Laser cleaning in the conservation of archaeological artifacts: Polychrome wooden objects from ancient Egypt

Abstract

This work describes some of the main results obtained over the years in the application of different lasers to the cleaning of ancient Egyptian painted wooden objects, with the primary goal of removing superficial blackening and altered synthetic adhesives applied within previous conservation treatments. The project’s following phases entailed a systematic comparison of laser sources commonly used in the cultural heritage field, including Nd:YAG 1064-nm and 532-nm lasers in Q-Switching (QS) and Long Q-Switching (LQS) regimes, both alone and in combination with dry cleaning and solvent mixtures. A multi-analytical campaign, aimed to characterize the objects’ materials and techniques, but also to assess their specific state of preservation and to monitor the cleaning process. Results demonstrate how the target materials, layered on the surfaces, could be removed with high spatial control, well preserving the underlying substrate and without mechanical stress to the treated surfaces.