| 1. |
- Angelin, Eva Mariasole, et al.
(författare)
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The multi-analytical in situ analysis of cadmium-based pigments in plastics
- 2020
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Ingår i: Microchemical Journal. - : Elsevier BV. - 0026-265X. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 Elsevier B.V. Colorants are present in trace concentration in objects made of plastic and their identification is a methodological and analytical challenge. In conservation, the identification of colorants may allow a better understanding of colorant degradation (such as color change and fading) and provide information about the historical development, production and processing of plastics. Although micro-destructive analytical protocols are well established for the analysis of colorants, in cultural heritage, where in situ methodologies are preferred and, in some cases, mandatory, new approaches are greatly needed. In this work, an in situ multi-analytical approach is used to specifically study inorganic cadmium-based pigments that were commonly used for coloring plastics during the 20th c. First introduced as vivid artists’ pigments, cadmium-based additives were used for coloring plastics because of their exceptional performance properties. Eighteen colored polymethyl methacrylate (PMMA) samples, produced in the second half of the 20th c. by the company Plásticos do Sado (Portugal), were studied with a combination of optical microscopy, colorimetry, UV–Vis-NIR diffuse reflectance, laser-induced photoluminescence, vibrational (µ-Raman) and elemental (µ-EDXRF) spectroscopies. On the basis of complementary data, the chemical composition of most of the coloring agents employed in the acrylic samples were identified without any micro-sampling.
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| 2. |
- Artesani, A., et al.
(författare)
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Monitoring metal ion leaching in oil-ZnO paint systems with a paramagnetic probe
- 2019
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Ingår i: Microchemical Journal. - : Elsevier BV. - 0026-265X. ; 151
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Tidskriftsartikel (refereegranskat)abstract
- Zinc oxide (ZnO), used as a pigment since the 19th C., is highly reactive when mixed with drying oils. Indeed, the combination of metal-based pigments and drying oils may react to form metal complexes in paint, which may lead to the aggregation of metal carboxylates or soaps. Whereas the mechanism and chemistry behind metal soap formation has been studied in depth, little research has focused on the changes that affect the inorganic pigment particles. In this work, we concentrate on the first phase of these reactions and monitor the evolution of an oil-ZnO paint system through Electron Paramagnetic Resonance (EPR) spectroscopy. By employing CuII as a paramagnetic probe, the progression of metal ion leaching from ZnO is followed through the switching of CuII from a silent tetrahedral coordination in ZnO bulk to an EPR active pseudo-octahedral coordination. Complementarily, the effective concentration of dissolved or extracted Zn and Cu is quantified through Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The experiment probes the spontaneous metal ion release in oil-based paint films and demonstrates that the kinetics of this phenomenon proceeds with a very steep increase in the first hours after mixing. This is followed by the saturation of the grow rate after a few days that we ascribe to the passivation of the ZnO pigment surface by carboxylate groups, which hinders the further leaching of metal ions, leading to a steady-state before the complete hardening or oxidation of the paint film. © 2019
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| 3. |
- Bargigia, Ilaria, et al.
(författare)
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Diffuse optical techniques applied to wood characterisation
- 2013
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Ingår i: Journal of Near Infrared Spectroscopy. - : SAGE Publications. - 0967-0335 .- 1751-6552. ; 21:4, s. 259-268
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Tidskriftsartikel (refereegranskat)abstract
- We propose an optical method for non-invasive characterisation of wood samples based on two optical techniques: time-resolved diffuse optical spectroscopy and gas in scattering media absorption spectroscopy. While the latter is sensitive to gases present inside wood pores, the former extracts information on the bulk material regarding light scattering and absorption. Measurements on spruce samples, cut along different wood fibre directions, are presented to show an example of the advantages of this combined approach: by applying these two non-destructive techniques together, in fact, relevant information on wood such as porosity, permeability and moisture content can be assessed. Furthermore, the chemical composition, internal structure and the anisotropy due to the wood fibres can be investigated.
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| 4. |
- Giorgi, L., et al.
(författare)
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In-situ technical study of modern paintings part 1: The evolution of artistic materials and painting techniques in ten paintings from 1889 to 1940 by Alessandro Milesi (1856–1945)
- 2019
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Ingår i: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425. ; 219, s. 530-538
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier B.V. A complementary multi-analytical in-situ approach has been adopted for the investigation of a corpus of ten paintings dating from 1889 and 1940 by the Venetian painter Alessandro Milesi (1856–1945), from the collection of the International Gallery of Modern Art Ca’ Pesaro in Venice. Analyses were performed in situ with digital imaging, elemental and spectroscopic analysis. The analysis of pigments and binding media and their possible deterioration patterns were studied with a combination of X-Ray Fluorescence (XRF) Spectroscopy, External Reflection- Fourier Transform Infrared Spectroscopy (ER-FTIR) and Raman Spectroscopy. These analytical methods provide information regarding the evolution of the artist's palette and the painting techniques adopted in painting. Data suggest the widespread detection of zinc carboxylates, with implications for conservation and display.
