6533b824fe1ef96bd12801d0
RESEARCH PRODUCT
X-ray fluorescence investigation of gilded and enamelled silver: The case study of four medieval processional crosses from central Italy
Marco FerrettiC. PoleseClodoaldo Roldán Garcíasubject
Materials scienceGilded enamelled silverMetallurgyX-ray fluorescenceMultilayered materialGildingMineralogyX-ray fluorescencefundamental parameters; gilded enamelled silver; medieval processional cross; multilayered material; x-ray fluorescenceAtomic and Molecular Physics and OpticsAnalytical ChemistryFundamental parametersInstrumentationSpectroscopyMedieval processional crossdescription
Abstract The presence of multilayered structures is common in such cultural artefacts as paintings, corroded metals, objects that underwent a whatever form of surface qualification. One of the most usual and complete ways to investigate such structures is observing a cross section, which requires sampling. There are however situations where at least part of the stratigraphic information can be derived non-destructively: the literature shows that X-ray fluorescence (XRF) has frequently been used, in recent years, for this purpose, with special regard to paintings and gilded metals. Aim of this paper is to further explore the suitability of XRF-based techniques to characterise multilayered structures. This is achieved by introducing improvements, with respect to previous works, in both equipment and data processing. The method, that has been developed for gilded and enamelled silver artefacts, relies on optimum excitation conditions provided for silver and on the relationship existing between the ratio AgKα/AgKβ of its fluorescence lines and the gilding thickness itself. The coating (gilding or enamel) thickness is derived by verifying the condition C Kα,Ag = C Kβ,Ag , where C Kα,Ag and C Kβ,Ag are the mass fractions of silver calculated on the lines AgKα and AgKβ, respectively. The calculations are carried out by PyMCA, a Fundamental Parameters code that implements the analysis of multilayered samples. As a case study we investigated in situ the four processional crosses of Borbona, Sant'Elpidio, Rosciolo and Forcella, made of a wood core with attached gilt and embossed silver sheets and enamelled silver plates. The analyses allowed to distinguish ancient restorations from original parts, to characterise the enamels and find their composition consistent with the dates of manufacturing and, as regards the cross of Rosciolo, to hypothesize the contribution of different “hands” in its manufacturing.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2013-05-01 | Spectrochimica Acta Part B: Atomic Spectroscopy |