Localized microwave heating for controlling biodeteriogens on cultural heritage assets

Microwave heating to control biotic agents has already been applied in several fields, in particular in the agri-food and manufacturing industries. We applied localized microwave heating at 2.45 GHz to treat biotic agents infesting wooden artifacts and stone artifacts of interest for the cultural heritage. Compared to conventional techniques and other physical methods microwave heating is safe and pollution-free. In fact, compared to biocides and mechanical removal it has a low-interaction with the material thanks to its selective action. In addition, treatment extension, color-independence, penetration depth are enhanced with respect to treatments via thermal radiation, UV, gamma rays and laser cleaning. Thus localized microwave heating treatments can be an effective alternative for controlling the development of biodeteriogens. Using microwave heating to kill micro-organisms and to prevent microbial deterioration avoids the use of the chemical formulates with biocidal action that are usually applied (before and after cleaning ). The use of chemical products has recently been reviewed the European Union's Biocidal Products in order to limit the risks to the substrate and the operator, to decrease environmental pollution and to prevent the possible selection of microorganisms that are resistant to the most common biocides. We present various applications of localized microwave heating to combat biotic agent growth within wooden artifacts and on the surfaces of stone artifacts. The effectiveness of the method was studied in relation to the characteristics of the microwave system (i.e. the operative conditions, frequency, power, time and temperature of exposure), the type of biological agents infesting the support/material, and the type of support/material itself.