Micro‐Raman spectroscopy analysis of 16th century Portuguese Ferreirim Masters oil paintings

Abstract

In the present work a set of eight altarpieces of the 16th century (1532-1534), attributed to the Ferreirim Masters (Gregório Lopes, Garcia Fernandes and Cristóvão de Figueiredo), from the Santo António de Ferreirim Monastery (North of Portugal), were analysed by micro-Raman spectroscopy. For this purpose some samples were taken from the paintings to characterise its artist's 'school'. It was found that the preparation was made with chalk and gypsum and the palette composed mainly of lamp black, azurite, lead white (mixed with other pigments), lead-tin yellow type I, goethite (the main constituent of yellow ochre), red lead (as under painting), haematite (the main constituent of red ochre) and vermilion. Indigo was detected in one sample. Some derivatives and degradation products were found mainly in the panels subjected to high temperatures during a fire occurred in 1954: a degradation product from massicot or red lead, lead carbonate (dehydrated derivative of lead white), bassanite and anhydrite (hemi-and dehydrated forms of gypsum). These results are compared with those of previous total reflection X-ray fluorescence spectroscopy (TXRF) analyses.

On the stability of mediaeval inorganic pigments: a literature review of the effect of climate, material selection, biological activity, analysis and conservation treatments

“…Unstable, blackening upon light exposure [1,64] Involved in discolouration [93,245] Whitening [68, 93, Green discolouration [156][157][158] Green discolouration [156][157][158] - [28] - [28] Black …”

“…The PbO formed by laser irradiation can be re-oxidized to minium [142]. A role of Cl − ions is also hypothesized [93,245]. The formation mechanism of black discolouration products [plattnerite (PbO 2 ) and galena (PbS)] was recently investigated: no plattnerite could be detected in artificial ageing tests, while the natural ageing of fresco red lead samples yielded calcite CaCO 3 , minium Pb 3 O 4 , plattnerite PbO 2 , anglesite PbSO 4 and gypsum CaSO 4 ·2H 2 O, with the minium grains being gradually converted to alteration products (plattnerite and anglesite) via a sulphation step followed by solvolytic disproportionation [237,242].…”

“…Both pigments are stable to alkali, but sensitive to H 2 S and sulphides, which causes blackening (PbS) [246]. Whereas other lead containing pigment show fire damage, lead tin yellow type I is detected unaltered [245], but heating above 900 °C causes decomposition of the material [20,246]. They are lightfast, opposite to the other Pb based yellow pigment, massicot (PbO), and stable in oil medium [20,246].…”

The Destructive/Non-Destructive Identification of Enameled Pottery, Glass Artifacts and Associated Pigments—A Brief Overview

“…Many of the above compounds were also used in paintings, frescoes, illuminating manuscripts, etc. e.g., in refs [81,[180][181][182][183][184][185].…”

Calcium sulfate fillers and binders in Portuguese 15 th and 16 th centuries: Ground layers from a family painting workshop — Study by multianalytical spectroscopic techniques

“…The results obtained by μ-XRD showed the presence of the compounds gypsum, anhydrite, bassanite, calcite, dolomite and quartz (Table 2); the presence of bassanite, rarely found in ground layers of the ancient Portuguese studied paintings [11,18,19], may suggest that the initial mixture of calcium sulfate might have been anhydrite and a small amount of bassanite. Part of this last one might have been transformed into gypsum during the hydration process of mixing water or glue, before extending the ground layer.…”