards at home, it is advisable to study certain nuances of this process.
Why is wood dried?
Almost any person who has dealt with wood processing knows firsthand that initially all lumber is saturated with natural moisture, and it is very important to take care in advance to remove it from the body of the board. After all, in otherwise, during the operation of a finished product, cracking of the wood material, its warping (deformation) and even fracture may occur. In addition, damp boards are more susceptible to rotting and cannot be used in critical structures.
If we talk about types of wood, then according to the degree of drying they can be divided into the following categories:
- Spruce, cedar, pine (have minimal drying);
- Linden, oak, aspen, ash (belong to varieties with a medium degree of shrinkage);
- Birch, larch, maple (have maximum drying, which is why they can crack).
To make the process easier to understand, it can be noted that soft wood is less susceptible to drying out than its hard counterparts.
Wood drying methods
To obtain wood with specified technical characteristics (in terms of humidity) at home, you can use various methods; we list the main ones.
Air drying lumber
Is the simplest and at the same time effective option wood preparation. Since it does not require significant costs, and the whole process is implemented naturally (gradually). With this method, it is very important to protect the wood during the drying process from direct exposure to ultraviolet radiation (sun rays) and precipitation.
To dry the boards using this method, proceed as follows:
- Clear the area of foreign objects (stones, roots, etc.) and level it.
- Provide waterproofing of the drying area (by laying a layer of roofing material, film or hay).
- Using smooth and strong elements (beams, pipes, rails, logs, etc.) a level base is formed.
- Lumber is stacked on the resulting base in such a way that between adjacent boards there is a gap equal to the thickness of the board (gaskets should be installed in small increments - no more than 1 meter and have the same size, and at the extreme points the gaskets should be placed flush with the ends of the boards). In addition, the minimum distance from the bottom board to the ground must be at least 0.3 meters.
- Slate or similar is placed on the top of the stack roofing material, with such a condition that precipitation does not fall on the wood and can be discharged spontaneously (a slope should be provided). If necessary, protection is also provided on the leeward side in order to minimize the ingress of slanting rain.
- To prevent rotting of lumber, it is recommended to open all the ends of the boards with a protective component: wood glue, lime, paint, drying oil or salt solution.
The drying time using this method is quite long (1 – 3 years) and depends on the conditions created and the type of wood. However, the result of the presented technology is very impressive, because it is under natural conditions that up to 75% of moisture can be removed from wood, with minimal deformation of the material.
Fast drying of lumber
In the case of small-scale carpentry operations, wood drying can be done using an alternative (high-speed) method. To do this, just wrap raw lumber (each board separately) in 5-10 layers of thin paper or newspapers, and wrap plastic film over the resulting cake, in which you can first perform a small perforation.
The board prepared in this way should be placed on a flat base in a warm place (sometimes a window sill is used above the radiator) and as the paper becomes saturated with moisture, it should be completely replaced. Depending on the moisture content of the wood, this procedure must be performed up to 5 – 6 times a day.
In addition, to ensure that the dried boards do not warp, it is recommended to periodically turn them over. Complete drying of wood using this method usually takes 3 to 4 days. However, in order to eliminate the possibility of cracking of the material, it is advisable not to speed up this process. If possible, dry straw or sawdust can be used instead of paper and newspapers, because in this case the absorbent can be replaced much less frequently.
Is boiled wood the key to success?
The second method of home drying of wood is boiling it down. To do this, the boards are placed in a large tank of water and simply boiled in it for 2 – 3 hours. After that, the boiled boards are laid out to cool and remove moisture on a flat surface until completely dry.
Drying on the vine
Standing drying is also an effective method of dealing with moisture and involves the following actions:
- On a tree that is planned to be cut down, a wide belt of bark is removed (in a place as close as possible to the root system);
- Due to the cessation of sap flow, living tree dries gradually (usually the process takes about a year);
- Once the tree is felled, it can almost immediately be used for sawing and carpentry work.
