Comparative palette characterization of oil-on-canvas paintings of two well-known 19th-century Colombian artists by confocal Raman spectroscopy

摘要

Confocal micro-Raman spectroscopy has been used for the first time in Colombia to obtain the color palette of two Colombian artists from the 19th century: Jose Maria Espinosa and Epifanio Garay. A new technique to handle and store micro-samples from oil-on-canvas paintings is shown, as well as a technique that allows for direct measurement of the front and back surfaces, and stratigraphic layers of the samples, avoiding the classical embedded resin process, thereby increasing the total area of analysis while decreasing the sample size and preparation time before analysis. Additionally, an optical probe for in situ ( on-site) Raman measurements was developed to non-destructively analyze large paintings. Raman spectroscopic and additional optical microscopic observation resulted in the accurate identification of the artistic technique and the pictorial palette of both artists by using the proposed techniques. Common pigments, such as vermillion, carbon black, Prussian blue, lead white, as well non-common pigment as siderite (used as yellow by Espinosa), were clearly identified. These palettes, so far only ascribed to these two artists, were the basis for the authentication of two oil paintings. Copyright (C) 2016 John Wiley & Sons, Ltd.