Interpretation and Cognition of Wood Moisture Content!
When you declassify the knowledge of the declassifier board, you will often hear about “water content”. What is the water content in the end?
What exactly does wood moisture mean?
Data show that the percentage of water quality in wood to wood quality is called water content, which is usually used to describe the change of water content in wood.
The existing state of water in wood can be divided into three categories: free water, absorbent water and bound water according to its combination form and position with wood. The main moisture in wood is free water and absorbent water, and the content of combined water is very little. In daily use, water absorption plays an important role in the performance of wood.
As shown in the figure, the water content of wood cell wall (water absorption) is in a saturated state, while the water content of cell cavity without free water is called fiber saturation point. Usually 30% is the saturation point of wood fiber, but there are slight differences between different wood.
Fiber saturation point is the turning point of wood properties. Under the fiber saturation point, wood cell wall wood fibers absorb water just like compression biscuits, wood expands, water content increases and wood strength decreases; when the fiber saturation point is reached, wood cell and cell gap store water like reservoir, and wood volume and performance basically do not change; conversely, when the fiber saturation point is above, wood volume loses water. When the saturation point is below the fiber saturation point, the wood shrinks and the wood strength increases.
Popularly speaking, in the process of wood drying, the fiber saturation point of wood is controlled at the critical point of 30%, and the hardness of wood is guaranteed.