Evaluation of Gypsum and Calcium Oxalates in Deteriorated Mural Paintings by Quantitative FTIR Spectroscopy

Salvadori, Barbara; Errico, Valentina; Mauro, Marcello; Melnik, Elizabeth; Dei, Luigi

doi:10.1081/sl-120026615

Cited by 35 publications

(22 citation statements)

References 5 publications

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“…Oxalate compounds are the main components of human kidney stones [5][6][7] and they are also produced during the degradation of ancient paintings, sculpture, and architectural works [31][32][33][34][35][36] due to both natural and anthropological phenomena, such as climatic conditions and exposure to pollutant agents. Several ancient monuments were found to be covered by a superficial film comprising several compounds such as calcium oxalate, which has protective effects against unfavorable environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Structural, spectroscopic, and thermodynamic characterization of ammonium oxalate monohydrate mineral using theoretical solid-state methods

Colmenero

2019

Journal of Physics and Chemistry of Solids

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In this study, the structural properties, main characteristics of the Raman spectrum, and the thermodynamic properties of the ammonium oxalate monohydrate mineral oxammite, ( 4 ) 2 ( 2 4 ) • 2 , were investigated in theoretical solid-state calculations based on the periodic density functional theory using plane waves and pseudopotentials. The optimized structure of oxammite agreed very well with that obtained from low temperature X-ray diffraction data by structure refinement (orthorhombic symmetry, space group 2 1 2 1 2; lattice parameters: = 8.017 Å; = 10.309 Å; = 3.735 Å). The calculated structural properties, including the lattice parameters, bond lengths and angles, and X-ray powder pattern, accurately reproduced the experimental information. The Raman spectrum determined theoretically agreed with that obtained experimentally. The assignment of the Raman spectral bands significantly improved their previous empirical assignment. Thus, the assignment of a large series of bands was modified and the origins of several previously unassigned bands were found. Five bands in the experimental spectrum at 2344, 2161, 1933, 1902, and 815 −1 , were absent from the computed spectrum and they were identified as combination bands. The band located at 2879 −1 was confirmed as an overtone. Furthermore, the theoretical calculations clearly showed that some features described as single peaks in previous experimental studies were due to the contributions of several bands. The thermodynamic properties of the oxammite mineral, including the specific heats, entropies, enthalpies, and Gibbs free energies, were determined as functions of temperature. The specific heat calculated at 323 K, = 202.3was in good agreement with the corresponding experimental heat capacity, = 211.7where the values only differed by about 4%. Finally, using the computed thermodynamic data, the thermodynamic properties of the formation of oxammite as well as the free energies and reaction constants of the reaction for its thermal decomposition were determined.

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Section: Introductionmentioning

confidence: 99%

Structural, spectroscopic, and thermodynamic characterization of ammonium oxalate monohydrate mineral using theoretical solid-state methods

Colmenero

2019

Journal of Physics and Chemistry of Solids

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“…Regarding the decaying compounds, because the formation of calcium oxalates (whewellite and weddellite) result from the bio-deterioration and/or deterioration of binders in ancient paintings [13,25,26], we tried to weigh up their presence by measuring the FT-IR peak area/μg of sample at 780 cm −1 ( Table 2). Interestingly, the ratio between organic material percentage and the corresponding oxalate area/μg resulted higher in sample S1 and S5 (1.69 and 1.28, respectively) compared to samples S2, S3, and S4 (0.56, 0.45, and 0.54, respectively), thus suggesting that samples S1 and S5 were probably less bio-deteriorated/deteriorated compared to samples S2, S3, and S4.…”

Section: Discussionmentioning

confidence: 99%

An enhanced procedure for the analysis of organic binders in Pompeian’s wall paintings from Insula Occidentalis

et al. 2019

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Quantitation of paint powders of ancient wall paintings is often hindered by the calcite contamination during samples withdrawal. To overcome this problem, a new approach was explored based on the mechanical pulverization of the paint powder followed by the evaluation of its true concentration, namely binders, pigments, and decaying compounds, from the comparison of the calcite FT-IR peak area at 2510 cm −1 with that of the corresponding underlying calcite used as calibrator. After extraction of the pulverized paint powder with polar and nonpolar solvents, liquid chromatography, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry were used to estimate the free amino acids, and fatty acids profiles. Compared to our previous investigation, the results obtained showed a better yield of the extracted organic materials as mg/kg of powder and also a qualitative improvement of the lipids profile.

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“…7 provides evidence of low concentrations of the minerals, gypsum (CaSO 4 •2H 2 O) and goethite (FeOOH) in the Hinder modelling clay. Bands at 603 and 675 cm −1 and at 3553 and 3406 cm −1 superimposed upon the broad O-H stretching band are characteristic of gypsum [19,20]. A small band at 766 cm −1 and a contribution to the broad O-H stretching region indicates goethite is present [21,22].…”

Section: Hinder Artworkmentioning

confidence: 96%

Modelling clay materials used in artworks: an infrared spectroscopic investigation

et al. 2019

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Modelling clays are utilised by artists for their malleable properties. One of the challenges in managing collections containing such materials is the variety of commercial compositions available and, therefore, the variation in the requirements for storage and maintenance of such artefacts. The Art Gallery of New South Wales in Australia is responsible for the care of a range of artworks that contain modelling materials, some of which show detrimental property changes and there is concern for the longevity of such works. The aim of the current research is to determine the compositions of the modelling materials utilised in works produced by different artists in the gallery's collection. Infrared spectroscopy was used to identify the main constituents of samples collected from the works of four different artists and a variety of material types were determined. Oil-based, air-hardening and polymer clays of varying composition were identified in the survey of artworks. Signs of deterioration in particular artworks were able to be characterised using spectroscopy, with the mechanisms identified including loss and oxidation of the oil component. Where a polymer clay was chosen by one artist, the distortion of the artwork was due to flow of the material over time and demonstrates the need for an understanding of the long term properties of the materials being used. The study has highlighted the need for conservators to have a detailed understanding of modelling materials to ensure the longevity of artworks containing this class of materials.

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Evaluation of Gypsum and Calcium Oxalates in Deteriorated Mural Paintings by Quantitative FTIR Spectroscopy

Cited by 35 publications

References 5 publications

Structural, spectroscopic, and thermodynamic characterization of ammonium oxalate monohydrate mineral using theoretical solid-state methods

Structural, spectroscopic, and thermodynamic characterization of ammonium oxalate monohydrate mineral using theoretical solid-state methods

An enhanced procedure for the analysis of organic binders in Pompeian’s wall paintings from Insula Occidentalis

Modelling clay materials used in artworks: an infrared spectroscopic investigation

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