When the tree is felled while still wet, they also resort to tricks to ensure proper drying. And all that is enough for this is to remove 65% of the bark from the trunk and leave it in this position for 15 - 20 days. In this case, moisture will very quickly leave the wood through the remaining crown and leaves. After which the wood can be put to work.
Another common method is when the wood is dried in a utility room (shed, hangar). However, when resorting to the specified drying method, it should be taken into account that this room must have high-quality ventilation and have a stable air temperature (without heating).
In order for the wood drying process to be of the highest quality, it is advisable to adhere to basic recommendations during the work.
Firstly, it is best to harvest lumber in the autumn-winter period, when sap flow stops and the moisture content of the material is lowest.
Secondly, when planning carpentry work, it is necessary to remember that smaller boards are less susceptible to deformation during the drying process, which is why, whenever possible, it is justified to form elements (shelves, floors, stairs, etc.) from small-sized elements.
Thirdly, using hardwood (beech, hornbeam, ash, etc.) it is more justified to use already ready materials, undergone industrial drying. Since drying hardwood lumber is associated with certain difficulties (severe cracking), which can cause excessive amounts of waste.
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Drying methods in the manufacture of profiled timber
Building houses from solid timber has its advantages - such buildings are neat and attractive appearance and are suitable for you if you are aiming to build a house from timber with stage-by-stage financing of installation work.
First, the frame of the house is built from timber (this requires partial financing of the entire house project), and after it shrinks, additional cladding and finishing of the facade are carried out.
An improved version of timber construction is a house made from chamber-drying profiled timber.
That is, timber that has been specially dried and designed in such a way as to prevent moisture from getting into the joints. The shrinkage of such a house is significantly less than when building a house from solid timber with natural moisture.
In addition, profiled timber has all the necessary connecting points, which allows you to build a house from timber much faster than a house with manual fitting of logs during the assembly process.
The profiled timber is supplied ready for installation, so it can be immediately treated with antiseptics and fire retardants, making the process of absorbing liquid faster than with conventional painting.
Due to the fact that the surfaces of the profiled timber are planed to the first class of cleanliness - up to the level of eurolining, such a house is initially very neat and attractive, so when installing it, you can do without additional finishing work.
Profiled timber is an ideal environmentally friendly material, since its production uses only wood without glue (as is the case with laminated veneer lumber), and after the house shrinks with a high density of profile joints, there is no need to caulk the walls. These qualities of the timber also contribute to a tighter fit, and the thickness of the walls is within the range of 150-200mm, which is quite sufficient for our climate zone and allows it to be used in construction timber house There is less material than when installing the same house from rounded logs.
This significantly reduces the price of a house made of timber and makes it more profitable compared to building a house made of laminated veneer lumber.
Let's look at how it is produced timber drying.
Drying timber is a fairly lengthy and labor-intensive process.
The main problem is that due to the considerable thickness of the timber, its surface dries out very quickly, but the inside remains damp. And if the drying time was chosen incorrectly, and the drying itself was not done particularly carefully, you cannot avoid unpleasant consequences in the form of bending of the fibers in the beams, their twisting and longitudinal cracks.
A well-dried timber should have a moisture content of 12-18%. There are several types of drying to achieve this optimal moisture content.
Atmospheric, or natural, drying of timber is the most in a simple way– in this case, individual beams are stacked and kept in the open air or under canopies and stored from 2-3 weeks to several months.
The ends of the timber are covered with glue or lime mortar, which prevents the formation of cracks. However, the size of cracks in beams during atmospheric drying is minimal, and compared to other methods, this is considered the least “traumatic” for wood.
Unfortunately, atmospheric land has a number of significant disadvantages. These include constant changes in weather conditions that are almost impossible to control.
