The Technique of FURNITURE MAKING

DISEASES AND PESTS

Wood which is deeply buried in the ground or completely submerged in water does not decay, as witness the highly prized black bog oak which has been buried for centuries under layers of wet peat, and the use of timber baulks for
underwater piles and breakwaters. However, where there is free oxygen, living fungi will attack the wood, provided there is moisture present; and although most of these fungi are relatively harmless, causing little more than local staining, two main types of rot actively feed upon the wood substance and eventually destroy it.

White rots

These are usually outdoor types, commonly known as 'wet rots' (rotting logs, fence posts, etc.). They consume both the cellulose and lignin content of the wood, leaving only a white pithy or slimy residue.

Brown rots

These are mainly of the indoor type, but can also occur out of doors. They attack the cellulose content only, leaving the lignin content intact, and are commonly known as 'dry rots', with the wood residue usually brown, spongy, dry and deeply cracked with and across the grain, giving a characteristic charred appearance.

Dote

This is an outdoor type of brown rot known commercially as 'dote' or 'punk'. Living trees are affected, also felled logs full of sap and awaiting sawing, the infection spreading through the heartwood and finally emerging as a bracket-shaped fruit-body on the bark. Incipient dote is easily recognizable, as the wood is peppered with round or oval greyish - white spots which do not appear to affect the mechanical strength to any great extent, but in later stages the wood becomes brown, dry, with spongy white streaks. The fungus cannot exist in the dry state, therefore sound unaffected wood need not be treated. As some harmless fungi cause similar brown staining, doteiness can be tested for by lifting a small splinter of the wood surface with a knife; if dote is present the splinter will break easily with a brash fracture. Fruit woods such as pear, apple, cherry, plum, etc. are particularly susceptible to this form of rot.

It is dote that causes the now much sought after spalted timber. Favoured by wood turners and some furniture-makers, maple, beech and walnut produce the most highly prized markings.