Agnès Le Gac

Spectroscopic characterization of a masterpiece: The Manueline foral charter of Sintra

The foral charter attributed by D. Manuel I of Portugal, in 1514, to the village of Sintra was studied using Energy Dispersive X-ray Fluorescence spectrometry, Raman and Infrared micro-spectroscopies. A complete characterization of the pictorial materials used in the production of this masterpiece allowed the identification of iron gall inks used in the written text; pigments such as malachite, azurite, lead white, cinnabar, yellow ochre, gold, silver and carbon black in the illuminations and letterings; filler and binder used in the production of coloring materials and inks. Gum and calcium carbonate were the most recurrent binder and filler identified in this study. Silvering and gilding were mostly obtained by applying ground silver and gold on parchment.

Spectroscopic Characterization of a Contemporary Indian Miniature Painting

A case study on a contemporary Indian miniature was carried out through the application of different spectroscopic techniques. Painting support, pigments, and dyes were largely characterized by means of energy dispersive x-ray fluorescence and Raman microspectroscopy directly on the artwork. Regarding golden motifs and silvered areas, for which these techniques have not provided enough information, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was used as a complementary technique. The painting support was identified as the Bombyx mori silk. Among the colorant matters, several pigments were identified such as chrome yellow, lithopone, hematite, lamp black, mica-titania pearlescent pigment, and tin-based metallic silver, and dyes such as phthalocyanine blue and the recent synthetic pigment red PR9 naphthol AS. All this materials will provide evidence in the support of the contemporary production of the artwork for future studies.

Multianalytical approach for the authenticity of an eighteenth-century Pascal Taskin harpsichord

This paper surveys a detailed characterization of a prestigious harpsichord brought into fashion in 1782 by Pascal Taskin. The implemented analytical methodology required the use of in situ Energy Dispersive X-Ray Fluorescence (EDXRF) for elemental analysis of the color palette, optical and SEM imaging (SE and BSE modes) for the layered structure identification, Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS) for elemental composition of the inorganic compounds, Fourier Transform Infrared (FTIR) spectroscopy for some binders and THM-GC/MS as well for resinous layers identification. By cross-checking these data with those obtained by digital radiography, it was concluded that a true ravalement of the harpsichord was in fact undertaken and that, among more than five interventions applied to the instrument until the present day, the third one may correspond to the one performed at Pascal Taskins time.

Microscopy and X-Ray Spectroscopy Analyses for Assessment of Gilding and Silvering Techniques of Portuguese Illuminated Manuscripts

The objects of this study are various local charters (cartas de foral, in Portuguese) granted by Dom Manuel I, King of Portugal (1495-1521), which substituted for medieval ones and were intended to achieve an administrative unification. These are luxuriously illuminated manuscripts, and our study aims at obtaining a better understanding of the gilding and silvering techniques applied to the parchments, in which the forais were written, between 1500 and 1520. The combined use of microscopy and X-ray spectroscopy analyses allowed us to identify the vestigial materials used for making the parchments, including products such as salt (NaCl), lime (CaO), pumice stone (SiO2+Al2O3), and chalk (CaCO3). Chalk was employed as a whitening agent to give the parchment its final color and opacity. Shell-gold and shell-silver mixed in with animal glue or gum binding media were directly applied on type 1 and 3 forais, while very thin gold leaves (<1 µm) were applied over lead-based tempera grounds (50-180 µm thick) in type 2 forais. Silver was always employed in its finest form without a further protective layer (thus its recursive state of corrosion), while gold was used in various alloy grades.

Challenging wax-cast figurine serial production unravelled by multi-analytical techniques

Eight complementary techniques were successfully applied to study a pair of very alike eighteenth-century colored wax figurines belonging to the Museu Nacional Machado de Castro, Coimbra (Portugal): examination under visible and ultraviolet light, X-ray radiography (XRR), neutron radiography and tomography (NR and NT), energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), micro-X-ray diffraction (μ-XRD), gas chromatography coupled with mass spectrometry (GC/MS) and micro-confocal Raman spectroscopy (μ-Raman). A careful examination of the two objects provided an insight into their manufacturing and revealed that they were cast from the same molds, although details differ. The main cast material employed was a mixture of beeswax, Venice turpentine, other diterpenoid resins and a very low amount of lipids. The wax used was certainly reclaimed from a metallurgic activity involving lost-wax casting. Each figurine consists of sixteen parts, most of which consist of solid wax. The presence of fillings within the body was unexpected. The elements which remained hollowed played a fundamental role at the assembling stage. A loose wooden tenon helped to keep the head in place and metal rods were used to fasten the base to the main body. Polychromy was carried out in wax, with different pigments and opacifiers. The fabrication of the colored wax from different inorganic/organic wastes is also discussed. Textures were achieved by adding materials. The results gathered offered the unique opportunity to verify aspects inherent to the production of multiple copies in wax casting.