The Technique of FURNITURE MAKING

Sic materials 1 Woods (hardwoods and softwoods)

WOOD SPECIES

In all, some 43,000 different species of wood - forming plants have been identified, of which some 30,000 could be regarded as timber pro­ducers in some form or other and about 10,000 commercially exploitable. Many of these are of local interest only owing to unsuitability, high cost of logging, non-availability in commercial quantities, etc., but many hundreds remain which are of sufficient importance to merit serious consideration. Certain timber species continually recur, i. e. oak types, walnut types, mahogany types, beech types, etc. whose names are familiar, but in any tropical forest there may be only about 18 timber trees to the acre (0.40 ha) and of these only two or three will be varieties with known names, and the logger must therefore strive to find markets for the remainder in order to make logging a com­mercial proposition. For this reason new species are constantly being introduced into world markets, but large-scale furniture manu­facturers cannot afford to experiment, relying chiefly upon oak, ash, beech, etc., which are always in uninterrupted and plentiful supply, so the newcomers tend to be much cheaper in comparison, although not necessarily inferior in any way.

WOOD CLASSIFICATION

In the classification of plants, including wood, the biological classifications determined by microscopic inspection of the structure are written in Latin, which is the international language adopted, with the genus first (the class or kind of things contained in the particular plant family), then the species (the subordinate kinds within the genus), and lastly the family. Thus European oak will be Quercus (genus), robur (species), family Fagaceae. Within the same family grouping will also be beech, horn­beam, sweet chestnut, etc., but true oaks will always be Quercus although the species will differ, i. e. alba for American white, borealis for

American red and mongolica for Japanese. However, as timber species are usually discovered and put to use long before the botanist arrives to identify them, they will have been given common names arrived at either by adoption of the local or native nickname, the district of source, the port of shipment or some peculiarity of the wood itself.

The precise botanical classification is not of pressing importance to the cabinet-maker (and half an ounce of practical experience with the wood in question is worth a pound of academic knowledge), but it will at least warn him of what to expect. Thus Australian silky oak belongs to the family Proteaceae, and has nothing in common with true oaks (Fagaceae) except a fancied resemblance in the medullary ray structure; while on the other hand both Honduras mahogany {Swietenia macrophylla Meliaceae) and Cuban (Spanish) mahogany {Swietenia mahogani Meliaceae) will have more in common than African mahogany (Khaya grandifolia Meliaceae), sapelewood (Entandro - phragma septentrionale Meliaceae) and guarea {Guarea thompsonii Meliaceae) because in the latter group the genus differs. If, however, the designer or craftsman wishes to pursue his scientific enquiries further, he will usually find that there are classes of instruction in wood technology widely available, and increased knowledge of his material will never be wasted, since for all practical purposes the study of wood does begin at the bench and under the impact of the cutting-tool.

All trees are exogens. increasing their woody fibre by the annual addition of a new layer (annual ring) under the bark, and forming a typical cone-like structure of yearly increments. As producers of structural material they are conveniently grouped within two main classifications:

Softwoods - Coniferous or cone bearing, needle-leafed, usually evergreen, trees that provide the typical commercially-used softwoods.

Hardwoods - Deciduous or broad-leafed trees that comprise the so-called commercially-used hardwoods.

In botanical terms the words 'softwood' or 'hardwood' do not indicate their actual physical hardness or softness. A third classification includes palms and bamboos which are, strictly speaking, giant grasses. There are the inevitable exceptions, of course, for the very soft poplars and willows are broad-leafed and therefore classed as hardwoods, while the harder, needle - leafed larch remains a softwood even though it is deciduous, and yews and hollies are true hardwoods though they are evergreen. However, the classifications are near enough for all practical purposes.