Studies of pulsed tea CO2 and Nd:YAG lasers application in the ceramics surface conservation

Abstract

Air pollution results in the deposition of variety of organic and inorganic compounds on the surface of historic monuments. Traditional methods of ceramics cleaning include abrasive treatments, chemical treatments, ultrasound and steam cleaning. Laser cleaning is the most effective and the safest of all of the methods used in the restoration of monuments. Often this is the only way to perform cleaning without damaging the surface. The laser technology, in contrast to the traditional one, does not use of water, caustic solvents, solutions, abrasives or other chemicals; hence after execution of works a minimum amount of waste is produced so that is environmentally suitable. The only wastes generated are the impurities ejected from the surface. Safety spectacles and a face mask are the only necessary protective clothing. The paper presents analysis of lasers potentials in cleaning of archaeological ceramic. Ceramic archaeological sample was exposed by the various combinations of laser wavelengths, energy density (fluency) and number of pulses. Based on the results the morphological and chemical changes on the surface of the ceramic samples could be investigated and the damage threshold could be determined. These are the essential parameters in the use of lasers for cleaning. TEA CO2 (10.6 μm wavelength, pulse duration 100 ns) and Nd:YAG laser (wavelength 1064 nm and 532 nm) have been used for surfaces treatment. The ceramics surface morphology modifications, induced by pulsed lasers, were characterized by scanning electron microscope (SEM), while the composition was examined by energy-dispersive (EDX).