When the surface of is in contact with a thin layer of air, the velocity is close to zero, and a stagnant air film separates the air from the surface, which is called the critical layer. Water evaporation can only be achieved by slowly diffusing the air flow into the critical layer. The heat in the airflow can only pass through the critical layer slowly and transfer to the inside of the veneer. In the drying process of Shandong building formwork, the direction of water movement is mainly transverse conduction perpendicular to the fiber arrangement direction, so the resistance is pit resistance, followed by hole resistance and hole wall resistance. The greater evaporation resistance is the critical layer of the veneer surface in contact with air.
The veneer is small in thickness, large in area, and hundreds or even thousands of times longer than the thickness. Therefore, in the drying process of building formwork, moisture is mainly transported through fiber channels. In the water movement of wood, the water in the log can take the cell cavity as the longitudinal channel, and the wood discharged from both ends along the fiber length direction can also pass through the particle holes of the transverse channel on the cell wall. There are many holes on the cell wall, which can be used as the water movement mode along the wall.
