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1.
Nati Salvadó Salvador Butí Marine Cotte Gianfelice Cinque Trinitat Pradell 《Applied Physics A: Materials Science & Processing》2013,111(1):47-57
A representative selection of green paintings from fifteenth century Catalonia and the Crown of Aragon are analyzed by a combination of synchrotron radiation microanalytical techniques including FTIR, XRD, and XRF. The green pigments themselves are found to be a mixture of copper acetates/basic copper acetates and basic copper chlorides. Nevertheless, a broader range of green shades were obtained by mixing the green pigment with yellow, white, and blue pigments and applied forming a sequence of micrometric layers. Besides the nature of the pigments themselves, degradation and reaction products, such as carboxylates, formates and oxalates were also identified. Some of the copper based compounds, such as the basic copper chloride, may be either part of the original pigment or a weathering product. The high resolution, high brilliance, and small footprint of synchrotron radiation proved to be essential for the analysis of those submillimetric paint layers made of a large variety of compounds heterogeneous in nature and distribution and present in extremely low concentrations. 相似文献
2.
N. Salvadó S. Butí E. Pantos F. Bahrami A. Labrador T. Pradell 《Applied Physics A: Materials Science & Processing》2008,90(1):67-73
The high analytical sensitivity and high spatial resolution of synchrotron radiation-based techniques, in particular SR-XRD
and SR-FT-IR, allows the identification of complex micrometric mixtures of compounds that constitute the different layers
of ancient paintings. The reliability of the measurements even with an extremely small amount of sampled material is very
high, and this is particularly important when analyzing art works.
Furthermore, the micro size (10×10μm for FT-IR and 30 to 50 μm squared spot size for XRD) of the beam enables one to obtain
detailed compositional profiles from the different chromatic and preparation layers. The sensitivity of the techniques is
high enough for the determination of minor and trace compounds, such as reaction and weathering compounds.
We report here the identification of pigments in the Romanesque wall paintings found in situ in the church of Saint Eulàlia
of Unha place in the Aran valley (central Pyrenees). During the first centuries of the second millennium numerous religious
buildings were built in Western Europe in the Romanesque style. In particular, a great number of churches were built in the
Pyrenees, most of which were decorated with wall paintings. Although only a few of these paintings have survived, they represent
one of the most important collections of Romanesque art, both for their quantity and quality. A full identification of the
pigments, binder, supports, and reaction and weathering compounds has been obtained. The results obtained, in particular aerinite
as a pigment, indicate a clear connection between the paintings found in this Occitanian church and the Catalan Romanesque
paintings from the south bound of the Pyrenees.
PACS 61.10.Nz; 07.85.Qe; 82.80.Gk 相似文献
3.
T. Pradell J. Molera E. Pantos A.D. Smith C.M. Martin A. Labrador 《Applied Physics A: Materials Science & Processing》2008,90(1):81-88
Luster is a golden metallic-like decoration produced on glazed ceramics since early Islamic times (Iraq, 9th AD). Luster is
obtained by the reaction of a luster paint and the glaze surface over which it is applied. A temperature-resolved XRD experiment
was designed to study the high temperature reactions in the luster paint while the luster layer is formed. The luster paint
composition has been made based on the original luster paints found during the excavation of the 13th AD workshop site at
Paterna (Valencia).
The sulfo-reducing atmosphere created during the decomposition of cinnabar promotes the reduction of Cu2+ containing compounds to Cu+ and the presence of Hg vapours delays the precipitation of metal silver. Moreover, evidence of the formation of a melt in
which the copper and silver-containing compounds dissolve has also been obtained.
The thickness of the luster paint applied results in the formation of luster layers of different hues and colours. The use
of a mixture of copper and silver paint results in the formation of dark-brown luster layer similar to the ones produced in
early Islamic times in Iraq and showed also the characteristic blue iridescences.
PACS 81.05.Pj; 81.07.-b; 78.67.-n; 82.39.Wj 相似文献
4.
T. Pradell J. Molera C. Bayés P. Roura 《Applied Physics A: Materials Science & Processing》2006,83(2):203-208
Luster is a metallic decoration produced since early Islamic times (9th century AD in Iraq). Different studies have shown
that medieval lusters are a metal-glass nanocomposite (metal nanoparticles embodied in a silica glassy matrix) obtained from
the reaction of a copper and/or silver containing paint with a glaze. The mechanisms of formation of these metallic-like layers
are investigated by laboratory reproductions of Medieval luster. Copper and silver lusters are obtained based on different
thermal paths and atmospheres, and by using different glaze compositions. The ionic exchange between Cu+ and Ag+ ions from the luster paint with Na+ and K+ of the glaze, is demonstrated in either oxidizing or inert atmospheres and at firing temperatures between 500 °C and 600 °C.
The reduction of copper and silver to their metallic state is obtained by introducing a reducing gas afterwards. The lusters
are non-metallic red ruby copper or green with brown spots silver when developed over alkaline glazes, while they appear coppery
and golden metallic when developed over mixed alkaline-lead glazes. SR-XRD, optical absorption and microprobe chemical analysis
of the lusters indicate that the total amount of copper and silver, and the nature and size of the nanoparticles, are similar
in both cases. Further work is needed to clarify the origin of these differences.
PACS 81.05.Pj; 81.07.b; 81.16.Be; 78.67.Bf; 42.50.Fx 相似文献
5.