When sunny days are replaced by rainy ones, constant changes in temperature and air humidity occur, and as a result, drying out of the wood often leads to damage to its structure. Among them are material deformations due to internal stress, the formation of small cracks and general shrinkage. In this case, the resulting wood defects can be quite significant, which is why large volumes of timber have to be rejected.
An alternative to natural drying is chamber drying of timber.
Drying wood at home
With this method, the timber is placed in drying chambers, in which, with the help of heating elements (heaters), fans and air ducts, the favorable conditions for it to dry. Modern drying chambers can provide several drying modes and can withstand up to several thousand load cycles. Computer control of the process of chamber drying of timber requires entering the cross-section and type of material being dried, as well as setting its initial and required final moisture content in order to obtain the desired result at the output.
Chamber drying of timber is much more effective than conventional atmospheric drying also because its conditions do not depend on the weather and can be varied. For example, a high-temperature regime, when the temperature in the chamber exceeds 100 C, reduces the time the timber remains in it to 20-30 hours, while natural drying of the same volume of lumber can take many months.
Drying timber can also be done using special high-frequency generators that supply high-frequency current to the wood material.
In this case, the wood in the generator circuit acts as a dielectric in a capacitor, converting electrical energy AC to thermal. As a result, the timber warms up and dries out. This method of drying timber is very effective, but its use is limited, since its use entails significant energy costs.
Heat transfer to the material can be carried out: 1) by a gaseous medium - during drying in air, in combustion products or in hot steam; 2) liquid - when drying in kerosene, Vaseline and others hydrophobic liquids; 3) solid body - in contact with the surface of a hot metal; 4) radiant heat— from special radiators; 5) with electric current passing through wet wood and heating; 6) The high frequency electromagnetic field penetrates the wet wood and heats it.
Depending on different heat supply methods In dry material we will give short description main methods of drying wood used in industry:
In atmospheric drying, moisture from the material is used to evaporate moisture from relatively dry atmospheric air. Wood can be dried on roots, in logs, in forests, in sawmills and in other forms.
Dry the wood at the root (especially larch) when you prepare it for rafting to reduce density and reduce sink loss.
Atmospheric drying of wood in logs, uneven rods, cut parts of the trunk are subjected to almost all examples of the use of these varieties. Drying time is 1-3 years.
Incomplete removal of bark (with perforation, but better for rings, which is safer due to later cracks) significantly speeds up the drying of the logs. A radical means to shorten the roasting time of the fired wood is to split it and place it in a perforated plate, which can explode. Atmospheric drying can be accelerated by blowing air through the fan material.
In many companies, atmospheric drying is the only way to reduce wood moisture content.
When artificial wood sushi (convective thermal winding, conductive, dielectric, etc.), we heated the wet substance (or hot air, hot plates or electricity) to increase the humidity and vapor pressure of the wood to speed up the removal of moisture.
The positive properties of drying are the high density of the process, the possibility of wide regulation to achieve the final moisture content of the wood, minimal errors, the possibility of drying throughout the year, regardless of air, and the destruction of fungal infections and insects in heated wood.
Due to the high speed of such drying, large volumes of wood are required for dry drying. Thus, the technological production process in the company can be more organized.
Convective drying with combustion products is similar to convection drying.
Its features are the preparation and supply of material in the form of a gaseous desiccant for combustion products of solid, liquid or gaseous fuels.
Drying devices for this method are easier to operate and less expensive than devices that use air, which is heated by air heaters.
Convective drying with superheated steam at atmospheric pressure is in principle similar to convective drying of material with heated air (see Fig.
Features of drying boards in the home
1.6). Its characteristics are the important temperature of the drying agent (above 100 °C), the absence of air in the chamber, a more intense drying process, but the superheating power is reduced due to overheating.
Combined drying is usually a combination of atmospheric and convective heat or convective heat and dielectric wood.
Drying in hydrophobic liquids, preferably in a loop cloth, as well as impregnating oils and antiseptics, characterized by retention, has a higher process intensity even at temperatures above 100 ° C.
