Characterisation of painting materials from Eritrea rock art sites with non-destructive spectroscopic techniques

Zoppi, Angela; Signorini, Giorgio F.; Lucarelli, F.; Bachechi, Luca

doi:10.1016/s1296-2074(02)01234-7

Cited by 46 publications

(30 citation statements)

References 8 publications

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“…We think that the black pigment in San rock art is amorphous inorganic material (e.g., hydrated manganese oxides) undetectable by XRD analysis; other techniques such as infrared analysis and electron microrprobe can be used for the detection of manganese in pigments. Manganese oxides had been reported in black pigments in the Lascaux caves (Chalmin et al, 2004) and in rock art in Eritrea (Zoppi et al, 2002).…”

Section: Discussion Preparation and Application Of Pigmentsmentioning

confidence: 96%

Minerals provide tints and possible binder/extender in pigments in san rock paintings (South Africa)

2008

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Minerals such as iron oxides and clays provide high tinting strength and improve the adhesive properties of pigments. In this study, we investigated the mineral composition of pigments from samples of San rock art. We used X-ray diffraction and scanning electron microscopy to determine the mineral composition and micromorphology of pigments. Results showed that the major minerals in pigments in San rock art are whewellite, quartz, gypsum, hematite, and various alumino-silicate minerals. The red hue in the pigment is due to hematite; gypsum and clays provide the white coloration, whereas black might be due to amorphous manganese compounds. We believe that whewellite with globular habit was extracted from plant sap (e.g., aloe vera) and added to the pigment, perhaps as binder, extender, or whitener. Whewellite with needle-shaped morphology was present in cracks that developed in pigments and indicated an early stage of deterioration of the rock art. We propose that conservationists should seriously evaluate any change in the environmental conditions at the art site (e.g., removal of vegetation to improve touristic view) because such changes might significantly increase thermal fluctuations in pigments and promote crack formation and hence the decay of the San rock art.

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Section: Discussion Preparation and Application Of Pigmentsmentioning

confidence: 96%

Minerals provide tints and possible binder/extender in pigments in san rock paintings (South Africa)

2008

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“…This hypothesis is consistent with present findings since the peak around 650 cm 1 may be ascribed to the Mn 3 O 4 oxide (hausmannite). 19 Furthermore the observed increase of fluorescence and the decrease of the Raman signal under high laser power can be attributed to the high sensitivity of Mn oxides, in particular, in the powder form, to laser irradiation. These compounds indeed undergo laser-induced thermal transformations owing to their great opacity and hence great thermal absorption.…”

Section: Bluementioning

confidence: 98%

Raman identification of green and blue pigments in Etruscan polychromes on architectural terracotta panels

Bordignon¹,

Postorino²,

Dore³

et al. 2006

J Raman Spectroscopy

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Micro-Raman measurements were performed on two Etruscan polychromes on architectural terracotta panels now on display at the Villa Giulia Etruscan Museum in Rome. These painted panels, dated from 530 to 520 B.C., are of particular interest because of the unusual presence of green and blue layers. Etruscans in the Archaic Age indeed mainly used white, red, and black colours for painted terracotta panels. Raman spectra allowed the analytical identification of green (malachite) and blue (Egyptian blue) pigments employed by Etruscans for this kind of artistic production. This finding provides evidence for a larger use of malachite and Egyptian blue, previously well documented only in Etruscan wall paintings. The use of different pigments to obtain different colour tones has been also observed. Egyptian blue is indeed mixed with malachite to obtain different green tones, and a black pigment seems to have been applied over the Egyptian blue layer to obtain a dark blue tone.

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“…Carbon materials, of mineral, vegetable or animal origin, composed ideally of pure carbon, were largely employed during prehistory [1][2][3][4][5][6][7][8] and were never abandoned by artists and artisans. [9] Carbon-based materials are suitable for both dry and liquid drawing (in the form of graphite, charcoal sticks, black chalk, pastels and inks, respectively [1] ) and have been used as pigments for paintings, [2,5,[10][11][12][13][14][15][16][17][18] for polychrome objects [9,19] and for pottery. [8,20] The continuity of use through time and the worldwide distribution of this kind of materials require the establishment of a welldefined terminology that could be easily used for archaeometrical applications, but that keeps into account the major contributions of geological and industrial research to the study of carbon-based materials, along with the information from artistic literature (treatises [1,21,22] ).…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopy for the investigation of carbon‐based black pigments

Coccato

Jehlička

Moëns

et al. 2015

J Raman Spectroscopy

184

136

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a Raman spectroscopic studies of carbonaceous materials are, until now, mainly devoted to geological and industrial materials. On the other hand, it is known from artistic literature that many varieties of carbon-based black pigments were produced and used in different places and times, and according to the artist's preferences. The ability of Raman spectroscopy to analyse particles down to 1 μm and its non-destructiveness make it an ideal tool for pigments investigation. Anyway, the discrimination among different types of carbon-based black pigments is affected by various aspects, one of which is the lack of reference spectra as well as of specific nomenclature. In this paper, reference materials have been studied by means of Raman spectroscopy to provide reference spectra. All the pigments showed two broad bands of carbon, but sometimes specific excitation conditions were required to record a good quality Raman spectrum. The obtained Raman signatures are discussed, on the basis of the specificities of the pigment (natural or artificial origin; structural implications related to the raw materials used or to production processes; etc.). Therefore, on the basis of the Raman spectra of painting materials, further knowledge can be obtained on the type of carbon-based black pigments in works of art.

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Characterisation of painting materials from Eritrea rock art sites with non-destructive spectroscopic techniques

Cited by 46 publications

References 8 publications

Minerals provide tints and possible binder/extender in pigments in san rock paintings (South Africa)

Minerals provide tints and possible binder/extender in pigments in san rock paintings (South Africa)

Raman identification of green and blue pigments in Etruscan polychromes on architectural terracotta panels

Raman spectroscopy for the investigation of carbon‐based black pigments

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