Investigation of microwave as a means of eradicating dry rot attack in buildings
C Kjerulf-Jensen, A P Koch
A microwave-apparatus developed for treatment of building-structures infested by dry rot was tested in the laboratory. The test-conditions simulated treatment of either infested timber or infested brickwork. Sawdust samples, both wet and dry, infested by viable mycelium of Serpula lacrymans were packed in glass-tubes. The tubes were then placed in the middle of either 20 cm thick wooden beams or 35 cm brickwork. The temperature during microwave-treatment was measured both in the tubes using toluene thermometers and in the "construction" using thermo-couples of the copper-constantine-type. The viability after treatment was tested by growth-ability on malt-agar, by ATP-content and by nucleus-staining. The lethal temperature with this specific apparatus was 37-39°C in brickwork and 40-50°C in wood. In comparison with more conventional methods of heat transfer microwaves seem to be more efficient. The variation in temperature within the treated area was undesirably high and in situ treatment above lethal temperature with this specific apparatus would lead to an unacceptably high risk of damage.