Multisensorial Assessment of Laser Effects on Shellac Applied on Wall Paintings

Year: 2021

Authors: Striova J., Fontana R., Barbetti I., Pezzati L., Fedele A., Riminesi C.

Autors Affiliation: National Research Council, INO, Largo E. Fermi 6, Firenze, 50125, Italy; Soprintendenza Archeologia, Belle Arti e Paesaggio per le Province di Pisa e Livorno, Lungarno A. Pacinotti 46, Pisa, 56126, Italy; National Research Council, ISPC, Via Madonna del Piano 10, Firenze, 50019, Italy

Abstract: The assessment of five different laser treatments in the conservation of wall paintings was devised on the basis of the surface temperature monitoring by infrared thermography (IRT), ultraviolet-induced fluorescence-visible (UV-VIS) imaging, and optical coherence tomography (OCT). A series of yttrium-aluminum-garnet (YAG) lasers were tested for removal of shellac layers from wall painting mock-ups. The mock-ups were realized as buon fresco with different mineral based pigments (earths and iron oxide) on a lime-and sand-based mortar. After the carbonatation process, all the samples were treated with shellac (5% in ethanol). The effects of neodymium (Nd):YAG, holmium (Ho):YAG, and erbium (Er):YAG laser sources, in different operative modes, on average temperature of the surface, color, and morphology were inspected with complementary sensors. The results show the necessity to adopt a combined approach in establishing safe laser operating conditions to avoid any undesired effects induced on the artefacts by the laser treatments. We demonstrate, for the first time, the performance of the Ho:YAG laser in the removal of a conservation treatment.

Journal/Review: SENSORS (BASEL)

Volume: 21 (10)      Pages from: 3354-1  to: 3354-15

More Information: This research was funded at INO-CNR on the two internal research projects DFM.AD001.135 Diagnostica ottica non invasiva and DFM.AD006.204 SMAART Sistemi e metodi per analisi di beni artistici.
KeyWords: laser cleaning, shellac coating, wall painting, thermal infrared imaging, Ho:YAG laser
DOI: 10.3390/s21103354