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Characterisation and chemical modification of halloysites
Vašutová, Vlasta ; Hradil, David (advisor) ; Pospíšil, Miroslav (referee)
Twelve halloysites from different sources in Slovakia, Turkey, China, New Zealand and U.S.A. have been characterized by combination of analytical methods together with the commercial sample of halloysite supplied by Sigma-Aldrich. The aim of this work was to select suitable candidates for to be used as carriers of porphyrine photoactive molecules. In nature, the formation of halloysite is related to the weathering of magmatic rocks or to the hydrothermal alteration of volcanic rocks, frequently in the contact with limestones. Halloysite belong to the kaolinite group, but, contrarily to kaolinite, it contains molecules of water in the interlayer space. It occurs in two forms: hydrated halloysite (10 ?) and dehydrated halloysite (7 ?).Dehydrated halloysites contain more admixtures than hydrated ones ? typically kaolinite, quartz, cristobalite, alunite, gibbsite and in one case also potassium mica. In samples containing both dehydrated halloysite and kaolinite their 001 diffractions overlap. Interaction with formamide was used in these cases to increase the interlayer space of halloysite and thus shift its basal diffraction to lower angles. The basal 001 diffraction of kaolinite after this treatment remains on 7 ?. Silver thiourea method (AgTU) was used to measure the cationic exchange capacity (CEC). Silver...
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Aplikace environmentální rastrovací elektronové mikroskopie (EREM) v oboru analýzy miniatur: metodika pro specifické použití ve výzkumu miniaturního malířství
Hradil, David ; Hradilova, Janka ; Neděla, Vilém ; Tihlaříková, Eva
The methodology deals with a completely new, unused procedure of non-invasive analysis of painted portrait miniatures, using environmental scanning electron microscope with an energy-dispersive X-ray spectrometer (ESEM-EDS). ESEM, unlike the conventional scanning electron microscope (SEM), allows the analysis of the painting on the ivory support, which is not possible in the gas pressure approaching the vacuum, where there is a risk of deformation and damage due to the drying of this biological material. Instead of an inert gas (nitrogen, argon), the aim is to use a mixture of nitrogen and water vapor at a defined pressure corresponding to the required relative humidity in the measuring chamber. This enables a completely non-invasive analysis of painted miniature objects on organic types of supports. This methodology is divided into two parts: morphological analysis and elemental composition analysis. The first case involves the study of morphological details at high magnification (e. g. the possibility of distinguishing different types of supports or characterizing their microstructure). The second part describes the implementation of elemental analysis in high spatial resolution (distinction of individual pigment grains).
Fulltext:  PDF; PDF
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Lead soaps in paintings: symptoms and the role of humidity
Garrappa, Silvia ; Švarcová, Silvie ; Kočí, Eva ; Hradilová, J. ; Bezdička, Petr ; Hradil, David
In this study, an overview of the symptoms of lead soaps reported in artworks in combination\nwith the study of the role of humidity on the formation of these degradation products have\nbeen thoroughly investigated. The use of optical microscopy, scanning electron microscopy\n(SEM) in combination with Fourier-transform infrared spectroscopy (FTIR) proved to be an\nefficient analytical approach to highlight both the saponified area of artworks’ samples and the\nformation of metal carboxylates within mock-up model systems. Optical microscopy revealed\nto be very useful for the first screening of samples embedded in resin, while SEM helped in\nthe detection and distribution of elements within the cross-sections. On the other hand, FTIR\nmicroscope proved to be a very powerful instrument for high-resolution point measurements\nperformed in the attenuated total reflection mode (ATR) mode with mercury-cadmium-telluride\n(MCT) detector, as well as for chemical imaging of larger area of both artworks’ and mock-up\nsamples performed in the ATR mode with focal plane arrays (FPA) detector. This study provides\nnew useful insights contributing to better understanding of factors affecting the paints‘ stability,\nwhich is neccesary for developing new efficient strategies for preservation and restoration of\nfatty-based painted artworks.
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Non-invasive material and traceological research of the stone head from Celtic settlement Závist near Prague
Cihla, M. ; Trefný, M. ; Drda, Petr ; Hradil, David ; Hradilová, J.
