Chemical Characterization of Pope Pius VII Ancient Ecclesiastical Vestment by a Multi-Analytical Approach

Abstract

This paper presents a multi-analytical investigation performed for the study of the ecclesiastical vestment, with insignia, of Pope Pius VII, painted from the end of the 18th up to the beginning of the 19th century, made of five clothing elements: chasuble, stole, maniple, chalice veil and purse. The aim of this research was to assess the conservation state of the silk and painted backgrounds; to define the manufacturing technique of the work; to localize, if present, the underdrawing and any retouching; to identify the pigments and, where possible, the binders used. A diagnostic protocol was developed based on preliminary investigations through multiband imaging techniques known as MBI (visible, ultraviolet-induced visible luminescence (UVL), near-infrared reflected (NIR) and infrared reflected false color (IRRFC) photography). The images acquired with MBI techniques ensured a more specific choice of spots to be analyzed directly in situ by non-invasive techniques. In particular, portable digital optical microscopy and X-ray fluorescence (XRF) were performed. Two fragments detached from the chasuble were also analyzed by microFT-IR, microRaman, scanning electron microscopy (SEM-EDS) and gas chromatography/mass spectrometry (GC-MS). Application of the multi-analytical protocol enabled the materials used to be characterized and helped to define the peculiar execution technique used. The presence of an underdrawing made with a carbon pencil was highlighted by MBI. Red lakes, iron-based pigments and copper-based pigments have been identified on the painting palette, applied with arabic gum as a binder.