The Technique of FURNITURE MAKING

True dry rot (Lacrymans merulius)

This is an indoor type, and of all the wood - destroying fungi the most serious as it will attack dry seasoned timber if the conditions are suitable. Initially, the infection needs damp,
badly ventilated surroundings, but once the fungus has taken hold it will carry its own water in wide thread-like hyphae which can penetrate thick brickwork in search of fresh material which it rapidly consumes, leaving the characteristic deeply cleft, cube-like charring, often hardly noticeable under painted surfaces except as local sinkages. In dark conditions the fungus may appear as a white woolly growth, or a smooth fan-shaped grey skin with ragged edges exuding moisture droplets, but if light is present then the typical fruit-bodies will appear. Those who have seen a fully formed fruit-body, sometimes many feet across, with its leprous - grey skin suffused with livid patches of white, yellow and lilac-blue, and peppered with rust - red spores are hardly likely to forget the experience.

Treatment for dry rot must be drastic: all infected woodwork cut away and burnt, infected brickwork and non-wood materials scorched with a blow torch, and treated with an efficient antiseptic. Sound wood in the vicinity should be thoroughly brushed over with either a water soluble preservative such as commercial sodium fluoride (4 per cent), zinc chlorate (5 per cent), applied hot if possible; or one of the commercial solvent-type preservatives recommended for the purpose. Care should be taken with all these chemicals in confined spaces, for although they are not intrinsically dangerous to handle they must necessarily be highly toxic if they are to be effective.

Several other dry rots, notably the cellar fungus (Coniophora cerebella), attack house woodwork, but they require continuous moisture and therefore present no hazard to dry timber.