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Tropical Timber
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Technology
The figure below diagrams the relationship between various segments of the sawmilling and timber processing industry. In some instances, plywood mills compete for their log supply with sawnwood mills. Sawnwood mills tend to be more flexible, and the logs suited for plywood production normally carry a premium
Source: UNCTAD.
The Feasibility of an International Tropical Plywood Futures Contract.
Geneva: United Nations, 1998.
Note: The diagram refers to veneer used in plywood production.
It does not illustrate the flow of veneer intended to be traded as such.
Generally, the process of timber manufacturing today is the same as hundred years ago, apart from differences in the technology used to convert the raw material into a finished product. The process requires the following steps:
Source: Adapted from Western Wood Products Association, Lumber Basics web site.
The wood-based panels group of products includes four main types of panels: veneer sheets, plywood, particle board, and fibreboard. Veneer sheet and plywood are often referred to as "natural wood panels", mainly characterised by the wood species used; the two other panel types are "reconstituted wood panels" generally manufactured from wood waste.
Veneer sheets are thin sheets of wood of uniform thickness (usually not exceeding 6 mm) that are rotary cut (peeled), sliced or sawn for use in plywood, furniture, etc. Normally, a distinction is made between plywood veneers and decorative veneers. Plywood veneers, used for plywood production, are generally produced by a peeling process from the more common species of wood. Decorative veneers - used mainly in the furniture and wood-panelling industries - are produced by slicing or sometimes by sawing finer highly grained woods.
Plywood is produced from three or more thin sheets of veneer which are joined by an adhesive with the wood grain direction of each layer at right angles to the adjacent one. A distinction is made among lumber core plywood or blockboard (with a core of solid wood or veneers), cellular board (core of cellular construction) and composite plywood (with the core or certain layers made of material other than solid wood or veneers).
Particle board is the trade name for panels manufactured from small pieces of wood or other lingo-cellulosic materials, agglomerated with natural or artificial resins or organic binding substances and pressed together in the form of sheets, blocks, and so on. The most common value added product is melamine-faced chipboard (MFC). Particle board is also frequently overlaid with veneer, or laminates of printed paper, foil, etc. Oriented strand board (OSB) is a type of particle board made of several layers of long-fibre wood particles arranged successively at an angle and glued together, which gives great strength. OSB is challenging structural grade (thick) plywood within the construction industry.
Fibreboard is usually manufactured from woodchips that have
been mechanically defibred or steam-exploded or from other defibred
ligno-cellulosic materials which are bonded together in the form of
panels. Depending on the degree of density, the board is divided into
hardboard (highly compressed, with density exceeding 0.8 g/cm3),
insulating board (density not exceeding 0.5 g/cm3), and medium
density fibreboard (MDF) (density exceeding 0.5 g/cm3 but not exceeding
0.8 g/cm3). MDF is competing with particle board and plywood, mainly
in furniture production.
For a closer look at the production of tropical plywood: UNCTAD. The Feasibility of an International Tropical Plywood Futures Contract. Geneva: United Nations, 1998. View pdf (282 KB)
