Portable Raman and XRF analyses of pigments in a 15th-century Mallorcan altarpiece from the Oratorio de Santa Ana in Alcúdia, Spain

Abstract

To identify pigments used in a Mallorcan Gothic painting and to investigate their provenance, portable Raman and X-ray fluorescence spectrometers were used to examine in situ the 15th-century Retablo de la Virgen, san Sebastián y san Bernardino, formerly an altarpiece in the Oratorio de Santa Ana in Alcúdia, Spain. The historical pigments vermilion, ultramarine, lead white, orpiment, and hematite were found in pigmented surface layers of the altarpiece, and the elements gold and iron were detected in the expansive gold-colored background areas of the triptych. Two relatively modern pigments, phthalocyanine green and lithopone, were found in a portion of the first small painting in the predella underneath the triptych suggesting a restoration sometime after the late 1930s. Calcium sulfate, as gypsum or anhydrite, was found in the preparation ground layer, as expected for late medieval Mallorcan panel paintings. Known degradation products, weddellite and possibly whewellite, were found. Anglesite was found in an area with lead white and is likely another degradation product. Although spectral markers indicative of the provenance of the historical pigments were not detected, this work contributes to a greater understanding of the composition of late Gothic Mallorcan altarpieces.