Microwave heating system for controlling biodeteriogens on Cultural Heritage assets

Microwave heating has been used with success in the cultural heritage field to treat the infestation from biotic agents on wood (xilophageous insects), and stone (lichens, black fungi, algae). The damages produced by biodeteriogens are not only aesthetical (e.g. colored patches, patinas, crusts) but can be physical (abrasions, mechanical stress) and/or chemical (solubilization, acidification), eventually resulting in a degradation of the integrity of a monumental surface. The advantages of the microwave approach over conventional techniques (chemical biocides) and other physical methods (UV, gamma rays, laser) are: safety, no pollution, low-interaction with the substrate - with reference to the former - treatment extension, color-independence, penetration depth - with reference to the latter. The critical aspects of the design of applicators/antennas for transferring microwave energy to the material to be treated are faced by a FEM modeling of the coupled electromagnetic/thermal problem. The numerical results obtained in terms of electric field and temperature distributions assist to quantify the efficacy of the microwave treatment needed to control the particular biodeteriogen agent.