Laser studies of metallic artworks

TL;DR

This paper explores laser and analytical techniques for studying and conserving metallic artworks, including non-destructive analysis of pigments and laser cleaning of Roman coins, revealing compositional changes and corrosion removal.

Contribution

It demonstrates the application of laser and microscopic analytical methods to study and conserve metallic artworks, highlighting new insights into corrosion and material composition.

Findings

Corrosion products were successfully removed from Roman coins.

Increased silver concentration observed after laser cleaning.

Non-destructive analysis identified pigments and binding media.

Abstract

Museum curators and archaeologists use analytical science to provide important information on artworks and objects. For example, scientific techniques provide information on artwork elemental composition, origin and authenticity, and corrosion products, while also finding use in the day-to-day conservation of many historical objects in museums and archaeological sites around the world. In this work two special cases are being discussed. In the first part of our work, physicochemical studies of an icon on a metal substrate were carried out using non-destructive, qualitative analysis of pigments and organic-based binding media, employing various microscopic and analytical techniques, such as Optical Fluorescence Microscopy, XRF, and Gas Chromatography. In the second part of our work, laser cleaning of late Roman coins has been performed using a Q-switched Nd:YAG laser (1064 nm, 6 ns) and a GaAlAs diode laser (780 nm, 90 ps). The corrosion products have been removed, while we observe increased concentrations in Ag, which is the main material of the silvering plating found in late Roman coins.