We report on tests to remove naturally and artificially aged shellac varnish by laser and traditional chemical cleaning from the substrates of mural paintings. Optical tools were used for the evaluation of cleaning processes, in particular laser microprofilometry to assess the changes in the surface morphology and time-domain confocal optical coherence tomography (OCT) to evaluate varnish thickness. The cleaning assessment was integrated with molecular characterization provided by portable Fourier transform infrared spectroscopy operating in reflectance mode, and colorimetric measurements. This complete analytical approach led to optimized laser-based cleaning tests at 1.9 and 2.6 J/cm<sup>2</sup> in the presence of isopropanol, which ensured controllable and safe partial removal of shellac varnish without alteration to the substrate morphology.
Optical and spectroscopic tools for evaluating Er: YAG laser removal of shellac varnish
Striova Jana;Salvadori Barbara;Fontana Raffaella;Sansonetti Antonio;Barucci Marco;Pampaloni Enrico;Pezzati Luca;Colombini Maria Perla
2015
Abstract
We report on tests to remove naturally and artificially aged shellac varnish by laser and traditional chemical cleaning from the substrates of mural paintings. Optical tools were used for the evaluation of cleaning processes, in particular laser microprofilometry to assess the changes in the surface morphology and time-domain confocal optical coherence tomography (OCT) to evaluate varnish thickness. The cleaning assessment was integrated with molecular characterization provided by portable Fourier transform infrared spectroscopy operating in reflectance mode, and colorimetric measurements. This complete analytical approach led to optimized laser-based cleaning tests at 1.9 and 2.6 J/cm2 in the presence of isopropanol, which ensured controllable and safe partial removal of shellac varnish without alteration to the substrate morphology.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
