Laurionite is an orthorhombic lead chloride hydroxide mineral, PbCl(OH). Its synthetic analogue has been recognised as the ‘lead white’ used in Iranian (III millennium BC) [1] Egyptian cosmetics and later on as a pigment in 13th-to-15th century Japanese paintings, in association with blixite, another lead chloride hydroxide mineral [2]. Alternatively, it has been identified as corrosion product on lead artworks. The most common lead white corresponds to the basic lead carbonate, i.e. the mineral hydrocerussite, both in the oriental and occidental artistic production. Other lead white pigments, such as lead chloride and sulphate, are thought to have been manufactured since the 19th century in Europe [3]. However, more ancient recipes are known where lead white had been produced from sodium chloride, possibly leading to laurionite instead of hydrocerussite. Conversely, the presence of laurionite has been explained as a deterioration product of lead white. Here we report some case studies where laurionite was homogeneously found on white and light yellow painted layers and decorations from the 16th and 17th century: decorations of the Ninfeo and paintings in the Room of the Grotesques, in Palazzo Rivaldi, and some paintings from the sacristy of San Pietro in Vincoli, all in Rome. The micro-sampling allowed the recognition of lead chloride products by different analytical techniques. Under UV light, they exhibited a typical yellow fluorescence, highly similar to oil. When analysed by SEM-EDS, the thin section layer where they had been applied showed specific signals of both lead and chlorine. By FTIR spectroscopy, distinctive signals at 3518 cm-1 (sh) and 913 cm-1 were recorded. The occurrence of laurionite was finally confirmed by X-ray diffraction, its most intense reflections being at 27.1, 22.2 and 35.6°2θ. [1] Vidale et al., 2012, Iran, 50, 27-44 [2] Winter, 1981, Stud. Conserv., 26, 89-101 [3] “The Grove encyclopedia of materials and techniques in art”, Ward Gerald W. R. (ed.), Oxford: Oxford University Press, 2008
The occurrence of lead chloride products as pigments in 16th and 17th century decorations / Conti, Lucia; Sidoti, Giancarlo; Raffaele RUBINO, Angelo; Germinario, Giulia; Botticelli, Michela. - (2021), pp. 9-9. (Intervento presentato al convegno SCIENCE ABC, Science Applications Becoming Culture tenutosi a Department of Environmental Biology, "Sapienza" University, P.le Aldo Moro, 5 - 00185 Rome, Italy).
The occurrence of lead chloride products as pigments in 16th and 17th century decorations
Michela BOTTICELLI
2021
Abstract
Laurionite is an orthorhombic lead chloride hydroxide mineral, PbCl(OH). Its synthetic analogue has been recognised as the ‘lead white’ used in Iranian (III millennium BC) [1] Egyptian cosmetics and later on as a pigment in 13th-to-15th century Japanese paintings, in association with blixite, another lead chloride hydroxide mineral [2]. Alternatively, it has been identified as corrosion product on lead artworks. The most common lead white corresponds to the basic lead carbonate, i.e. the mineral hydrocerussite, both in the oriental and occidental artistic production. Other lead white pigments, such as lead chloride and sulphate, are thought to have been manufactured since the 19th century in Europe [3]. However, more ancient recipes are known where lead white had been produced from sodium chloride, possibly leading to laurionite instead of hydrocerussite. Conversely, the presence of laurionite has been explained as a deterioration product of lead white. Here we report some case studies where laurionite was homogeneously found on white and light yellow painted layers and decorations from the 16th and 17th century: decorations of the Ninfeo and paintings in the Room of the Grotesques, in Palazzo Rivaldi, and some paintings from the sacristy of San Pietro in Vincoli, all in Rome. The micro-sampling allowed the recognition of lead chloride products by different analytical techniques. Under UV light, they exhibited a typical yellow fluorescence, highly similar to oil. When analysed by SEM-EDS, the thin section layer where they had been applied showed specific signals of both lead and chlorine. By FTIR spectroscopy, distinctive signals at 3518 cm-1 (sh) and 913 cm-1 were recorded. The occurrence of laurionite was finally confirmed by X-ray diffraction, its most intense reflections being at 27.1, 22.2 and 35.6°2θ. [1] Vidale et al., 2012, Iran, 50, 27-44 [2] Winter, 1981, Stud. Conserv., 26, 89-101 [3] “The Grove encyclopedia of materials and techniques in art”, Ward Gerald W. R. (ed.), Oxford: Oxford University Press, 2008I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
