A nondestructive method of identifying pigments on canvas using low frequency electron paramagnetic resonance spectroscopy

ABSTRACT

Electron paramagnetic resonance (EPR) spectroscopy is a useful analytical tool for studying objects with cultural heritage significance. It is generally thought of as a destructive spectroscopy, owing to the small sample size, and thus not used to study paintings. We demonstrate that a form of this spectroscopy known as low frequency EPR spectroscopy can be used to nondestructively identify ultramarine blue, Egyptian blue, Han blue, rhodochrosite, blue vitriol, terracotta red, charcoal, and coal pigments in a linseed oil paint on canvas.

RÉSUMÉ

La spectroscopie de résonance paramagnétique électronique est un outil analytique utile pour étudier des objets à valeur patrimoniale et culturelle. Elle est généralement considérée comme une spectroscopie destructive, en raison de la petite taille de l’échantillon, et donc non employée pour étudier les peintures. Nous démontrons qu’une forme de cette spectroscopie, connue sous le nom de spectroscopie de résonance paramagnétique électronique de basse fréquence, peut être utilisée pour identifier de manière non destructive le bleu outremer, le bleu égyptien, le bleu de Han, la rhodochrosite, le vitriol bleu, la terre cuite rouge, le charbon de bois, et les pigments de charbon d’une peinture à l’huile de lin sur toile. Traduit par Elsa Thyss.

RESUMO

A espectroscopia de ressonância paramagnética eletrônica é uma ferramenta analítica útil para o estudo de objetos significativos para o patrimônio cultural. É geralmente considerada como uma espectroscopia destrutiva, devido ao pequeno tamanho da amostra e, portanto, não é usada para o estudo de pinturas. Demonstramos que uma forma desta espectroscopia conhecida como espectroscopia de ressonância paramagnética eletrônica de baixa frequência pode ser usada para identificar de forma não destrutiva o azul ultramarino, o azul egípcio, o azul de Han, a rodocrosita, o vitríolo azul, o vermelho terracota, o carvão e os pigmentos de carvão em tinta a óleo de linhaça nas telas. Traduzido por Cristina Antunes e Tereza Lança.

RESUMEN

La espectroscopía de resonancia paramagnética de electrones es una herramienta analítica útil para estudiar objetos de importancia en el patrimonio cultural. En general se piensa que es un método de espectroscopia destructiva, debido al tamaño pequeño de la muestra, y por lo tanto no se usa para estudiar pinturas. Demostramos que una forma de esta espectroscopia conocida como espectroscopía de resonancia paramagnética electrónica de baja frecuencia puede utilizarse para identificar no destructivamente el azul ultramarino, el azul egipcio, el azul Han, la rodocrosita, el vitriolo azul, el rojo terracota, el carbón y pigmentos de carbón en una pintura al óleo con aceite de linaza sobre lienzo. Traducido por Amparo Rueda.

KEYWORDS:

• EPR
• electron paramagnetic resonance spectroscopy
• low frequency EPR
• nondestructive and noninvasive testing
• pigment identification
• painting conservation
• transition metal ion and free radical pigments
• surface coil sensing

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Stephany Javier is a graduate student at the Rochester Institute of Technology (RIT) working on her MS degree in Chemistry. She is interested in chemical instrumentation, EPR spectroscopy, and studying objects with cultural heritage significance. She received her BS in Chemical Engineering from Universidad Autónoma de Santo Domingo, Dominican Republic in 2014. She has industrial experience in agronomy as a quality control analyst, pharmaceuticals as a quality control technician, and environmental engineering as an operation engineer leader. Address: Magnetic Resonance Laboratory, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623-5604. Email: [email protected].

Joseph P. Hornak is a professor of Chemistry and Imaging Science at the Rochester Institute of Technology where he directs the activities of the Magnetic Resonance Laboratory and teaches courses in analytical chemistry and magnetic resonance. His research interests include developing LFEPR spectroscopy for studying objects with cultural heritage importance. Dr. Hornak received his Ph.D. in Chemistry from the University of Notre Dame, M.S. in Physical Chemistry from Purdue University, and B.S. in Chemistry from Utica College of Syracuse University. He is author of more than 200 published and conference papers on magnetic resonance related topics. Address: Magnetic Resonance Laboratory, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623-5604. Email: [email protected].

ORCID

Joseph P. Hornak http://orcid.org/0000-0003-1016-9849