A combined analytical approach applied to Medieval wall paintings from Puglia (Italy): The study of painting techniques and its conservation state

Abstract

A combined analytical approach has been applied to the wall paintings, dated from 10th to 14th centuries, of the Santi Stefani crypt at Vaste (Lecce, Southern Italy). These paintings are a precious testimony of Medieval art in Southern Italy. However, the church shows problems of damp as well as clear evidences of flora, fungi and mold presence, and there is little knowledge of the pictorial methodologies used. Raman spectroscopy allowed to determine the palette and to reconstruct the worksite and the chronological sequence of the various paint layers. Kaolinite, calcite, carbon black, hematite, massicot, goethite, indigo and azurite were identified as pigments along with synthetic pigments, like phthalocyanine blue and chrome yellow. Attenuated total reflectance-Fourier transform infrared spectroscopy suggested the presence of egg as a binder in some pictorial layers. The conservation state of the crypt is poor, and detachments of pigmented layers are frequent because of the presence of subflorescence and efflorescence: nitrate, sulfate and chloride salts have been identified spectroscopically and quantified by ion chromatography. The extensive use of kaolinite in Santi Stefani, actually not uncommon in Medieval art, is observed for the first time in a crypt of Puglia: its use to stabilize some pigments and to improve their adhesion on substrate is proposed.

Characterization of Materials and Artistic Techniques on Two 17th‐Century Neapolitan Wood Sculptures

“…In the upper preparatory layer of the golden areas, the analyses showed the presence of massicot PbO. Its presence was genuine because the characteristic Raman peaks were recorded at 145 and 280 cm À1 and no red shift to 138 and 274 cm À1 (reported when this pigment derived from laser thermal degradation; Fico et al 2016) was observed. Patalano probably used massicot as a catalyst to accelerate the polymerization of the oil used as adhesive of the gold leaf.…”

“…As for the red pigments, vermilion (or cinnabar HgS, having Raman peaks at 253, 284 and 343 cm À1 ; Nastova et al 2012) was the only one employed in the pictorial layers. Hematite Fe 2 O 3 (Raman peaks at 225, 293, 410, 498 and 610 cm À1 ; Fico et al 2016) and red lead (Pb 3 O 4 , Raman peaks at 122, 150, 223, 314, 391 and 550 cm À1 ) were, in fact, identified only in selected preparatory layers. The former was present under the gilded areas (such as in samples 1G and 4G), and it probably had aesthetic purposes, as it gives a warm hue to the gilding.…”

“…Among the instrumental techniques, μ-Raman spectroscopy has proven to be highly efficient, so it is widely used for the identification of constituents of works of art (Bersani et al 2006;De Benedetto et al 2011;Fico et al 2016;Freitas et al 2016;Stanzani et al 2016). Also gas chromatography, combined with mass spectrometry and pyrolysis (Py-GC-MS), is fast, reliable and microdestructive, and permits us to obtain the fingerprint of the organic materials in paint samples (Chiavari et al 2008;Colombini et al 2010;De Benedetto et al 2013).…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Fico and co‐workers presented a combined analytical approach applied to Medieval wall paintings from Puglia, Italy, for which they studied painting techniques and their conservation state. The wall paintings, dated from 10th to 14th centuries of the Santi Stefani crypt at Vaste (Lecce, Southern Italy), are a precious testimony of Medieval art in Southern Italy . Garcia‐Florentino et al investigated the usefulness of portable and Raman imaging to detect decay on mortars from Punta Begon–a Galleries (Getxo, North of Spain).…”

“…The wall paintings, dated from 10th to 14th centuries of the Santi Stefani crypt at Vaste (Lecce, Southern Italy), are a precious testimony of Medieval art in Southern Italy. [120] Garcia-Florentino et al investigated the usefulness of portable and Raman imaging to detect decay on mortars from Punta Begon-a Galleries (Getxo, North of Spain). As a result of Raman, ED-XRF and SEM-EDS imaging, it was possible to map the distribution of the main components through the three mortar layers and also to identify the presence of dolomite {[CaMg(CO 3 ) 2 ]}, which was not possible to detect following single-point micro-Raman analyses.…”