title: Exploiting external reflection FTIR spectroscopy for the in-situ identification of pigments and binders in illuminated manuscripts. Brochantite and posnjakite as a case study.
abstract: In the present work, the use of portable instrumentation allowing in-situ reflection FTIR analyses is exploited to identify the coloring matters of northern-Italian illuminations dating to the XVI century. In order to build a database of spectra, reference paint samples were prepared spreading the pigments on parchment with two different binders, i.e. gum arabic and egg white, used in antiquity. Pigments for the database were chosen considering their use in the Middle Ages and in the Renaissance and their response in the mid- and near-IR region. The reflection FTIR spectra obtained resulted to be dominated by the specular reflection component, allowing the use of the Kramers-Kronig transform to convert them to the more conventional absorbance FTIR spectra. Several pigments could thus be identified in ancient illuminations, even if some green details showed a spectral pattern different with respect to the most common commercial green pigments of the database. Therefore, in addition, basic copper sulfates brochantite and posnjakite were synthesized and characterized. In three green details, posnjakite was identified, both as a pure compound and together with malachite.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Zaffino
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Guglielmi
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Faraone
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vinaccia
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy. Electronic address: silvia.bruni@unimi.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bruni
mesh_terms: D003116:Color; D019327:Copper Sulfate / Q000032:analysis*; D007558:Italy; D008029:Lighting; D008373:Manuscripts as Topic; D010150:Paint / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D019327:Copper Sulfate
keywords: Basic copper sulfates; Illuminations; In-situ analysis; Pigments; Reflection FTIR