heritage Article On the Hierarchical Use of Colourants in a 15th Century Book of Hours Angelo Agostino 1 , Eleonora Pellizzi 2 , Maurizio Aceto 3,4, * , Simonetta Castronovo 5 , Giovanna Saroni 6 and Monica Gulmini 1   Citation: Agostino, A.; Pellizzi, E.; Aceto, M.; Castronovo, S.; Saroni, G.; Gulmini, M. On the Hierarchical Use of Colourants in a 15th Century Book of Hours. Heritage 2021, 4, 1786–1806. https://doi.org/10.3390/heritage4030100 Academic Editor: Lucia Burgio Received: 16 July 2021 Accepted: 11 August 2021 Published: 13 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Dipartimento di Chimica, Università degli Studidi Torino, via P. Giuria, 7-10125 Torino, Italy; angelo.agostino@unito.it (A.A.); monica.gulmini@unito.it (M.G.) 2 Laboratoire Scientifique et Technique du Département de la Conservation, Bibliothèque Nationale de France, 14 Avenue Gutenberg, 77607 Bussy Saint-Georges, France; eleonora.pellizzi@bnf.fr 3 Dipartimento di Scienze e Innovazione Tecnologica (DiSIT), Università degli Studi del Piemonte Orientale, viale Teresa Michel, 11-15121 Alessandria, Italy 4 Centro Interdisciplinare per lo Studio e la Conservazione dei Beni Culturali (CenISCo), Università degli Studi del Piemonte Orientale, 11-15121 Alessandria, Italy 5 Museo Civico di Arte Antica, p.zza Castello, 10123 Torino, Italy; simonetta.castronovo@fondazionetorinomusei.it 6 Dipartimento di Studi Storici, Università degli Studi di Torino, via S. Ottavio, 20-10124 Torino, Italy; giovanna.saroni@unito.it * Correspondence: maurizio.aceto@uniupo.it; Tel.: +39-011-360265 Abstract: An illuminated Book of Hours (in use in Chalon-sur-Saône) currently owned by the Museo Civico di Arte Antica and displayed in the prestigious Palazzo Madama in Torino (Italy) was investigated by means of optical microscopy, fibre optic reflectance spectroscopy, fibre optic molecular fluorimetry, X-ray fluorescence spectrometry and Raman spectroscopy. The aim of the scientific survey was to expand the knowledge of the manuscript itself and on the materials and techniques employed by Antoine the Lonhy, the versatile itinerant artist who decorated the book in the 15th century. The focus was to reveal the original colourants and to investigate the pigments used in rough retouches which were visible in some of the miniatures. The investigation was carried out in situ by portable instruments according to a non-invasive analytical sequence previously developed. It was evident that the use of different pigments by the master was ruled, at least partially, by a hierarchical scheme in which more precious materials were linked to the most important characters or details in the painted scene. Keywords: non-invasive techniques; FORS; XRF; illuminated manuscripts; brazilwood; colourants; Antoine de Lonhy; Torino 1. Introduction The identification of the palette is among the various tasks of the scientific examination of an illuminated manuscript. Techniques and materials for illumination are reported, in principle, in some ancient manuals [1,2] which sometimes use colloquial names which may not be reliable descriptors of the substances actually employed. The combined contribution of researchers from the fields of natural sciences and humanities has shed light on this topic and now the set of the most relevant inorganic colourants employed in illumination is known [15]. Nevertheless, the materials used to decorate a specific codex may not be accurately recognised even by an expert eye, since different colourants may yield similar hues, they can be mixed to obtain a particular colour or applied in multilayers and the original colour can be modified and obscured by weathering [6,7]. Therefore, instrumental investigation still plays a crucial role in the recognition of the materials that were actually employed. The characterisation of the palette gives useful information for conservation and also aids the selection of the proper conditions for preserving or exhibiting these fragile Heritage 2021, 4, 1786–1806. https://doi.org/10.3390/heritage4030100 https://www.mdpi.com/journal/heritage