Colored grounds of gilt stucco surfaces as analyzed by a combined microscopic, spectroscopic and elemental analytical approach

• Published in: Analytical and bioanalytical chemistry Vol. 397; no. 7; pp. 2667 - 2676
• Main Authors: Sansonetti, A., Striova, J., Biondelli, D., Castellucci, E. M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2010; Springer
• Subjects: Analysis; Analytical Chemistry; Biochemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chromium; Ferric oxide; Food Science; Grounds; Laboratory Medicine; Lead compounds; Mathematical analysis; Monitoring/Environmental Analysis; Original Paper; Raman spectroscopy; Spectroscopic analysis; Spectroscopy; Stucco; Chrome yellow and orange; Gilding technique; Colored grounds; Raman spectroscopy; Mordant gilding
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-010-3491-4

A survey of gilts applied to stucco surfaces that specifically focuses on the compositions of their colored grounds is reported. Gilt samples of a common geographical (Lombardy in Italy) and temporal provenance (17th–18th century) were studied in the form of polished cross-sections by optical and electron microscopy (SEM-EDS), micro-Raman (μRaman) spectroscopy and Fourier-transform infrared microspectroscopy (μFTIR). Comparing samples with superimposed grounds and gilts enabled light to be shed on the choice of specific materials, their stratigraphic functions, decorative effects, and technological performances. Iron oxide pigments were found in the older grounds, sometimes in the presence of lead white (2PbCO 3 ·Pb(OH) 2 ) or minium (Pb 3 O 4 ). In more recent grounds, chrome yellow (PbCrO 4 ), chrome orange (PbCrO 4 ·PbO), cinnabar (α-HgS) and barium white (BaSO 4 ), invariably mixed with lead white, were encountered. Evidence for the use of organic mordants (colophony and wax, or siccative oil) was obtained by μFTIR. This combined μFTIR and μRaman spectroscopic and elemental (SEM-EDS) analytical approach enhances knowledge of the composition of gold grounds, their variability and their chronological evolution.