Ceramics from the magnesia-alumina-silica (MAS) system are common products of the ceramic industry. The phase composition of these systems can be rather complex, especially when feldspar is added as ...a flux, and thus attempts to correlate the composition and structure of these ceramics to their properties are quite rare, especially when considerable amounts of glass phase and sapphirine appear after firing. In this paper an attempt is made to correlate, for a talc-kaolin-alumina-feldspar mixture resulting in cordierite-sapphirine ceramics after firing to 1250 °C, the resulting elastic properties (Young’s modulus), as determined via the impulse excitation technique (IET), with the phase composition, determined via X-ray diffraction (XRD). Moreover, it is shown how the evolution of the phase composition and microstructure is reflected in the temperature dependence of Young’s modulus and damping during heating-cooling cycles with maximum temperatures ranging from 1000 to 1250 °C.
The presence of metal soaps is well documented in paintings originating from the 15th century onward, and in numerous cases, the soaps`formation is attributed to environmental factors, like relative ...humidity, light exposure and/or high temperature. Understanding the formation mechanism, involving effects of these particular factors during artwork`s realization, is crucial for the search of suitable conservation and preservation strategies.
In the present study, the role of humidity on the formation of metal carboxylates and other secondary products in mixtures of lead-based pigments (i.e., minium, lead-tin yellow and lead white) with linseed oil was described within the experimental drying of model paints. Samples were exposed to various relative humidity conditions and the processes were monitored by Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD) involving both the hourly measurements for the monitoring of immediate processes and long-term (up to two months) monitoring to evaluate secondary changes.
The acquired data clearly demonstrated the influence that the different levels of humidity may have on the formation of lead carboxylates during the painting's drying. The selected methods were efficient in the reaction monitoring and provided new insights leading to a better understanding of factors affecting the metal soaps' formation in paints.
•Determination of methanol, formaldehyde and formic acid in drying oils.•Simple, cost-effective, and reliable QuEChERS-dSPE/HPLC–DAD method validated.•Efficient clean-up of oil extracts by ...nanostructured metal oxides ZrO2 and CeO2.•Method suitable for monitoring of quality of drying oils for restoration treatment.
The determination of secondary volatile degradation products in drying oil extracts is substantial to prevent formation of undesirable metal formates in paintings and/or other artefacts. This study develops a simple, cost-effective, and reliable, high-performance liquid chromatography with diode array detector (HPLC–DAD) method to determine three secondary volatile degradation products (methanol, formaldehyde, and formic acid) in drying oils, including linseed, poppy-seed, and walnut oil. Extraction of analytes was performed using QuEChERS-based procedure followed by metal oxide-based dispersive solid-phase extraction (d-SPE) clean-up and presented a good performance for all of the volatile analytes of interest with recoveries in the range of 90–120% after application of the nanostructured cerium oxide-based (CeO2) and zirconia-based (ZrO2) sorbents prepared by favorable and ecological-friendly methods. With a new clean-up solution for samples with high-fat content, it was possible to achieve higher recoveries than with commercial Z-Sep/C18 sorbent. In all cases, relative standard deviations (RSD) of less than 10% were achieved. No significant matrix interference was observed due to the application of effective sorbents in nanostructured form. The developed method was applied to samples of drying oils, and it was found that after storage for three months, all methanol was most likely oxidized to formaldehyde and formic acid. The concentrations of formaldehyde were in the range of 260 - 304 μg∙g−1, while formic acid concentrations ranged between 72 - 386 μg∙g−1. The highest concentration of formaldehyde (304 μg∙g−1) and formic acid (386 μg∙g−1) was found in linseed oil.
The evolution of Young’s modulus and damping is investigated for Czech kaolins in situ via the impulse excitation technique (IET) from room temperature to 1250 and 1400 °C. During heating the ...processes of drying, dehydroxylation, spinel formation, mullitization, silica release and glass melting are clearly discernible. During cooling Young’s modulus increases, exhibiting a flat maximum around 800 °C and a steep decrease below 200 °C when the cristobalite content is high. Differential IET curves are introduced as a new representation of IET results, and damping curves are shown to provide additional information. The phase composition is determined via XRD, including the glass phase. Based on the densities, Young’s moduli and volume fractions of the individual phases, the densities and Young’s moduli of the kaolin-based ceramics are calculated and compared to theoretical predictions, showing that Young’s modulus is nicely predicted by a benchmark relation for partially sintered ceramics with concave pores.
Even though many studies have reported about the impacts of shape, length and distribution of steel fiber reinforcement on global concrete properties, there is a lack of information about the ...influence of coating type of steel fibers on high temperature resistance of concrete. This paper describes the effect of Cu-Zn coated steel fibers on selected properties of reactive powder concrete (RPC) after exposure to elevated temperatures. The initial corrosion of zinc in Cu-Zn surface layer is found to be already activated by the alkaline environment of the fresh concrete. The RPC samples reinforced with Cu-Zn coated steel fibers are heated to 600 °C and 1000 °C, and the influence of thermal load on microstructure, basic physical, mechanical, thermal and durability properties is analyzed. Based on the obtained results, it can be concluded that the maximal temperature to maintain effectiveness of the RPC reinforced with Cu-Zn steel fibers is 600 °C.
