Wood
WOODEN SHEETS
Wooden sheets (veneers or simple surface) are thin wooden sheets of 0,5- 1mm thickness, that sometimes reaches 8- 10mm. They are produced whether by rotary cut (unwinding), or by reciprocating (vertical or horizontal) cut or by sawing the log. During unwinding a continuous sheet is produced, which is used for coverings (veneers), as long as or the production of plywood.
The production of the veneers is made with reciprocating cuts of the sheet, so that strips will be created, which are sequentially attached, shaping bigger sheets of desirable dimensions, for the decorative covering of the particleboards, fibreboards and plywood.
The simple wooden sheets are the initial product for the production of plywood.
COMPOUND WOOD PRODUCTS
Compound wood products are superior to the pure ones from many utilitarian perspectives. They show high durability to mechanical stresses, to humidity, to insects and parasites and most of the times much reduced cost. Thus, construction abilities are provided, which wood cannot provide.
The Olympic oval of Richmond could never be constructed by sawings. The construction of a wardrobe or a kitchen from wood, instead of particle board, covered with melamine, would be financially inaccessible. This is the main reason why6 compound wood products have displaced, from the construction and the market, at a big rate, the pure wood products.
The compound wood products are different from wood in two main aspects:
· They have a homogeneous body. It is consisted of shredded or crushed wood, distributed uniformly in the mass and welded. The heterogeneous tissue fibers of wood do not longer exist and they do not determine their qualities. The physiochemical qualities of the wooden mass are lost and replaced by qualities that are artificially regulated.
· The main goal of the production of the compound wood products is the achievement of utilitarian qualities similar and competitive to the qualities of the products of other materials, mostly those of metals’ and synthetic polymers’. This leads to the production of composite raw materials, which are synthetized by wood material, synthetic resins and chemical substances. Their products are on the edge between wood products and chemical industry products. Their qualities, which are related to health and environment, approach and usually exceed, the risk of synthetic polymers while they fend off the harmless qualities of wood (reference).
· The information and update for the qualities and the risk that is connected to the use of compound wood products is absent in Greece. Nor a regulatory framework to protect consumers, or relevant training. There are only some regulations for the protection of workers in the wood sector.
KINDS OF COMPOUND WOOD PRODUCTS
The compound wood products conclude various kind categories: the plywood, the laminated wood, the fibreboards, the particleboards and covering material. The discrimination between particleboards and fibreboards is not always totally defined, as the limits of the size of a really small piece of wood and a big fibre of wood are not defined. This is why the nomenclature is not stable and is also different sometimes in different countries. Thus, the products are usually more known based on their commercial name and not their precise composition.
PLYWOOD
The plywood are products that are constructed by the weld of three (ply) or more (plywood) of wooden sheets together. The directions of the wood fibres of the sequential layers are vertical with each other and the total number of layers is usually odd, so that the fibres of the external surfaces of every sheet will have the same direction and will be similar to a wooden sheet. Between the plywood layers a layer of sawing wood can be mediated.
The kinds and the quality of the wooden sheets are selected based on the use for which the plywood is intended. If the use is decorative (furniture, indoor coverings, etc.), surface wooden sheets of better quality are used, with main criteria the aesthetics and the colour, while for internal layers the selection is based on low cost, as long as the quality of the plywood is not seriously affected. If the use is constructional (dividing walls, floors, formwork, crates, indoor furniture construction, etc.), the main criteria is the mechanical durability and not as much the appearance of the product.
WOODEN SHEETS
Wooden sheets (veneers or simple surface) are thin wooden sheets of 0,5- 1mm thickness, that sometimes reaches 8- 10mm. They are produced whether by rotary cut (unwinding), or by reciprocating (vertical or horizontal) cut or by sawing the log. During unwinding a continuous sheet is produced, which is used for coverings (veneers), as long as or the production of plywood.
The production of the veneers is made with reciprocating cuts of the sheet, so that strips will be created, which are sequentially attached, shaping bigger sheets of desirable dimensions, for the decorative covering of the particleboards, fibreboards and plywood.
The simple wooden sheets are the initial product for the production of plywood.
COMPOUND WOOD PRODUCTS
Compound wood products are superior to the pure ones from many utilitarian perspectives. They show high durability to mechanical stresses, to humidity, to insects and parasites and most of the times much reduced cost. Thus, construction abilities are provided, which wood cannot provide.
The Olympic oval of Richmond could never be constructed by sawings. The construction of a wardrobe or a kitchen from wood, instead of particle board, covered with melamine, would be financially inaccessible. This is the main reason why6 compound wood products have displaced, from the construction and the market, at a big rate, the pure wood products.
The compound wood products are different from wood in two main aspects:
· They have a homogeneous body. It is consisted of shredded or crushed wood, distributed uniformly in the mass and welded. The heterogeneous tissue fibers of wood do not longer exist and they do not determine their qualities. The physiochemical qualities of the wooden mass are lost and replaced by qualities that are artificially regulated.
· The main goal of the production of the compound wood products is the achievement of utilitarian qualities similar and competitive to the qualities of the products of other materials, mostly those of metals’ and synthetic polymers’. This leads to the production of composite raw materials, which are synthetized by wood material, synthetic resins and chemical substances. Their products are on the edge between wood products and chemical industry products. Their qualities, which are related to health and environment, approach and usually exceed, the risk of synthetic polymers while they fend off the harmless qualities of wood (reference).
· The information and update for the qualities and the risk that is connected to the use of compound wood products is absent in Greece. Nor a regulatory framework to protect consumers, or relevant training. There are only some regulations for the protection of workers in the wood sector.
KINDS OF COMPOUND WOOD PRODUCTS
The compound wood products conclude various kind categories: the plywood, the laminated wood, the fibreboards, the particleboards and covering material. The discrimination between particleboards and fibreboards is not always totally defined, as the limits of the size of a really small piece of wood and a big fibre of wood are not defined. This is why the nomenclature is not stable and is also different sometimes in different countries. Thus, the products are usually more known based on their commercial name and not their precise composition.
PLYWOOD
The plywood are products that are constructed by the weld of three (ply) or more (plywood) of wooden sheets together. The directions of the wood fibres of the sequential layers are vertical with each other and the total number of layers is usually odd, so that the fibres of the external surfaces of every sheet will have the same direction and will be similar to a wooden sheet. Between the plywood layers a layer of sawing wood can be mediated.
The kinds and the quality of the wooden sheets are selected based on the use for which the plywood is intended. If the use is decorative (furniture, indoor coverings, etc.), surface wooden sheets of better quality are used, with main criteria the aesthetics and the colour, while for internal layers the selection is based on low cost, as long as the quality of the plywood is not seriously affected. If the use is constructional (dividing walls, floors, formwork, crates, indoor furniture construction, etc.), the main criteria is the mechanical durability and not as much the appearance of the product.