Characterization of Paintings by Laser Ablation-Inductively Coupled Plasma–Mass Spectrometry

Abstract

Nondestructive analytical techniques allow replicate analysis of artwork to be performed without damage. However, these techniques can only provide information about the surface layer of an object. When information regarding the composition of the underlying layers is necessary, a sample must be collected from the artwork. In order to minimize the damage produced, micro-sampling techniques such as laser ablation have been proposed. Laser ablation inductively coupled plasma–mass spectrometry (LA ICP–MS) is a suitable approach but its application to artwork has been focused on metallic, ceramic, and glass objects, with few studies for elemental-stratigraphic analysis of paintings. The objective of this study was to construct a laser ablation ICP–MS system for large artwork without size restriction to evaluate its capabilities for paintings. This study describes a specific optical system and an ablation cell designed for this purpose. The analysis of several paintings of known composition shows that sampling damage is hardly observable in colored layers and that it is less than the damage produced when the samples are taken manually by using a scalpel. The system has a depth resolution from 1 to 2 to 5 to 10 µm, depending on the painting technique, and the information obtained permits discovery of the stratigraphical composition. The ability of LA ICP–MS to determine very thin painting layers in a Renaissance easel painting (favored by the low detection limits of ICP–MS) was also assessed by analyzing a portrait of a member of the Medici Family attributed to Jacopo Pontormo. Results were compared with those obtained by scanning electron microscopy.

Keywords:

• Artwork
• ICP–MS
• Laser ablation
• Paintings
• Pontormo

ACKNOWLEDGMENTS

We are grateful to Ferran Laguarta from the CD6 Center for Sensors, Instruments, and Systems Development, Universitat Politècnica de Catalunya. Additionally, we would also like to express our gratitude to private art collectors, specifically Nadia Hernandez and Manel Riera, Art Conservators.

Notes

*Ablation depth per pulse laser (µm).

*Ablation depth per pulse laser (µm).

*Ablation depth per pulse laser (µm).

*Ablation depth per pulse laser (µm).

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lanl.