Wood based panels (including similar panels from other ligno-cellulosic materials)
Included in this group are:|
(i) Wood-based panels such as:
(a) plywood, particle board and fibreboard (fibre building board). They may be manufactured from wood in the form of solid wood, veneers strands, particles or fibres. Bonding agents and other materials may be added during manufacture to improve certain properties. The bonding agent can be an organic binder, as in plywood and particle board, or it may be inherent, as in some fibreboards. Wood-based panels are usually formed in the presence of heat and/or pressure either as sheets of uniform thickness or as shaped or moulded sheets or blocks;
(b) composite structures of the panel type such as cellular board (plywood of cellular construction), and those in which materials other than wood, (e.g. foamed plastic cores and plastic or metal faces or cores) constitute a small part of the whole material content;
(c) panels with an inorganic binder but in which wood or other ligno-cellulosic material constitutes the most important part of the product by volume (e.g. panels, mineral-bonded, wood particle board). The term refers to panels manufactured in plants and not to floor and wall panels assemblies fabricated in situ.
(ii) Panels of non-wood ligno-cellulosic materials, including agricultural residues such as bagasse, flax shives, jute sticks, straw and hemp, in the form of stalks, particles and fibres used in the manufacture board and fibreboard. In these, the bond may be inherent by synthetic resins. Additives may be applied during to improve certain properties.
Wood based panels may have undergone no further treatment than sanding or process or the application of a simple treatment when used in concrete formwork or as exterior siding (in the case of hardboard). They may, however, have undergone special treatment or transformation at the manufacturing stage or subsequently, such as:
(a) veneering, varnishing, lacquering and other types of surface finishing;
(b) impregnation with fire retardants, water repellents, pesticides, etc.; and/or
(c) mechanical transformation (tonguing or grooving, rabbeting, perforation, etc.).