Fourier transform Raman spectroscopic characterization of pigments in the mediaeval frescoes at Convento de la Peregrina, Sahagun, Léon, Spain. Part 1 — preliminary study

The first Raman spectroscopic analysis of coloured frescoes from the thirteenth century Convento de la Peregrina, Sahagun, Léon, Spain is reported. These frescoes were discovered only in 1956 after the church was re-opened after being sealed in the fifteenth century. The pigments were also confirmed by x-ray diffraction analyses. The red pigments are iron(III) oxide (haematite), cinnabar and a mixture of cinnabar and red lead (lead tetraoxide). The discovery of red lead, in particular, is of great interest as historical records recognize the known instability of this pigment mixture in adulterated samples. The black pigment is lamp-black or soot; black particles were also found in some red-pigmented painted areas, which are attributed to contamination from candles or oil-lamps either at the painting stage or during religious services. Copyright © 1999 John Wiley & Sons, Ltd.