Annelien Deneckere

In situ investigations of vault paintings in the Antwerp cathedral.

X-ray fluorescence spectroscopy (XRF) and Raman spectroscopy have been used to examine 15th century mediaeval and 16th century renaissance vault paintings in the Our Ladys Cathedral (Antwerp, Belgium) in view of their restoration. The use of mobile instruments made it possible to work totally non-destructively. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the pigments. For the 15th century vault painting the pigments lead-tin yellow (Pb(2)SnO(4)), lead white (2PbCO(3)xPb(OH)(2)), vermilion (HgS), massicot (PbO) and azurite (2CuCO(3).Cu(OH)(2)) could be identified. The pigments used for the 16th century vault painting could be identified as red lead (Pb(3)O(4)), hematite (Fe(2)O(3)), lead white (2PbCO(3)xPb(OH)(2)) and azurite (2CuCO(3)xCu(OH)(2)). For both paintings the presence of the strong Raman scatterer calcite (CaCO(3)) resulted in a difficult identification of the pigments by Raman spectroscopy. The presence of gypsum (CaSO(4)x2H(2)O) on the mediaeval vault painting probably indicates that degradation took place.

The use of a multi-method approach to identify the pigments in the 12th century manuscript Liber Floridus

A selection of illuminations of the 12th century manuscript Liber Floridus was analysed with Raman spectroscopy (in situ and laboratory measurements), X-ray fluorescence spectroscopy, UV-fluorescence photography and infrared reflectography (IRR). The aim of this study is to determine the pigments used, in order to search for anachronisms. Using a combination of Raman spectroscopy (molecular information) and X-ray fluorescence spectroscopy (elemental information) following pigments could be identified: ultramarine (Na(8-10)Al(6)Si(6)O(24)S(2-4)), azurite (2CuCO(3)·Cu(OH)(2)), caput mortuum (Fe(2)O(3)), vermilion (HgS), orpiment (As(2)S(3)) and lead white (2PbCO(3)·Pb(OH)(2)). Moreover, two synthetic red pigments, PR4 and PR176, and a degradation product, gypsum (CaSO(4)·2H(2)O), were present in the manuscript. To establish the origin of the modern materials UV-fluorescence photography was used. Infrared reflectography (IRR) was applied to visualise the underdrawing of the investigated folios.

The use of mobile Raman spectroscopy to compare three full-page miniatures from the breviary of Arnold of Egmond

The Breviary of Arnold of Egmond is one of the most wealthily illuminated fifteenth century manuscripts in the Northern Netherlands. The manuscript originally contained a number of full-page miniatures, which were all removed at an unknown date before 1902. The three remaining miniatures studied here, are today part of different collections, but they were brought together for an exhibition. Although several historical and art historical details of this breviary have extensively been studied, no examination of the materials used was undertaken before. Analytical techniques, such as mobile Raman spectroscopy, can be used to characterise and identify these materials in a non-invasive way. This paper presents the results of the in situ Raman analysis of three full-page miniatures of the Breviary of Arnold of Egmond. During this study, different pigments could be identified, such as lead white (2PbCO(3)·Pb(OH)(2)), lead-tin yellow type I (Pb(2)SnO(4)), ultramarine (Na(8-10)Al(6)Si(6)O(24)S(2-4)), massicot (PbO), vermilion (HgS) and red lead (Pb(3)O(4)). Next to identification of the pigments, visual analysis was used to detect differences and similarities between the stylistic elements of the three analysed folios.

Towards the differentiation of non-treated and treated corundum minerals by ion-beam-induced luminescence and other complementary techniques

Differentiation of treated and non-treated gemstones is a chief concern for major jewellery import companies. Low-quality corundum specimens coming from Asia appear to be often treated with heat, BeO or flux in order to enhance their properties as precious minerals. A set of corundum samples, rubies and sapphires from different origins, both treated and non-treated has been analysed at the Centre Européen d’Archéométrie, with ion-beam-induced luminescence (IBIL) and other complementary techniques such as Raman, proton-induced X-ray emission (PIXE), and proton-induced gamma-ray emission (PIGE). IBIL, also known as ionoluminescence, has been used before to detect impurities or defects inside synthetic materials and natural minerals; its use for the discrimination of gemstone simulants or synthetic analogues has been elsewhere discussed (Cavenago-Bignami Moneta, Gemología, Tomo I Piedras preciosas, perlas, corales, marfil. Ediciones Omega, Barcelona, 1991). PIXE has been frequently applied in the archaeometric field for material characterisation and provenance studies of minerals (Hughes, Ruby & sapphire. RWH Publishing, Fallbrook, 1997; Calvo del Castillo et al., Anal Bioanal Chem 387:869–878, 2007; Calligaro et al., NIM-B 189:320–327, 2002) and PIGE complements the elemental analysis by detecting light elements in these materials such as—and lighter than—sodium that cannot be identified with the PIXE technique (Sanchez et al., NIM-B 130:682–686, 1997; Emmett et al., Gems Gemology 39:84–135, 2003). The micro-Raman technique has also been used complementarily to ion beam analysis techniques for mineral characterisation (Novak et al., Appl Surf Sci 231–232:917–920, 2004). The aim of this study is to provide new means for systematic analysis of corundum gemstone-quality mineral, alternative to the traditional gemmologic methods; for this purpose, a Spanish jewellery import company supplied us with a number of natural corundum samples coming from different places (part of them treated as explained above). The PIXE elemental concentrations of the samples showed large quantities of calcium and lead in some cases that can be linked to treatment with fluxes or lead oxide. The plot of the chromium and iron concentration grouped the samples in various aggregates that corresponded to the different types of corundum analysed. Micro-Raman complemented the PIXE analysis corroborating the presence of lead oxides but the use of the PIGE technique was not successful for the detection of beryllium due to the low cross section of the nuclear reaction chosen for its identification. IBIL was capable of distinguishing between treated and non-treated samples of the same type based on the luminescent features of the materials.

Identification of inorganic pigments used in porcelain cards based on fusing Raman and X-ray fluorescence (XRF) data.

Raman spectroscopy and X-ray fluorescence (XRF) spectroscopy are often used as complementary techniques that are well suited for the analysis of art objects because both techniques are fast, sensitive, and noninvasive and measurements can take place in situ. In most of these studies, both techniques are used separately, in the sense that the spectra are evaluated independently and single conclusions are obtained, considering both results. This paper presents a data fusion procedure for Raman and XRF data for the characterization of pigments used in porcelain cards. For the classification of the analyzed points of the porcelain cards principal component analysis (PCA) was used. A first attempt was made to develop a new procedure for the identification of the pigments using a database containing the fused Raman–XRF data of 24 reference pigments. The results show that the classification based on the fused Raman–XRF data is significantly better than the classifications based on the Raman data or the XRF data separately.