From the time the wood is cut down to the time it is processed into furniture or used for other purposes, this process often requires a period of drying and drying to complete. Drying is a processing procedure that wood must go through before it can be used for all purposes.

Wood drying, commonly referred to as wood drying, refers to the process of discharging water by evaporation or boiling vaporization under the action of heat. First, the temperature of the wood is increased, the water in the wood is vaporized, and it moves to the surface of the wood in the form of water and water vapor. Then, under the action of the circulating medium, the water on the surface of the wood leaves the surface of the wood in the form of water vapor. This process is called wood drying.

Wood has a small density and a large strength (high quality coefficient), acid and alkali corrosion resistance, good insulation performance, easy cutting, beautiful texture and color and other excellent properties. A large amount of wood is needed in various parts of the national economy, such as construction, machinery, vehicles, ships, textiles, agricultural tools, furniture, musical instruments, aviation, etc. However, the quality of products made from undried wood cannot be guaranteed, so the wood must be dried.

Wood drying generally refers to the process of allowing the moisture in the wood to be discharged from the tree in the form of vaporization or evaporation. There are many methods for wood drying, which are usually divided into two categories: natural drying and artificial drying.

1. Natural drying

Pile the wood in an open field or ventilated shed, use air as a heat and moisture transfer medium, and use the heat of solar radiation to gradually discharge the moisture in the wood to achieve a certain degree of dryness. This drying method is called natural drying, also called atmospheric drying, or air drying for short.

The degree of drying of air-dried wood is limited by natural conditions and varies with different regions, seasons and tree species. Generally, the moisture content can only be reduced to about 10-20% until it reaches the equilibrium moisture content with the atmosphere, and it cannot be lowered. If a lower final moisture content is required, artificial drying must be carried out.

The advantages of air drying are: no need to build drying facilities with high construction costs, no need for energy such as electricity and steam, simple technology, easy implementation, low drying cost, and can meet the drying requirements of air-dried moisture content, so it is still widely used in production.

The disadvantages of air drying are: drying conditions such as temperature and relative humidity cannot be controlled artificially, the drying time is long, the moisture content cannot be kept low, and the area occupied is large. During the drying period, the wood is easily damaged by fungi and insects, causing discoloration, decay, insect infestation, cracking, deformation and other defects.

In order to overcome the above disadvantages and shorten the air drying time, forced air drying has been developed on the basis of ordinary air drying, that is, artificial forced air circulation is used in air drying. It greatly shortens the air drying cycle, has certain advantages, and has been promoted and applied.

2. Artificial drying

Artificial drying refers to the use of artificial methods to create conditions suitable for wood drying in a certain equipment, such as temperature, relative humidity, air circulation speed, etc., or use other heating and dehumidification methods to make the wood expel moisture under artificial control and dry. Artificial drying can ensure drying quality, shorten drying time, and meet the drying requirements of various uses, and even some special requirements.

Wood drying kiln is the most commonly used artificial drying method. Kiln drying is to place wood in a drying kiln with a special building structure or metal structure, artificially control the temperature, relative humidity and air circulation speed of the drying medium, and mainly use the convective heat transfer of the gas medium to dry the wood. Because the drying kiln is also called a drying room or a drying furnace, kiln drying is also called room drying or furnace drying.

In the field of wood processing, the drying kiln is an important equipment that can effectively remove moisture from wood and improve the quality and stability of wood. However, not all wood is suitable for drying with a drying kiln. Different types of wood have different characteristics and different requirements for drying.

First of all, cork is usually more suitable for drying with a drying kiln. Cork mainly includes pine, fir, cypress, etc. These woods are relatively soft, with straight textures and easy to dissipate moisture. For example, pine has good permeability. In the drying kiln, hot air can pass through the pores of the wood more smoothly, accelerating the evaporation of moisture. Moreover, the drying speed of cork is relatively fast, and it is not easy to have drying defects such as cracking. In the construction, furniture manufacturing and other industries, the cork dried in the kiln is not only dimensionally stable, but also has improved anti-corrosion and insect-proof properties and extended service life.

Some varieties of hardwood are also suitable for drying in the kiln. For example, oak, walnut, etc. These hardwoods are hard, dense, and have good wear resistance and durability. Although it is relatively difficult to dry hardwood, it can be effectively dried by reasonably controlling parameters such as temperature, humidity and air flow rate in the kiln. During the drying process, more careful operation is required to prevent problems such as cracking and deformation of the hardwood. For example, when drying oak, a lower temperature and a slower drying speed should be used to ensure that the moisture inside the wood can be evenly released. The hardwood dried in the kiln has a more uniform color and clearer texture, and can be used in high-end furniture, flooring and other fields.

In addition, some imported wood often needs to be dried in the kiln. With the development of international trade, more and more high-quality imported wood has entered the domestic market. These woods may come from different climate zones and growth environments, and their moisture content and drying characteristics are also different. For example, wood from tropical areas usually has a higher moisture content due to the high humidity of the growing environment, and needs to be dried for a longer time in the drying kiln. Wood from temperate areas may be relatively easier to dry, but it also needs to be dried reasonably according to its specific characteristics.

However, some woods are not suitable for drying with drying kilns. For example, some precious wild protected woods are generally not allowed to be dried on a large scale industrially due to their scarcity and legal protection. In addition, some woods for special purposes, such as wood used to make musical instruments, have very high requirements for drying and require special drying methods. The drying kiln may not be able to meet its delicate drying requirements.

In short, to determine which wood is suitable for drying with a drying kiln, it is necessary to comprehensively consider factors such as the type, characteristics, use, and drying requirements of the wood. In practical applications, the parameters of the drying kiln should be reasonably adjusted according to the characteristics of different woods to ensure that the wood can be effectively dried and improve the quality and use value of the wood.