We have been making boards carefully for 24 years, starting from the moisture content, "stable"!

What is moisture content?

Moisture content of boards: Boards and their products under normal conditions contain a certain amount of moisture. In my country, the percentage of the weight of the water contained in the board to the weight of the board after absolute drying is defined as the moisture content of the board.

The moisture content can be calculated using the weight of the completely dry board as the basis. The calculated value is called the absolute moisture content, abbreviated as moisture content (W, %).

Calculation formula:

W = (Gs - Ggo) / Ggo × 100%

W - absolute water content

Gs - wet plate weight

Ggo - bone dry wood weight

Equilibrium Moisture Content: After a sufficient period of time under certain atmospheric conditions, the moisture content of a board will tend to an equilibrium value, known as the EMC for that environment. When the board's moisture content exceeds the equilibrium moisture content of the environment, the board will shrink due to moisture loss, and expand due to moisture absorption. Therefore, a lower moisture content is not necessarily better.

Wood boards contain moisture before processing. Although they are dried before production, they still contain a certain amount of water. Wood is composed of wood fibers. If it is too dry, it will absorb moisture from the air, while if it is too dry, it will evaporate moisture. Therefore, controlling the moisture content of the board during drying has a significant impact on the quality of the board itself and its products, such as deformation and mildew.

Too high moisture content: causes board deformation and mold

During the drying production process, if the moisture content of the board is not controlled to meet the standard when it leaves the kiln, such as the moisture content is too high, it is easy to be infected by fungi, mold, discoloration and decay during storage and transportation in high temperature weather. It is also easy to be attacked by insects and suffer from moth damage. In addition, during the storage process, the moisture inside the board continues to evaporate, causing shrinkage, deformation and cracking of the board, which seriously affects the quality of the product and the service life of the board.

Too low moisture content: causes board breakage and bulging

If the moisture content of the board is too low, it will directly reduce the bonding strength and other physical and mechanical properties of the board. For example, overdry boards will become brittle, have reduced toughness, and have reduced nail holding power, making them difficult to saw and plan. They are also prone to breakage and edge collapse during processing. In addition, if the moisture content of the board is too low, the board will absorb moisture from the surrounding environment during transportation, transport, and use, causing deformation of the board.

Uniform moisture content: longer service life of the board

Wood panels are made of fibrous lignified tissue, characterized by swelling when wet, shrinking when dry, and anisotropy. Changes in moisture content can cause deformation due to swelling and shrinkage, generating internal stress within the panel. When this stress exceeds the wood's tensile strength, cracks and deformation will occur. Therefore, to prevent cracking and deformation, the panel must be dried. Only by maintaining and stabilizing the moisture content within a certain equilibrium range can deformation and cracking be effectively prevented, extending the panel's service life.

Drying is a crucial step in maintaining a reasonable moisture content in wood. We control the moisture content of the wood substrate from the very beginning and throughout the production process to ensure board quality. From substrate to finished product, each eco-board undergoes at least three drying steps and a curing period of at least seven days to maintain a moisture content between 8% and 10%. This ensures the substrate is fully dried, resisting moisture absorption, expansion, cracking, and deformation. This increases the hardness and plasticity of the board, ensuring product stability, bonding strength, and durability.