Mdf, Plywood

Medium-density fibreboard or MDF, is a derivative of wood. It is the most famous and widespread of the fibreboard family, comprising three distinct categories based on the process used and the density: low (LDF), medium (MDF) and high (HDF). It is ideal for creating semi-gloss and glossy opaque coloured furniture because it has no undulations that could compromise the final result of the product. The raw material used comprises many types of wood, whether round wood, scrap, or processing waste, preferably coniferous, it is usually first debarked, then chipped with the aid of chippers or fragmenters, then selected and checked to eliminate any extraneous traces and any too large and badly chopped pieces. The refining to transform wood fragments into fibre is carried out by grinding in order to break the existing bonds and form a fibre paste, facilitated by dipping in water, with the aid of steam and heat or with chemical treatments based on alkaline substances which weaken the lignin bonds. During its manufacture, certain chemical products can be added in order to provide them with extra features, such as avoiding the appearance of fungus, mould, making it water repellent and fireproof. MDF panels have a uniform colour; unlike pure wood, they have no veins, thus facilitating their processing.
Plywood is a material manufactured from thin layers or “sheets” of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured boards which includes medium-density fibreboard (MDF) and particle board (chipboard). All plywoods bind sheets of resin and wood fibre (cellulose cells are long, strong and thin) to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent in all directions. There is usually an odd number of plies, so that the sheet is balanced – this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it has high stiffness perpendicular to the wood grain direction of the surface. Smaller, thinner, and lower-quality plywoods may only have their plies (layers) arranged at right angles to each other. Some better-quality plywood products will by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axes.