Article

Multianalytical approach to the analysis of English polychromed alabaster sculptures: μRaman, μEDXRF, and FTIR spectroscopies

Department of Analytical Chemistry, University of the Basque Country, P.O. Box. 644, 48080, Bilbao, Spain.
Analytical and Bioanalytical Chemistry (Impact Factor: 3.58). 10/2008; 392(4). DOI: 10.1007/s00216-008-2317-0

ABSTRACT A complete study of several English polychromed alabaster sculptures is presented. The support, pigment, and binders were characterised by combining μEDXRF, μRaman, and FTIR spectroscopies. Among the pigments, minium, vermilion, lead white, carbon black, red iron oxide, and a degraded green copper pigment were determined, together with gold leaf. The presence of the rare mineral moolooite (copper oxalate) was also found as a degradation product in the green areas, where weddellite (calcium oxalate dihydrate) was also determined. These facts, together with degradation of the green copper pigment, suggest microbiological degradation of the original materials. Remains of glue and a varnish were also determined by FTIR spectroscopy and principal-components analysis (PCA) of the spectra. Finally, PCA analysis was carried out to confirm whether the pieces came from the same quarry.

2 Followers
 · 
88 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: La Peña de Candamo Cave, listed as World Heritage by UNESCO in 2008, preserves one of the most important collections of parietal art in the North of Spain and there is an urgent need to evaluate the status of the cave both archaeologically and from the conservation and restoration points of view. In this work, the usefulness of non-invasive mobile instrumentation, such as Raman and EDXRF spectroscopies, is shown when this type of assessments are required under adverse experimental conditions. In addition to the rapid diagnosis that this non-invasive and mobile instrumentation provided, based on the subsequent multivariate analysis of collected spectra, it was possible the identification of the main pigments of the rock art as well as their different origins. Finally, this study also showed the biodeterioration and decalcification processes observed in some areas of the cave and revealed the damage suffered during decades. The effects of such decaying processes over pictorial layers show up the need of a continuous preventive control of paintings in order to minimise further deteriorations.
    Journal of Archaeological Science 02/2013; 40(2):1354–1360. DOI:10.1016/j.jas.2012.10.008 · 2.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Correct identification of pigments and all accompanying phases found in colour layers of historical paintings are relevant for searching their origin and pigment preparation pathways and for specification of their further degradation processes. We successfully applied the analytical route combining non-destructive in situ X-ray fluorescence analyses with subsequent laboratory investigation of micro-samples by optical microscopy, scanning electron microscopy/energy-dispersive spectroscopy and X-ray powder micro-diffraction (micro-XRD) to obtain efficiently all the data relevant for mineralogical interpretations of the copper pigments origin. Cu salts (carbonates, chlorides, sulphates, etc.) used as pigments exist in a range of polymorphs with similar or identical composition. The efficiency of the micro-XRD for direct identification of such crystal phases present in micro-samples of colour layers was demonstrated in the presented paper. A new, until now unpublished, type of copper pigment—cumengeite, Pb21Cu20Cl42(OH)40—used as a blue pigment on a sacral wall painting in the Czech Republic was found by means of micro-XRD. Furthermore, azurite, malachite, paratacamite, atacamite and posnjakite were identified in fragments of colour layers of selected Gothic wall paintings. We found Cu–Zn arsenates indicating the natural origin of azurite and malachite; artificial malachite was distinguishable according to its typical spherulitic crystals. The corrosion of blue azurite to green basic Cu chloride was clearly evidenced on some places exposed to the action of salts and moisture—in a good agreement with the results of laboratory experiments, which also show that oxalic acid accelerates the corrosion of Cu pigments. Figure In situ XRF measurement of Gothic murals in the Benedictine Monastery in Sazava—here The Joseph’s Doubt scene in the capitular hall KeywordsX-ray powder micro-diffraction-Copper pigments-Cumengeite-Wall paintings-Corrosion
    Analytical and Bioanalytical Chemistry 12/2009; 395(7):2037-2050. DOI:10.1007/s00216-009-3144-7 · 3.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This Atomic Spectrometry Update is the first to appear under the new title of “Industrial Analysis.” Changes have been made in the structure of the review to reflect the rapid growth of what is now being conceptualised in the industry as Advanced Materials development. There is a strong synergy between this new field and the Metals and Chemicals areas with which it overlaps, which it is hoped will be evident from this review.
    Journal of Analytical Atomic Spectrometry 01/1989; 7(8). DOI:10.1039/JA989040251R · 3.40 Impact Factor