The sandstone head sculpture from the hillfort of Závist in the southern periphery of Prague has been subjected to a non-invasive survey by mechanoscopic and analytical approaches. A 3D model of a sculpture has been created using laser scanning and photogrammetry. A reconstruction of stonemason's working tools was derived from longitudinal and transversal sections of the traces on the head's surface. Further screening of the surface by handheld X-ray fluorescence identified increased contents of lead and tin suggesting a former intentional coloring of the sculpture's surface. Traces of gold could indicate that the surface was gilded. It was confirmed that the sculpture was originally not a part of a human figure, but was intended to represent only a self-standing head. The way of making as well as the nature of the original surface treatment has excluded the possibility that the stone head from Závist was a modern replica.
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The origin issue of the head of John the Baptist from Tajov
Hradilová, J. ; Bezúchová, E. ; Hradil, David ; Šídová, K.
The significant work of art, the Head of John the Baptist from Tajov, from the Museum of Central Slovakia in Banska Bystrica, which is probably part of the works of Niclaus Gerhaert von Leiden (1420/30 - 1475), was subject to conservation as well as detailed material analysis - first using non-invasive methods (radiography computer tomography, X-ray fluorescence), then laboratory analysis of taken samples (elemental and phase analysis, analysis of organic binders, dendrochronology, radiocarbon dating). The specific painting technique was described. Gilding of the head was performed without any ground only on brown preparatory layer for oil gilding (mixtion), however, the incarnates with an oily binder did contain a light dolomitic ground layer. The blood drops painting employed madder lake including sheep wool shearlings. The work consists of two parts - the head and the bowl, which was understood not to be original. Both parts are made from poplar wood. The results of the dating indicate that the head was created in the second half of the 15th century. The bowl could have been added later, but no later than the beginning of the 16th century. Its inclusion may have happened (albeit it is less probable) in the 17th century, but any period of time after that can be ruled out. The original colouring of the bowl was different the earth pigments of specific composition used in the ground layer imitated terracotta - a clay bowl. Based on the location of the existing hanging points the head was probably on display occasionally in a vertical position with a slight bottom view of 45 degrees.
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Mineralogical analysis of historical paintings
Čermáková, Zdeňka ; Hradil, David (advisor) ; Kanický, Viktor (referee) ; Artioli, Gilberto (referee)
Historical painted works of art have a very complex inner structure. The period painting technique led to the execution of a ground layer followed by several layers of underpainting and a top paint layer, over which a layer of glaze has been applied to increase the resistance to external wear. Each of these colour layers is composed of a dye or a pigment (or their mixture) bound by organic binder. Throughout the history, pigments were commonly prepared from minerals, either extracted from natural deposits or created artificially. In these heterogeneous layers containing both inorganic and organic components, undesirable degradation changes either driven by processes taking place directly in the colour layer or influenced by external agents may occur. Mineralogical approach, which focuses primarily on the structure of studied pigments, helps in the clarification of the occurring processes, in the determination of conditions leading to degradation as well as in the identification of original/degradation phases. Furthermore, it can be profitably applied in the micro- analysis of mineral pigments present in tiny micro-samples obtained from works of art, contributes to the artwork's provenance/authorship studies and the determination of regional provenance of the employed mineral pigments. This Ph.D....
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Paleoenvironmental record of carboniferous lacustrine deposits of central and western Bohemian basins: analysis and korealiton of mineral and biogenic proxies
Lojka, Richard ; Hradil, David (advisor) ; Hladil, Jindřich (referee) ; Janočko, Juraj (referee)
Ph.D. thesis represents summary of multidiciplinary palaeoenvironmental and palaeoclimatic research of the most significant Late Pennsylvanian lacustrine horizon of the central and western Bohemian basins - the Malesice Member of the Slaný Formation. Two cores from new shallow drills, situated 80 km apart, were analysed. Multidisciplinary approach is based on description of lamination structure and periodicity; mineral and isotopic composition of autigennic carbonates, namely siderite; compositiona of detrital minerals including clay mineral assemblages; and composition of autochthonous and allochthonous organic particles including palynospectra. Detailed analysis of drill cores lead to the identification of individual phases of lake development linked with lake-level fluctuation and water-column stratification, which were driven by a sume of precipitation and its seasonal distribution. Changes in precipitation also affected compostion and density of vegetational cover in the lake surroundings, weathering intesity of source rocks and degradation of organic matter in the drainage basin, and so precipitation affected final grain-size and composition of detrital material deposited in the lake. Beside common environmental signatures at both studied sites, there are also significant...
