Investigation of modern oil paints through a physico-chemical integrated approach. Emblematic cases from Valencia, Spain

The study and the characterisation of modern and contemporary oil paintings is still a challenging issue, in particular considering the significant changes in paint production across the 19th and 20th centuries. This paper presents the results of the first physico-chemical integrated study of the artistic materials used in six paintings from the School of Art and Higher Design of Valencia (Escola d'Art i Superior de Disseny, EASD-Valencia), artworks created between 1871 and 1943 by four famous Valencian artists: Salustiano Asenso Arozarena, Salvador Abril I Blasco, Enrique Navas Escuriet and José Bellver Delmás. A wide range of inorganic and organic compounds was identified through a multi-analytical approach by means of visible reflectance spectroscopy, XRF, μ-Raman, FTIR and GC–MS. The investigation on the binding media suggests the use of commercial paint formulations including mixtures of drying, slow- and non-drying oils and the presence of Gum Arabic as well. Traditional pigments (such as vermillion, earth pigments, lead white) and modern pigments (such as zinc white, cobalt and chromium-based pigments) were identified together with fillers and extenders. Degradation products, in particular zinc and lead soaps having strong conservation implications, were also detected. This work, focusing on the identification of the palettes and the binding media used by the selected artists, aims at providing meaningful data and interesting case studies that are useful beyond the Valencian painters solely. This study provides new insight into the use of 19th–20th century commercial oil paints and the selection of painters' palette and their artistic production techniques. Besides, this work highlights the necessity of a multi-analytical approach to obtain valuable information for documentation and preventive conservation.