Plywood is a wood material generated as a result of compression at an elevated temperature of the layer (sheet), timber (veneered) comprised small thickness.
A typical plywood is composed of an odd number of veneers, wherein the angle between the course of the fibers in adjacent layers is about 90 °. The plywood symmetry of the stack is maintained with respect to its center. Commonly used binder is usually amino resins (urea formaldehyde, melamine-urea-formaldehyde, urea-melamine-phenol-formaldehyde) or phenol-formaldehyde.
Methods of refining
The surface of certain types of plywood is covered with phenol or melamine foil, or resins (phenol-formaldehyde - bakelite, and urea-formaldehyde - resin tapping). There are also available surfaces covered with plastic or varnish. The plywood structure can be smooth or fluted.(anti-slidding, covered with phenol foil)
The average density of softwood plywood is 550-650 kg / m3, and plywood 640-780 kg / m3
Types of plywood
Depending on the class of moisture resistance there are distinguished: plywood WBP (MR) for use in dry conditions, a clear weld made with amino resin, and waterproof (WBP) for use in exterior conditions, a weld clear made with urea-melamine-phenol formaldehyde or weld dark made with phenol-formaldehyde resin. On the basis of the looks of the surface five classes of plywood are distinguished: E (best), I, II, III, IV (worst)
Furniture, construction (plating, formwork, scaffolding floors and platforms), automotive (floor, wall), boat building, containers.
TRANSPORTATION AND STORAGE
It is recommended to protect transported and stored plywood against rain and moisture. When transporting the narrow surfaces and corners of the plates should be protected against damage. Store in closed, dry rooms, in a flat position. Plywood of different sizes, different kinds of wood and water resistance should not be stored in the same stack.