An interdisciplinary, non-invasive study on ten manuscripts coming from the San Colombano abbey in Bobbio

A group of ten manuscripts datable to the X century A.D. and coming from the S. Colombano abbey in Bobbio (Piacenza, Italy) were analysed with non-invasive techniques to characterise the ancient palette of the abbey scriptorium. All analyses were performed in situ using portable instrumentations. Raman spectroscopy, UVvisible reflectance spectrophotometry and XRF spectrometry were the techniques used. The advantage of using complementary techniques was well demonstrated by the nearly full characterisation of the palette of the manuscripts. Results obtained are interesting from different points of view: first at all, being these manuscripts already studied under the historical and artistic side, chemical analysis can give a strong support to the considerations of art historians; secondly, some conservation emergencies were identified that would need to be addressed, that is changing of minium to black plattnerite and tarnishing of copper, used as a substitute for gold, to a greenish carboxylate, possibly acetate-carbonate. Lastly, the occurrence of ultramarine blue on a manuscript should be seen as one of the first evidences of the use of this precious pigment in Medieval Europe.