Plywood density
The higher the density of the plywood, the better the quality. Generally larger than wood of the same species. The greater the unit pressure during gluing, the greater the density of the plywood. Because wood is prone to plastic deformation at high temperatures, hot-pressing gluing has a higher compression rate than cold-pressing gluing. As the plywood is made of crisscrossed veneers, its thermal conductivity is lower than that the wood of the same material.
The outermost veneer of plywood is called the surface board, the front surface board is called the front board, the back surface board is called the back board, and the inner veneer is called the core board or middle board.
Plywood thicknesses
Plywood is composed of some thin wood chips, such as 3-ply, 5-ply or multi-ply, and occasionally there are odd numbers. According to the combination of different laminates, the thickness of the plywood is also different. Generally, there are 3mm plywood, 5mm plywood, 9mm plywood, 12mm plywood, 14mm plywood, 18mm plywood etc. Of course, based on special circumstances it will also be other thicknesses.
Some rules in the number of plywood layers:
For every 3mm increase in the thickness of the plywood, the number of layers will increase by 2;
For the plywood of the same thickness, the greater the number of layers, the greater the strength. For example, the strength of 15-layer 18mm plywood is greater than that of 13-layer 18mm plywood;
For the plywood of the same thickness, the more layers, the higher the price. For example, the price of 7-layer 6.5mm plywood is higher than that of 5-layer 6.5mm plywood.