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| 5. |
- Giorgi, L., et al.
(författare)
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In-situ technical study of modern paintings - Part 2: Imaging and spectroscopic analysis of zinc white in paintings from 1889 to 1940 by Alessandro Milesi (1856–1945)
- 2019
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Ingår i: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425. ; 219, s. 504-508
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier B.V. We present a multi-analytical in situ non-invasive study of a series of emblematic paintings by Alessandro Milesi (1856–1945)from the collection of the International Gallery of Modern Art Ca' Pesaro in Venice. Eight paintings dated from 1897 to 1910 were studied with imaging and spectroscopic techniques. White pigments were characterized by a combination of X-ray fluorescence spectroscopy which traced the presence of zinc-based pigments in Milesi's paintings, Raman Spectroscopy, Laser Induced Fluorescence (LIF)Spectroscopy and Time-resolved Luminescence Imaging. Time-resolved analysis of luminescence emissions revealed the nanosecond emission from organic compounds and the slower emission from the luminescent inorganic pigment Zinc Oxide that varied between 1.1 and 1.6 microseconds. In this work, data regarding the distribution of luminescent pigments was acquired with a time-gated imaging detector. Furthermore, differences in emission decay kinetics recorded from different paintings can be ascribed to different paint formulations or origins of the Zinc white in paint.
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| 6. |
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Heritage Wood : Investigation and Conservation of Art on Wood
- 2019
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This volume highlights recent research efforts in the conservation and investigation of works of art on wood. Through eleven case studies it showcases different experimental methods ranging from X-ray analysis of objects to the study of cross-sections made from micro-samples. New research focusing on the technical study, treatment and assessment of works of art on wood in its many forms is featured in this edited volume. Technical studies include the attribution and investigations of a triptych by Hans Memling and a sculpture from workshop of Michel and Gregor Erhart, decorated Syrian rooms, and investigations of finely carved Gothic wooden objects. Synchrotron-based methods are presented for studying the alteration of 19th c. verdigris in Norway, and multi-analytical methods are employed for the investigations of 16th to 19th c. East Asian lacquer from the Kunsthistorisches Museum in Vienna. Novel methods for the cleaning of gilded surfaces using gels and emulsions are shown, as are innovative strategies for the consolidation for waterlogged wood, providing key data for the assessment of risks and benefits of new methods, and the short and long-term effects on gilding layers and archaeological wood. The book clearly shows how collaboration between engineers, physicists, biologists and chemists and conservators of different types of materials can lead to new research in conservation science. This book is crucial reading for conservators and conservation scientists, as well as for technical art historians, providing key methodological case studies of polychromy from different temporal and geographical contexts.
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| 7. |
- Izzo, Francesca, et al.
(författare)
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Multi-analytical Assessment of Bodied Drying Oil Varnishes and their use as binders in Armour Paints.
- 2021
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Ingår i: Heritage. - : MDPI AG. - 2571-9408. ; 4:4, s. 3402-3420
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Tidskriftsartikel (refereegranskat)abstract
- The characteristics of commercially available refined and bodied linseed and tung oils, used as binders in the production of armour paints after historic recipes, are explored. Employed as anticorrosive paints mainly from the 1920s to 1960s, armour paints are greener alternatives that can be used for protection in industrial heritage conservation. Using a multi-analytical approach, chemical and physical properties of the fresh oils and solid films before and after accelerated ageing (ISO 16474-2:2013) were investigated to better understand which features are beneficial for the technical function of armour paints. Tests included measurements of density, the refractive index, insoluble impurities, alkaline impurities, the water content, the iodine value, the saponification value, the free fatty acid concentration, the acid value, the peroxide value and colour (Lovibond) and cold tests. The characterisation of the fresh oils using molecular analysis with FTIR and GC-MS revealed the complexity of the commercial formulations, for which additions of semi- and non-drying oils were detected. The results show that organic paint binders follow complex chemical reactions (such as oxidation and decrease of unsaturation being variable or swelling following water-immersion tests), with implications for their suitability for use in protection.
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| 8. |
- Osticioli, I., et al.
(författare)
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Red lakes from Leonardo's Last Supper and other Old Master Paintings: Micro-Raman spectroscopy of anthraquinone pigments in paint cross-sections
- 2019
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Ingår i: Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy. - : Elsevier BV. - 1386-1425. ; 222
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of red particles in paint cross-sections from Leonardo da Vinci's Last Supper, Masolino da Panicale's wall painting Beheading of St. John the Baptist in Castiglione Olona, Tintoretto's The Discovery of the Body of Saint Mark and Paolo Veronese's Supper in the House of Simon has been carried out with micro-Raman measurements. Subtracted shifted Raman spectroscopy methods have been employed to resolve the signals in the presence of fluorescence. Taking advantage of the vibrational assignments based on recent ab initio calculations of aluminum-complexes of anthraquinones, the approach allowed the discriminate between anthraquinone dyes and lakes based on kermesic and carminic acids present in the studied samples for the first time without heavy sample treatment. (C) 2019 Elsevier B.V. All rights reserved.
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