Spectroscopic characterisation of crusts interstratified with prehistoric paintings preserved in open‐air rock art shelters

Abstract

In situ micro‐Raman spectroscopy (μ‐RS) of rock art paintings in open‐air rock shelters entails several difficulties: sunlight, wind, dust and crusts that mask Raman signals from the pigments and any other component of the paint recipe. These problems have been considered in the present work. Special attention has been devoted to the presence of crusts. Five rock art sites in the eastern Iberian Peninsula with outstanding difficulties to be analysed by this technique have been the object of this study. In situ energy dispersive X‐ray fluorescence and diffuse reflectance infrared Fourier transform spectroscopy using portable instruments have provided important help. Moreover, microstratigraphic studies by μ‐RS and scanning electronic microscopy combined with energy dispersive X‐ray spectroscopy of micro‐specimens from the painting panels have revealed the distribution of the different components. Dolomite and calcite are dominant minerals in the rock substrata. Whewellite, gypsum, calcite, clay, dolomite, α‐quartz, anatase and haematite have been found on the surface of the painting panels or forming stratified layers in the crusts. Haematite and amorphous carbon have been detected in red and black pictographs, respectively. Copyright © 2014 John Wiley & Sons, Ltd.

Raman microscopy of prehistoric paintings in French megalithic monuments

“…Descriptions of the instruments used for the μ ‐RS, SEM/EDS and XPS studies, as well as the protocol used for micro‐specimen extractions, have been given elsewhere . Specific experimental details of this work are reported here.…”

“…Thereby, the more pigments are found within the megaliths record from such a representative area as Brittany, the deeper impact on the interpretation of the Atlantic façade's symbolic world, and the wider our understanding becomes . Raman spectroscopy with complementary techniques is a powerful tool to identify prehistoric pigments . Hence, it is very motivating to investigate vestiges of pictorial decorations in this fundamental megalithic area for the first time.…”

“…Raman spectra from a large number of points may be obtained in situ with portable micro‐Raman spectroscopy ( μ ‐RS) instruments, thereby avoiding numerous extractions of specimens . Orthostats with possible rests of paintings are usually in tumulus chambers without light and wind, two advantages for in situ μ ‐RS . Possible pictorial materials have been analysed by in situ μ ‐RS.…”

Applications of Raman spectroscopy in art and archaeology

“…In situ investigation of rock art paintings by utilisation of micro‐Raman spectroscopy ( μ ‐RS) can be faced with several problems: sunlight, wind, dust and crusts. These problems were addressed by Hernanz et al . giving a special focus on the presence of crusts.…”

Raman spectroscopic analysis of a belltower commemorative wall decoration

“…From the identification of mineral pigment composition, degradation and substrates in ancient frescoes and wall paintings [6][7][8][9][10] and in polychrome statuary [11] to the discovery and evaluation of biological degradation in organic dyes [12,13], textiles [14,15], endangered rock art exposed to hostile environments [16][17][18][19][20] and on the pigments on historiated manuscripts and parchments [21][22][23][24][25][26][27][28][29][30][31][32][33][34] much novel information has been revealed at both a microscopic and macroscopic level of molecular interrogation. In particular, for manuscript pigment analysis and characterisation, a combination of Raman spectroscopic and other microanalytical techniques is found to be extremely useful.…”