A portable microwave system for woodworm disinfestation of artistic painted boards

Microwave power can be effectively used for disinfesting wooden objects of woodworms. Disinfestation is achieved by heating woodworms inside wood above their lethal temperature values. A prototype of a portable microwave system suitable for treating small and delicate wooden objects is described. The system, working at 2.45 GHz, used a commercial magnetron, a radiative applicator, and a non-contacting thermometer to monitor the temperature of the painted surface. A flow of air is blown through the applicator to cool the irradiated surface. A treatment bench has been set up to heat painted boards in controlled conditions. The applicator is placed on the rear side of the board, while the painted side is monitored by means of an infrared thermometer to maintain its temperature below safe levels (e.g. 50-55°C). Results concerning the effect of microwave heating on several specimens infested by woodworms in all metamorphical stages (egg, pupa and larva) are reported and discussed. Preliminary results about possible detrimental effects induced by heating on wooden boards and on painted surfaces are also reported. An experimental procedure for determining the SAR distribution produced by the applicator of the dis infestation system on a wooden board is described. The procedure is based on a thermographic analysis of the heated object. An analysis of the SAR uncertainty due to thermal diffusion and to surface radiation and convection losses is carried out, showing advantages and limitations of the thermographic method.