The Noninvasive Analysis of Paint Mixtures on Canvas Using an EPR MOUSE

Abstract

Many artists create the variety of colors in their paintings by mixing a small number of primary pigments. Therefore, analytical techniques for studying paintings must be capable of determining the components of mixtures. Electron paramagnetic resonance (EPR) spectroscopy is one of many techniques that can achieve this, however it is invasive. With the recent introduction of the EPR mobile universal surface explorer (MOUSE), EPR is no longer invasive. The EPR MOUSE and a least squares regression algorithm were used to noninvasively identify pairwise mixtures of seven different paramagnetic pigments in paint on canvas. This capability will help art conservators, historians, and restorers to study paintings with EPR spectroscopy.

Mapping Pigments in a Painting with Low Frequency Electron Paramagnetic Resonance Spectroscopy

“…This study is part of a methodical approach to developing LFEPR spectroscopy for noninvasively studying paintings. Earlier studies focused on identifying single pigments [21], mixtures of two pigments [22], pigment layers [22], imaging of one component [23], and now mapping the spatial distribution of four pigments. The presented analytical technique is promising for application in topics related to the preservation of cultural her-itage, since it is non-destructive and the designed system can operate automatically.…”

“…Baker), Han blue (BaOCuO(SiO 2 ) 4 , Kremer Pigments), terracotta red (from fired red clay containing Fe 3+ ), and rhodochrosite (MnCO 3 , Kremer Pigments). as previously described [22]. The painting, Palm Tree on a Beach at Twilight, is of a palm tree growing in sand against a dark blue sky.…”

“…LFEPR has been demonstrated on linseed oil paints with paramagnetic pigments similar to those used in renaissance paintings. Previous studies have focused on identifying pigments in single-component [21] and double-component [22] paint samples, in addition to layered samples [22], on canvas. Another study addressed imaging the spatial distribution of single paramagnetic and ferromagnetic components [23].…”

The Ability of the EPR MOUSE to Study Underpaintings

“…Small samples are removed from a work of art and nondestructively analyzed. Low frequency EPR (LFEPR) spectroscopy and imaging with the EPR mobile universal surface explorer (MOUSE) [19] were recently introduced as viable noninvasive and nondestructive methods for identifying single [20] and mixed [21] paramagnetic pigments on canvas, as well as their spatial distribution in a painting [22]. The EPR MOUSE is inherently well suited for studying underpaintings because it has a depth sensitivity of a few millimeters into a surface.…”

“…The background of LFEPR spectroscopy for cultural heritage studies was presented previously by our group [20,21,27]; therefore, we offer a shorter version of the essentials here and direct the reader to any one of these references for more detail.…”