Mediaeval cantorals in the Valladolid Biblioteca: FT-Raman spectroscopic study

Raman spectroscopic studies of three mediaeval cantorals in the Biblioteca of the University of Valladolid has revealed information about the pigments used on these large manuscripts. Although executed in a simple colour pale tte, very pure cinnabar was used as the major colourant, offsetting the car bon black of the verses and script. A dark blue colour was achieved using a mixture of azurite (basic copper carbonate) and carbon, whereas a light bl ue colour was azurite alone. A grey colour was achieved using azurite, carb on particles and a calcareous 'limewash'. A yellow pigment, used sparely in the cantorals was ascribed to saffron; unusually, there was no evidence fo r the presence of the yellow mineral pigments orpiment, realgar and massico t. In several regions of the vellum specimens, evidence for biodeterioratio n was observed through the signatures of hydrated calcium oxalate. We repor t for the first time the Raman spectra of pigment in situ on a vellum fragm ent, which also shows evidence of substrate bands; comparison of black and red pigmented regions of vellum specimens has shown the presence of calcium oxalate in the black pigmented script but not in the red pigment regions, which suggests that the cinnabar in the red-pigmented regions acts as a tox ic protectant for the vellum substrate against biological colonisation proc esses.