The disadvantages of this method are, if necessary, to supplement with petroleum jelly, contamination of the dried wood and thus poorer adhesion, greater fire hazard.
When preserved, drying wood in liquid preservatives can be very effective. This method is recommended for drying building elements (bridges, facades) as well as bars, sleepers,
etc., work in atmospheric conditions.
Drying wood (see 1, c) is used on plywood, furniture and in the production of skis (when bending skis). The process is characterized by high intensity.
Radiation heating is used for surface drying of parts or products, such as their coatings, dyeing, etc., and also partially for drying veneers.
Drying using electric current and electromagnetic waves is characterized by the fact that the material is heated simultaneously throughout its entire thickness,
e. diathermically. As a result, thick varieties may win. The disadvantages of such drying are the complexity of the device, high installation and operating costs, radio interference and maintenance hazards.
An interesting method of electric drying in slightly acidified water, into which dehydrated wood is immersed. Electricity, passing through water, is selectively directed towards raw wood, which has greater electrical conductivity than water.
In this case, the wood is heated and dried. Then remove it from the water. When heated, it dries quickly, pouring it onto the surface of the air into the environment.
Dry wood
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Dry wood and too damp wood does not rot.
Proper drying of wood at home
Dry wood is a dielectric. However, its electrical resistance decreases with increasing humidity and temperature. To increase the electrical insulating properties, wood is impregnated with transformer oil, linseed oil, and paraffin.
Dry wood is very capable of absorbing water both when exposed to air and especially when immersed in water.
It is characteristic that the absorption of wood and the evaporation of water due to the anisotropy of wood occurs unevenly in different directions. For example, in the longitudinal direction through the ends of the tree, water is absorbed and evaporates approximately 4 times more than in the radial direction, and 2 times more than in the tangential direction.
Dry wood is much stronger than raw wood, glues and paints better. Models must be durable, maintain precise shape and geometric dimensions.
Therefore, raw wood is not at all suitable for models; When it dries, it warps or cracks. However, excessively dry wood absorbs moisture from the atmosphere to a greater extent, the greater the difference in wood moisture content and environment. Moisture contained in wood cells is called bound.
Dry wood has the ability to absorb moisture from the air.
Wood artificially dried at 70 - 80 absorbs moisture approximately 2% less than wood that has not been artificially dried. Wood dried at temperatures above 100 very slowly absorbs moisture from the air.
Dry spruce wood is light yellow, almost white, mechanically it is not inferior to pine, but due to its low resin content (2-4 times less than pine) it is less resistant in the open air, so spruce is used for less critical structures and temporary structures.
For outdoor structures, rot-resistant spruce wood should be used. It should be taken into account that it is difficult to preserve (impregnate) with oily antiseptics.
Drier wood releases gas too rapidly (at 35 - 45 min.
Since dry wood is not a source of nutrition for fungal formations, the formation of fungi in dry, ventilated rooms and in dry wood is excluded.
The electrical conductivity of dry wood is negligible. This allows wood to be used as an electrical insulating material. Electrical conductivity is used to determine the moisture content of wood.
The electrical conductivity of dry wood is also low.
The electrical conductivity of dry wood is very low, especially when the fibers are directed transversely, so it is a good insulator.
But with humidification, electrical conductivity increases, which serves as the basis for measuring humidity according to this physical property.
The saturation of dry wood with hygroscopic moisture obeys the general laws of interaction of polymers with vapors of low molecular weight liquids.
With very dry wood, with moisture content below optimal, in retorts with external heating, retort setting can occur, when the exothermic reaction quickly spreads to all the wood being recharred.
As a result, the temperature and pressure of vapor gases in the reaction space can quickly rise, which sharply worsens the process conditions.
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How to dry oak wood at home
Further processing of wood requires further high-quality treatment and drying.
Otherwise, the oak wood product may burst and change shape and size.