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Materials research of colour layer on art works
Grünwaldová, Veronika ; Hradil, David (advisor) ; Feltl, Ladislav (referee) ; Kratochvíl, Bohumil (referee)
Charles University in Prague Faculty of Science Department of Analytical Chemistry SUMMARY OF PhD THESIS Material Research of Colour Layer in Artworks Ph.D. programme: Analytical Chemistry Ing. Veronika Grünwaldová Prague 2010 2 Contents 3 CONTENTS Introduction and literature search.............................................................. 4 Experimental section.....................................................................................5 1. X-ray powder microdiffraction ...............................................................5 1.1. Analysis of fragments and cross-sections ...........................................................6 1.2. Preparation and analysis of microtome slices.....................................................7 2. Microscopy methods and image analysis................................................8 2.I. Test of minimum necessary resolution - model shapes and real samples ........9 2.2. Possibilities of using EDX mapping of elements.................................................12 2.3. Qualitative and quantitative characterization of selected pigments in real colour layers .............................................................................................................................13 3. Mobile X-ray...
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Characterisation and chemical modification of halloysites
Vašutová, Vlasta ; Pospíšil, Miroslav (referee) ; Hradil, David (advisor)
Twelve halloysites from different sources in Slovakia, Turkey, China, New Zealand and U.S.A. have been characterized by combination of analytical methods together with the commercial sample of halloysite supplied by Sigma-Aldrich. The aim of this work was to select suitable candidates for to be used as carriers of porphyrine photoactive molecules. In nature, the formation of halloysite is related to the weathering of magmatic rocks or to the hydrothermal alteration of volcanic rocks, frequently in the contact with limestones. Halloysite belong to the kaolinite group, but, contrarily to kaolinite, it contains molecules of water in the interlayer space. It occurs in two forms: hydrated halloysite (10 ?) and dehydrated halloysite (7 ?).Dehydrated halloysites contain more admixtures than hydrated ones ? typically kaolinite, quartz, cristobalite, alunite, gibbsite and in one case also potassium mica. In samples containing both dehydrated halloysite and kaolinite their 001 diffractions overlap. Interaction with formamide was used in these cases to increase the interlayer space of halloysite and thus shift its basal diffraction to lower angles. The basal 001 diffraction of kaolinite after this treatment remains on 7 ?. Silver thiourea method (AgTU) was used to measure the cationic exchange capacity (CEC). Silver...
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Paleoclimatic reconstruction based on biogenic and abiogenic proxies from Baikal Lake and Aral Sea sedimentary records
Píšková, Anna ; Hradil, David (advisor) ; Pokorný, Petr (referee) ; Houk, Václav (referee) ; Boomer, Ion (referee)
1. ABSTRACT Lake sediments represent an important source of valuable information about the past climate in continental environment. They consists of a mixture of autochthonous and allochthonous organic and inorganic components both responding to paleoenvironmental changes in the water bodies and watershed. Both the composition and relative content of individual sedimentary components mirrors the climate changes. The main inorganic components in lake sediments are quartz, carbonates, and clay minerals; organic matter embodies various plants and animal remains. Reconstruction of past climate is possible only when an efficient combination of analytical methods allowing characterization of all these components is used. We have provided such multi proxy and high resolution analysis on two cores from two lakes, Aral Sea and Baikal Lake. These two large Asian water reservoirs have got a large watershed, originated tectonically, and have grabbed scientific attention during the last decades. Aral Sea represents a closed lake system in semi-arid area and therefore Aral Sea sediments mirrors even minor environmental changes. Research performed on Aral Sea sedimentary cores aims to unravel past lake level variations and to determine their leading forces. Ten radiocarbon dates have been used to construct the age model...
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