Wood quality, look at these 8 factors!

- Nov 21, 2019-

Solid wood furniture is to point to pure solid wood furniture, point to all material namely is the natural material that did not process again, the furniture that does not use any man-made board to make.

Because there are no two identical trees and two identical materials, each product will have its unique characteristics. The natural characteristics of the wood, such as mineral lines, color and texture changes, needle joints, resin capsules and other natural marks, all make the furniture more beautiful.At the same time, the stand or fall of lumber also is the important factor that decides real wood furniture quality. So what are the factors that affect the quality of wood?

I. external factors

1. The temperature

Temperature is the main factor affecting wood drying rate.As the temperature increases, the water pressure in the wood increases, and the viscosity of liquid free water decreases, which is conducive to promoting the flow and diffusion of water in the wood.The ability of dissolving moisture in copper wire drying medium is improved and the evaporation rate of wood surface water is accelerated.But it is worth noting that if the temperature is too high, the wood will cause cracking and deformation, reduce the mechanical strength, discoloration, should be properly controlled.


2. Humidity

Relative humidity is an important factor affecting wood drying rate.In the case of the same temperature and airflow speed, the higher the relative humidity, the greater the partial pressure of water vapor in the medium, the more difficult the wood surface water evaporation to the medium, the slower the drying speed;When relative humidity is low, surface water evaporates quickly, surface water content decreases, water content gradient increases, water diffusion increases, and drying speed is fast.But the relative humidity is too low, will cause cracking and honeycomb and other dry defects and even increase.

3. Airflow circulation speed

Air circulation velocity is another factor that affects wood drying rate.High-speed airflow can destroy the saturated vapor boundary layer on the wood surface, thus improving the heat and mass transfer conditions between the medium and the wood, and accelerating the drying speed.For hard to dry wood or when the wood moisture content is low, the movement of moisture in the wood determines the drying rate.It is of no practical significance to accelerate the evaporation rate of surface water by increasing the velocity of large medium, but will increase the moisture content gradient and increase the risk of producing drying defects.Therefore, hard to dry materials do not need a large medium cycle speed.

Wood drying

The above three factors are external factors that can be controlled by human beings. Proper control can accelerate the drying speed under the premise of ensuring the drying quality of wood.For example, when drying needle-leaved wood or soft and broad-leaved wood sheet, because the moisture inside the wood moves more easily, the dry ball temperature can be appropriately raised, the humidity of the medium can be lowered, and the flow rate of airflow circulation can be improved to speed up the drying speed.But when dry annatto lumber or thick board, appropriate USES lower temperature, higher humidity and lesser airflow circulation speed, lest produce dry blemish.

II. Internal factors

1. Wood species and structural characteristicsDifferent species of wood have different structures, and the size and number of striated holes as well as the size of micro-holes on the striated holes membrane are very different. Therefore, the degree of water movement along the above path is different, that is, wood species is the main internal cause affecting the drying rate.Due to the fact that there are more fillings in the pipes and striated pores of hardwood (such as acid branch wood) and the diameter of micropores on striated membrane, the drying speed of hardwood is obviously lower than that of hardwood (such as acid branch wood).In the same species, increased density, increased resistance to water flow in large capillaries, extended water diffusion pathways in cell walls, and difficult to dry.


2. Wood thicknessThe conventional drying process of wood can be approximately regarded as the one-dimensional heat and mass transfer process along the direction of wood thickness. As the thickness increases, the heat and mass transfer distance becomes longer, the resistance increases, and the drying speed decreases obviously.

3. Moisture content of woodUnder the fiber saturation point, with the decrease of water content, the transverse diffusion coefficient of the absorbed water decreases, while the diffusion coefficient of water vapor in the cell cavity increases. Due to the small proportion of water vapor diffusion in the cell cavity in the drying process, the lower the water content is, the longer the water diffusion path is, so the lower the water content is, the harder it is to dry.

4. Wood sapwoodThere are more inclusions in hardwood heartwood cells, and most of the veins in conifer heartwood are closed, so heartwood is more difficult to dry than sapwood.5. Wood textureWood ray is beneficial to water conduction. The radial water conduction along the wood is about 15%-20% larger than that along the chord direction. Therefore, the chord cutting board usually dries faster than the radial cutting board.

Wood grain

Although the internal cause cannot be controlled, as long as the drying equipment and technology can be rationally used according to the characteristics of wood, the drying speed can also be improved, which can not only reduce unnecessary losses, but also improve the drying effect on the premise of keeping wood property.

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