Clay-based pigments are among the most traditional. Unlike other mineral pigments, they have never been fully replaced by synthetic analogues and are still used in painting today. Since their ...analysis requires a specific approach, detailed distinction of clay pigments has never been a part of routine chemical-technological research in fine arts—regardless of a great potential of clay minerals for determining regional provenance of the material. This review article maps and summarizes research on clay pigments in historical paintings that has been systematically pursued by authors since the beginning of this millennium. This rallying and interconnection of knowledge was an opportunity for a new reflection on the common aspects of these research projects, either methodological or interdisciplinary, since these findings are closely related to art-historical evaluation of artworks. It offers a comprehensive insight into the microanalysis of clay pigments with using powder X-ray micro-diffraction and complementary methods. Significant new findings come, for example, from research on the Italian Baroque. It becomes clear that cheap availability of raw material, pottery clays, could have played an important role in the change in painting technology at the turn of the 16th and 17th centuries.
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•A rare wood ash glass tessera from Malbork Madonna was studied in detail.•It was found to be original mediaeval, from the area north of Alps, coloured by Co.•Opacification was ...achieved by Ca-phosphate grains, a Mediterranean technology.•Two phases detected in tessera for the first time: leucite and pseudowollastonite.•Pseudowollastonite indicates production temperature above ca. 1125 °C.
While the natron and plant ash glass tesserae may be found on places of importance across the former Roman and Byzantine empires, wood ash glass tesserae are scarce. This is the first time a wood ash glass tessera is studied in detail. It was part of a magnificent 8-metres tall statue of Madonna in Malbork, Poland, created at the end of the 14th century and destroyed at the end of World War Two. It was found to be coloured by cobalt with possible impact of copper, and opacified by Ca-phosphate. Processes previously described in sodium-rich glasses were observed also in the studied potassium-rich wood ash glass tessera, such as diffusion of the respective alkali metal into the Ca-phosphate grains. The elemental composition of the tessera indicates that it is original – mediaeval, from the area north of Alps. Two phases were identified for the first time, to authors’ best knowledge, in any glass tessera – leucite (tetragonal KAlSi2O6) and pseudowollastonite (monoclinic CaSiO3). As pseudowollastonite is a high-temperature phase, it may serve as an indicator of production temperature, which was further supported by the study of polymerisation index of model glasses. This study contributes to the knowledge of old technologies and showed that the know-how for opacification was imported from the Mediterranean, while the raw materials employed for the base glass preparation were from the area north of Alps.
The influence of added sucrose on the phase composition of iron oxide nanoparticles was studied in the Fe2O3/SiO2 nanocomposites. The nanocomposites were prepared by impregnation of mesoporous silica ...SBA-15 with iron nitrate containing various amounts of sucrose and their subsequent annealing at 1100 and 1200 °C. The phase composition of the iron oxide nanoparticles in the prepared nanocomposites was analyzed by X-ray diffraction and 57Fe Mössbauer spectroscopy on polycrystalline samples. Profile analysis of the X-ray diffraction maxima was used to determine the apparent crystallite size of the different polymorphs. The content of β-Fe2O3 in the samples increased with an increasing amount of sucrose, and no β-Fe2O3 was observed in the samples without sucrose. These samples contained only ε-Fe2O3 and hematite. The apparent crystallite size was found to be similar for both hematite and β-Fe2O3. Therefore, sucrose was identified as the primary variable, which directs the ε-Fe2O3 transformation to either hematite or β-Fe2O3. Our findings shift the way we understand the β-Fe2O3 formation from ε-Fe2O3 in the Fe2O3/SiO2 system from the size-directed to the starting material-directed transformation.
In the Baroque European painting technology, various coloured clays had been used to prime canvases. These clays are generally considered to be carefully selected in terms of colour and other ...technological properties (adhesiveness, ductility etc.), as the painting represented the most delicate field of fine art. However, it seems that the availability of the material at a given place as well as its price often played a much more significant role than previously thought. It led to the usage of highly heterogeneous cheap pottery clays in painting, even though they often had to be additionally coloured. For the first time, a clear evidence is provided that a very similar pottery clay material was applied in three different technological ways: i) as a clay body of an unfired terracotta statue created in Florence or Bologna at the end of 16th century, ii) as a secondary putty on the Renaissance painting by Antonello da Saliba (1466–1535), and iii) as a preparation layer – ground – of an oil-on-canvas paintings attributed to Italian Caravaggists (17th century) or also to Carlo Maratta or workshop (1655–1713). The identity of the material was confirmed by mineralogical analyses as well as description of nannofossils, which enable to date the clay to Eocene – Oligocene.
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•First application of micropalaeontology to calcareous clays in paintings•The same clays used in three ways (sculpture, canvas priming, filling)•Identical clay sources for sculpture and painting in Baroque Italy
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