T. Pradell J. Molera N. Salvadó A. Labrador 《Applied Physics A: Materials Science & Processing》2010,99(2):407-417
The production of glass represented an important technological achievement, and it was the starting point for the invention
of a large variety of materials, produced by processes involving melting, partial or total, and precipitation of new crystalline
compounds during cooling. In particular, those crystallites built-in the glaze due to partial or total insolubility of some
elements originally present in the melt (for instance some colourants and opacifiers), as well as those crystallites formed
in the glazes resulting from the interaction of the melt and the ceramic surface are subject of the highest interest in the
study of glaze technology. Finally, devitrification and weathering gives rise to precipitation of new crystalline compounds
closer to the surfaces and interfaces. 相似文献
6.
Salvadó N Butí S Labrador A Cinque G Emerich H Pradell T 《Analytical and bioanalytical chemistry》2011,399(9):3041-3052
Altarpieces and polychrome carved wood from the fifteenth century AD usually exhibit golden and silvery areas by the application
of a very thin foil of metal. The metal foils were normally protected from the atmosphere by a varnish or resin which maybe
either preserved or absent. Moreover, they were glued to the background surface by adhesive substances (egg yolk, drying oil
or animal glue). The high proportion of the glueing substances often renders the development of reaction compounds. With time,
silver alters blacken or simply disappear completely. In this paper, we study the alterations to metal foils from a selection
of fifteenth century artworks showing different glueing agents, organic coatings and several degrees of conservation of the
organic coatings and metal leafs. The submillimetric layered structure and the high variability and low amount of most of
the compounds present in the different layers, as well as their differing nature (organic and inorganic) make the use of micron-sensitive
high-resolution techniques essential for their study. In particular, the high resolution, high brilliance and small footprint
renders synchrotron radiation most adequate for their study. SR-XRD was performed to identify the reaction compounds formed
in the different layers; μFTIR was used at to identify the silver protecting organic coatings, the metal foil glueing layers
and the corresponding reaction compounds. The results obtained suggest that atmospheric corrosion is the dominant mechanism,
and therefore that the degree of corrosion of the metal foils is mainly related to the conservation state of the protecting
coatings. 相似文献
7.
T. Pradell G. Molina J. Molera J. Pla A. Labrador 《Applied Physics A: Materials Science & Processing》2013,111(1):121-127
The compounds responsible for the colors and decorations in glass and glazed ceramics include: coloring agents (transition-metal ions), pigments (micro- and nanoprecipitates of compounds that either do not dissolve or recrystallize in the glassy matrix) and opacifiers (microcrystalline compounds with high light scattering capability). Their composition, structure and range of stability are highly dependent not only on the composition but also on the procedures followed to obtain them. Chemical composition of the colorants and crystallites may be obtained by means of SEM-EDX and WDX. Synchrotron radiation micro-X-ray diffraction (SR-micro-XRD) has a small beam size adequate (10 to 50 microns footprint size) to obtain the structural information of crystalline compounds and high brilliance, optimal for determining the crystallites even when present in low amounts. In addition, in glass decorations the crystallites often appear forming thin layers (from 10 to 100 micrometers thick) and they show a depth-dependent composition and crystal structure. Their nature and distribution across the glass/glaze decorations gives direct information on the technology of production and stability and may be related to the color and appearance. A selection of glass and glaze coloring agents and decorations are studied by means of SR-micro-XRD and SEM-EDX including: manganese brown, antimony yellow, red copper lusters and cobalt blue. The selection includes Medieval (Islamic, and Hispano Moresque) and Renaissance tin-glazed ceramics from the 10th to the 17th century AD. 相似文献
8.
9.
Identification of reaction compounds in micrometric layers from gothic paintings using combined SR-XRD and SR-FTIR 总被引:1,自引:0,他引:1
Synchrotron radiation X-ray diffraction (μ-SR-XRD) and Fourier transform infrared spectroscopy (μ-SR-FTIR) are used in the non-destructive identification of reaction and aging compounds from micrometric ancient painting layers. The combination of the micrometer size and non-destructive nature of the techniques together with the high resolution and brilliance of the synchrotron radiation has proved to be a procedure most advantageous for the study of reaction, aging and degradation processes. Copper, lead and calcium carboxylates and oxalates are determined in the chromatic, preparation and alteration layers from 15th century egg tempera and oil paintings. Their nature and crystallinity have been assessed. Some hypothesis about the mechanisms of development of both carboxylates and oxalates are presented. 相似文献
10.
Ana Flo Ana C. Calpena Antoni Díez‐Noguera Alfons del Pozo Trinitat Cambras 《Photochemistry and photobiology》2017,93(2):632-635
UV rays may cause several degrees of skin damage, which makes sunscreen research necessary. In addition, skin sensitivity shows daily variations, which can interfere in the detection of the efficacy of the filters. Here, we studied the UV‐induced erythema in hairless rats at two times of the day (light and darkness) using a colorimeter method. The effect of an emulsion with solar filters with or without melatonin was also assayed. Results indicate that the value of a* (from CIELAB color space values L* a* b) was the most useful variable to evaluate the erythema. However, at the UV intensity used, erythema was only detected when irradiation was carried out during the activity phase of the animal, enabling the detection of the protective action of the sunscreen at this time. Thus, daily variations in skin sensitivity have been demonstrated and should be taken into account in dermatological research. 相似文献