The Technique of FURNITURE MAKING
Durability
Hardness is no criterion of durability even though most, but not all, durable woods are essentially hard and dark in colour, due to the higher content of wood substance and the presence of antiseptic tannins and resins. A notable exception is western red cedar, which is not a true cedar but a very light softwood so impregnated with phenolic-type resins that it is almost impervious to decay.
The question of durability hardly arises in indoor domestic furniture, for all woods are sufficiently durable under controlled conditions. Where, however, continuous moist conditions occur in the presence of free oxygen then the wood is immediately subject to decay in various forms. Beech or elm, for instance, will last for centuries, either as furniture or totally immersed in water or deeply buried in the earth; but if either is laid on wet soil, or only shallowly buried in the upper layers which contain free oxygen, it will speedily rot.
Wood for all work exposed to weathering must, therefore, be chosen carefully for natural durability and resistance to decay. Unfortunately, it cannot be assumed that because a wood is highly resinous it is therefore extremely durable, although it will be more durable than wood with a low resin content. Woods of proven durability include oak, chestnut, yew, teak and greenheart; while if the work is to be painted or otherwise protected then obviously woods of only average durability can be used. Some woods are, however, inclined to repel paint, while others will not absorb sufficient preservative except under pressure, therefore reference should be made to the standard textbooks on wood preservation (see Bibliography).
