Abstract
Medieval wall painting fragments, taken at the medieval Mosque of al-Qarawiyyin in Fez, have been investigated by means of X-ray fluorescence and UV-Vis-NIR diffuse reflectance spectroscopies. The analyses permitted to determine the palette of pigments used by craftsmen of the time. Hematite or red ochre were used to obtain red brown colours, calcite for white, copper-based pigments for blue and blue-grey shades while a mixture of cinnabar, lead-based pigments and hematite was adopted to make red-orange colours. Furthermore, the analysis of mortars (external layer and plaster) on these wall painting samples revealed that they are composed mainly by calcite and sometimes by additional compounds such as quartz and gypsum.
Highlights
In the recent decade, there has been a great interest in the use of non-invasive analytical techniques able to answer specific questions about materials used in handcrafting of ancient artworks, for conservation sciences, archaeological studies and art history goals [1,2,3]
Red-brown and white paintings Only the three red-brown colour samples referenced QAR-05-1074, QAR-201-1246 and QAR-06-329 have been analysed by optical reflectance spectrometry; it was not possible to analyse the other fragments because of their dimensions and their geometrical
These latter bands are attributed to electronic transitions of Fe3+ ions [16,17,18,19]. This is in accordance with the red-brown’s reflectance spectrum first derivative which shows an inflexion point around 585 nm characteristic of iron Fe3+. It seems that red ochre or hematite (α-Fe2O3) had been used to achieve the red-brown colour
Summary
There has been a great interest in the use of non-invasive analytical techniques able to answer specific questions about materials used in handcrafting of ancient artworks, for conservation sciences, archaeological studies and art history goals [1,2,3]. The adopted techniques are X-ray fluorescence and UV-Vis-NIR diffuse reflectance spectroscopies; both are non-invasive, not requiring any material removing from the painting surface. X-ray fluorescence permits elementary analyses identifying chemical elements in inorganic materials [8], while UV-Vis-NIR diffuse reflectance allows structural analyses of pigments [9,10,11,12,13] and colourants with a high degree of probability [14]. The wall painting fragments were collected in the course of a recent excavation in al-Qarawiyyin architectural site. They might originate from two neighbouring houses demolished during the extension of the mosque in 1134, during the Almoravids Dynasty period. Published under licence by IOP Publishing Ltd ongoing database on ancient Moroccan wall paintings from the Roman period (Banasa and Volubilis sites) to the medieval Islamic one
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