Methods for drying boards
The best time to harvest wood is in late autumn or even winter to avoid excessive moisture in the slabs.
- Drying on the vine. Preparations for her tree should be in the spring. With the selected tree on its roots, a wide strip of bark should be removed. Thus, access to moisture is blocked and the head begins to dry out. When the wood is completely dry, it can be cut and seen on the slabs.
- Atmospheric drying. This is the most inexpensive and common way to dry wood at home.
How to dry boards in the garage
To protect the boards, you should make a crown on the board to protect them from rain. Place the tree on flat surface. For this purpose, logs, pipes, etc. are taken from the top side of the slab (the distance between the top point of the covering and the floor should not be less than 30 centimeters).
- We must take into account that the natural drying chamber will dry out over several months.
- Drying on a concrete base.
Cement soil absorbs moisture well, so this method is also popular. It consists of placing green wood on a clean, dry concrete surface and turning it several times a day.
- When self-drying a tree, it is important to know that:
- This procedure is best done outdoors and we protect the tree from direct sunlight;
- If wood is dried indoors, it should be well ventilated, but without drafts.
Do not dry near heating appliances.
Quick drying of oak wood
If the tree needs to be dried in a short time, you can use the old method invented by our ancestors: the sheet is wrapped in paper (5 to 15 layers), with polyethylene with holes on top.
The plate is then dried in a warm heater or window rack and turned several times a day.
To completely dry thin plates (up to 3 centimeters) it will take no more than 4 days. The thickness of the plate is dried a little longer.
Gathering and preparing to use materials different types and sizes in the future, you need to know where and how to store it, how to dry it, in what condition, moisture, processing conditions. It is undesirable, for example, to cut a product from a new cut log (if the tree was alive), it is filled with moisture. This can lead to finishing the job at the end until your frustration breaks.
But after the wood is dry, its surface, in order to facilitate the initial rough processing, I advise you to wet it. At the end of the relief or sculpture, only a dry surface is required. It is better suited for mechanical and manual processing, so it is better to stick together and finish (polish, polish).
The process of drying wood consists of regulating the internal humidity of the workpiece with the humidity of the environment in which drying occurs.
When making furniture, wood is dried in drying chambers, where the desired humidity, temperature, air movement, etc. are set and maintained.
etc., and in some cases chemical treatment is also used, and the wood is soaked in phenolic alcohol, which releases water, and then dried (after which the wood vibrates like metal).
There are no such options at home, so the material naturally dries out.
It should be remembered that the amount of moisture in a living tree is constantly changing: in November-December it is less, in July and August it is more.
A medicinal product with visible high humidity should be treated for faster and more uniform drying.
It's easy to do.
Remove a large wooden plow or straight inclined chisel, but not completely, with the ends of the logs of ring bark 10-15 cm wide. The binding ends with a composition impermeable to moisture. It can be: oil paint, glue, varnish, varnish, plasticine. Cover, apply oil paper, newspaper or cellophane. This treatment is carried out to prevent moisture from escaping from the mass of material through the ends of the spill.
The fact is that at the ends of the open areas of wood fibers, through which moisture evaporates more actively than on the side of the log.
If you have a keychain with uneven end pieces, I recommend cutting them at right angles to the axis of the case. Firstly, it is necessary to make it easier to cover the end of the protective layer before drying, and secondly, the so-called area can serve as an additional product for stitching or base, and does not need to be treated as if it were ready.
Keep in mind that donkeys, even when dried properly, will often fall apart.
Such cracks do not always extend along the length of the wood, so place logs and slabs 10-15 cm longer than the required size. After drying before using the material, cracked ends can be seen.
Decide to store the material yourself depending on the conditions in which you live, since drying will occur simultaneously with storage.
