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.

This review is to be considered part of the development of the MEMORI dosimeter, to evaluate the impact of climate (relative humidity, temperature, illumination, etc., including volatile organic compounds) on moveable objects. In the framework of the MEMORI project, Ghent University was given the task to assess pigment degradation upon acetic acid exposure, and to collect information on pigments' stability. Moreover, to obtain a wider knowledge on the stability of common pigments, the effect of a variety of parameters was reviewed from literature. Discolouration and degradation of pigments significantly alter the legibility of polychrome works of art, so that the development of monitoring methods to ensure the preservation of cultural heritage objects is of primary importance.

Raman spectroscopy is a powerful technique for the characterization of materials and is of valuable use in archaeometrical research in general. Green compounds of natural or synthetic origin are found in many research areas, ranging from mineralogy, to pigment identification, to corrosion studies. However, a detailed and comprehensive database of spectra and references is still missing in the literature. This paper provides both, a literature review and downloadable Raman spectra of reference products, to the researcher dealing with green materials in cultural heritage. Moreover, it tackles nomenclature issues. The collected spectra are discussed in relation to the preliminary/commercial identification of the material itself and to the published data. Practical aspects regarding the laser wavelength selection are also discussed with regards to the comparison to published reference spectra. The range of studied green materials is wide and encompasses Cu containing compounds (natural and synthetic, more or less known as pigments or degradation products, including polymorphs of the same formula), Fe based (green earths and synthetic organic pigments), modern Cr and Co green pigments. This approach is illustrated by analysing a cross section of a green zone of the Early Netherlandish panel painting ‘Ghent Altarpiece’ by the Van Eyck brothers. Copyright © 2016 John Wiley & Sons, Ltd.

Raman spectroscopy and X-ray fluorescence (XRF) analysis are commonly applied to archaeological objects as a fast and nondestructive way to characterize the materials. Here, micro-Raman spectroscopy and chemometrics on handheld XRF results were used to completely characterize beads found during archaeological excavations in the Congo. Metallic objects, organogenic materials, and glass beads were studied. Special attention was paid to the glassy materials, as they seem to be of European production. The matrix family and crystalline phases assemblage, as well as the results from principal components analysis on the elemental data, were used to define groups of beads of similar composition, and therefore probably of similar origin. This research project establishes the feasibility of this approach to archaeological glasses, and can be used to confirm and support the bead typologies used by archaeologists.

The recent discovery of the Sphinx Room, belonging to the Domus Aurea Esquiline wing, thanks to the framework given by the project “Non-destructive analytical studies at Parco Archeologico del Colosseo (Rome, Italy)”, allowed to perform an analytical campaign, both in situ and on micro-fragments. The first aim was to contribute to the overall comprehension of the Domus Aurea complex and to contextualize the newly-discovered room inside this extraordinary imperial architecture by means of an archaeometrical characterisation of the painting materials. The palette, composed of Egyptian blue, green earths, iron- and lead-based red, orange and yellow, calcite, carbon-based black, allowed to compare the Sphinx Room to Corridor 92 and Room 114 of Domus Aurea and to other sites in Rome. Furthermore, the employ of an organic binder in some spots can be put forward based on spectroscopic results, which does not exclude a wider use of the a fresco. Furthermore, a complementary methodological strategy was designed, in order to achieve a complete characterization of the materials. In addition to the well-known combination of portable X-ray fluorescence and portable/laboratory Raman analyses, Infrared Fourier Transform Spectroscopy was used, both in situ (Diffuse Reflectance) and in the lab (Attenuated Total Reflectance). The results confirm the suitability of this approach for the characterization of Roman wall paintings, where both inorganic and organic materials are simultaneously present.

In the framework of the inter‐disciplinary KongoKing project, a set of beads from archaeological excavations in the Democratic Republic of the Congo was analysed by means of a minimally invasive, multi‐analytical approach based on micro‐Raman spectroscopy. The full characterization of the materials, including glassy network, opacifiers and colorizers, was achieved thanks to the combination of data from handheld X‐ray fluorescence, variable pressure scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry, micro‐Fourier transform infrared spectroscopy and pyrolysis coupled to gas chromatography and mass spectrometry. The obtained chemical information was used to fill the existing gap in the chemical study of beads from Western Central Africa. The cobalt‐rich blue beads were found to be of Central European origin, while the copper‐rich turquoise beads were manufactured using distinct copper sources. Cadmium yellow and cadmium red are the colourants responsible for the bright colours of bead types 10 and 12, respectively. The type 12 beads were found to be composed of glass covered with a waxy layer tentatively identified as Japan wax. Prosser‐moulded bead type 9 was coloured by means of a chrome–tin pigment, while a combination of Mn and Fe is responsible for the black colour of the type 47 beads. Cuprite is most likely responsible for the red hue of glass layers from type 14. The dark palm green exterior of the type 17 bead was produced by using a combination of Cu and Fe compounds; iron was the only chromophore detected in the Indian red decoration. Copyright © 2017 John Wiley & Sons, Ltd.

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