Transparent Drawing Supports and Media Applied On It: Chemical Characterisation and Conservation Problems in Spanish Art Deco Jewellery Design

Abstract

The aim of this study is to characterise the chemical composition of the support materials, binders and pigments used in sales catalogues of Spanish Art Deco jewellery to determine the source of the damage observed in the samples analysed, and to formulate an appropriate conservation method. The difficulty in maintaining these collections in good condition without dismantling them lies, on the one hand, in the use of gouache on a variety of supports not usually used with this aqueous media (nitrocellulose, casein formaldehyde, starched cotton fabric and sulphurised paper), and on the other, in the vulnerability of these materials to agents of deterioration found in archives and libraries. The analysis was performed on a collection of 500 drawings, using the following analytical techniques: optical microscopy, Fourier transform infrared spectroscopy (FTIR), gas chromatography mass spectrometry (GC-MS), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and Raman spectroscopy. The study shows the problems arising from storing some of the before mentioned materials in the same container, and highlights the need to classify each sample by its component materials and not by designer, chronology or type of jewellery.