If it is a suburb, country or rural area, then use the attic, closet, boiling point, crown, where the sun does not penetrate, rain, where there is no moisture and no skewers. Magazines and boards are placed in lines a short distance apart, dry boxes are placed between them to allow air to circulate freely in the gap between the empty door. If the soil is crushed, then the foundation is better located at a height of 40-50 cm from the brick brick.
It is difficult to store a significant supply of wood and large materials in a city apartment. In this case, use a balcony, loggia, mezzanine, cabinets, some free space under the sofa, closet, etc. Always remember: the tree should be stored away from heating radiators, not on the sunny side, and not in tow.
Well, when the supply of wood can be easily obtained, if necessary, select the most suitable part.
For those who love creativity from natural materials(knots, snowflakes, suvels), it is advisable that supplies are constantly in front of your eyes. I don't recommend removing the bark - it will protect the wood from cracking, so it may be helpful to open the image. Every morning we must see the material, study it carefully and understand what the nature of the hotel will say.
Then one happy day will begin with joy, what kind of work can you carve from this chest. In my house I have been from small to large, almost everywhere, and on the loggia - even in the warehouse. Wait patiently until it is your turn. At this time, as it is said, “ripening”, that is, dryness.
Drying time depends on thickness, type of wood and drying conditions.
If your wood is stored outdoors under cover for a long time, it can be brought indoors over time to dry completely. This is best done after several dry, undesirable days, as the percentage of moisture in the wood increases in wet weather.
Drying at home rarely occurs without cracks - sometimes parts of the workpiece along the grain on two or more parts.
In this case, you can use each half to complete a smaller task, or split the log over the crack and cross it with the whole array, then use it as a separate piece.
Once you start working with the workpiece and make sure it is wet, insert it into a plastic bag for rest periods, expand the size of large plastic envelopes.
After one or two days, the inner surface of the polyethylene is contaminated from moisture leaving the wood, then the bag should be removed, turned inward and placed again on the dry side after the next operation. This type of drying produces positive results, but requires patience.
National masters use different ways protecting wood from cracks. Some of these methods often lead to positive results, although they do not provide complete guarantees.
Proper drying of wood
So, for at least 20-30 days, cover it on all sides with kitchen salt or dry sawdust, which absorbs moisture. The drying process is accelerated and occurs with fewer cracks.
Suveli, we cook hats in salt water! The method is not bad, at the same time it relieves all types of pests.
However, the color of the wood may change for the worse as the dyes dissolve during digestion.
When I work on mahogany portraits, to prevent the front from breaking, cover the fresh areas with wax before breaking.
This keeps moisture away from the exposed inner but untreated layers.
Moving work to another room, such as an exhibition, sometimes causes cracks due to changes in humidity.
If you start cutting any raw material (vase, soup, box), select as much internal volume as possible in one step, wall thickness 1-1.5 cm.
The maximum amount of moisture flows out with the harvested wood mass, and the internal tension is removed. Then place the semi-finished product in a room where it will dry evenly. This could be a dry basement, closet, mezzanine. The plastic bag method is also useful. After 20-30 days (as soon as possible), continue processing.
Sometimes when drying thick logs, to speed up the release of moisture and reduce cracks in the core, the drilled hole has a diameter of 4-5 cm.
Practice has shown that without lime, aspen, poplar with a diameter of 20-30 cm with proper drying, “ripening” without cracks takes 3-5 months. Birch, maple, ash, and oak take longer to dry and almost always have two or three cracks.
The foliage of fruit trees is very difficult to remain intact. 2-3 hours after removal from the roots, cracks appear on them, so immediately after cutting the ends should be covered with a waterproof solution and the chest should be dried in a plastic bag in the manner described in the previous example.
I use some of the above methods, but there are so many parts that I can't follow them. Waste, of course, exists, but the percentage good materials significant, so there is enough work.
I pay special attention to the wood, which is of paramount importance: dry land, I follow and do everything necessary to provide them with the necessary characteristics before using them.
As mentioned, wood that is dried without cracks is rotten, which is very important for the cutter.
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