Do you really understand natural defects in wood? Quality Control and Quality Inspection
Wood defects are various defects that exist in wood and can affect its quality and value in use. This includes natural defects in wood, drying defects, and processing defects.
Wood has many advantages and is often used as a decorative material in decoration, but it also has many defects. The decay, deformation, and knots of wood are collectively referred to as the three major defects of wood.
- Knots: During the growth period of a tree, the base of the living or dead branches that grow inside the trunk is formed by the dead branches or living branches on the trunk where they grow, called knots, also known as wooden knots. According to the texture of the knots and their degree of integration with surrounding wood, they are divided into leaking knots, living knots, dead knots, etc.
(1) The leakage joint has largely damaged its own wooden structure and has penetrated into the interior of the tree trunk, which is connected to the decay inside the tree trunk.
(2) Huojie is closely connected to the surrounding wood, with a hard texture and normal structure. To be precise, knots cannot actually be called defects in wood. They make the wood texture complex and form various patterns, such as spiral, wavy, wrinkled, mountain peak, and bird shaped, bringing unique effects to building decoration and decoration.
(3) Dead knots, partially or completely detached from the surrounding wood, have a hard texture (dead knots), some are soft (loose knots), and some have decayed but have not penetrated the interior of the tree trunk (rotten knots). Dead knots form voids in the board due to detachment. The knots in wood processing can bring difficulties, such as when encountering knots during sawing, the feeding speed should be slowed down, otherwise the serrations will be damaged. Local wood forms diagonal lines due to knots, and the surface of the processed wood is not smooth, prone to burrs or chopping, which affects the aesthetics of decorative wood products. In addition, knots also damage the uniformity of the wood and reduce its strength.
- Discoloration: Discoloration refers to the loss of the original normal color of wood due to chemical or fungal erosion. The artificially dried wood does not affect its strength, but only its surface appearance.
- Decay: Decay refers to the invasion of wood by wood decay fungi, which gradually changes the original structure and color of the wood. This way, the material should not be applied to daily life, as the corroded wood material becomes soft and brittle. Infected by decay fungi, the color and structure of wood undergo changes. In severe cases, the wood becomes soft and fragile, and later turns into dry or wet soft blocks, known as decay. Decay can be divided into two types: external decay and internal decay. (1) External decay, distributed around the periphery of tree trunks, is mostly caused by the infection of fallen or dead trees by decay fungi. (2) Internal decay, distributed within tree trunks, is mostly caused by the infection of standing trees by decay fungi. The initial decay has little effect on the material. In the later stage of decay, it not only changes the decorative properties such as wood color and appearance, but also has a significant impact on the strength and hardness of the wood. Therefore, it is prohibited to use wood with decay in load-bearing structures.
- Insect infestation: Wood is damaged by certain insects to form holes, tunnels, and tunnels. The degree of damage is equivalent to decay. Such wood must be selected. Insect infested and corroded stone materials must be selected during the processing. Wood is a natural substance, and trees are often affected by various external factors during their growth, resulting in abnormal wood tissue structure and defects that are unfavorable for painting. Material changes caused by diseases, insects, and other damage to trees (called parasitic defects) are all natural defects of wood.
