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Conservation of glass mosaics in epoxy bedding
Viková, Barbora ; Vojtěchovský, Jan ; Hampl, Petr ; Svoboda, David ; Kučerová, Irena
The procedure focuses on the conservation of glass mosaics from the second half of the 20th century, which were embedded into epoxy resin as part of the original technology. The advantage was to create light, easily transportable structures (panels). Various materials were used for the base of these panels, such as steel reinforcement, aluminium plates, but also chipboard plates. Over time, the epoxy bedding proved to be unstable, especially in outdoor conditions, where it often degraded or completely disintegrated. It was therefore necessary to consider replacing the original bedding material with a new one. The replacement of the support is illustrated in the conservation of three mosaics, namely a glass mosaic with chipped tesserae, which is an example of an epoxy-coated mosaic with an embedded metal structure, and two mosaic of crumpled tesserae representing a mosaic glued with an epoxy resin to the chipboard. For both types of mosaics a brand new, more stable mosaic embedding system has been developed.
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Comparison of optical methods for characterization of glass mosaic weathering
Kocour, Vladimír ; Petráňová, Veronika ; Valach, Jaroslav
The work presented in this paper is a part of research project supported by Ministry of Culture and devoted to conservation of precious mosaic of 'Last Judgement' on St. Vitus Cathedral in Prague. The aim of the project is to enhance external protective polymeric coating on glass tesserae of mosaic and also to develop optical method for assessment of coating’s surface conditions. The paper concentrates on comparison of various methods for surface evaluation assesses their advantages and disadvantages and also discusses their suitability for long term monitoring of coating state, namely reflectometry, scanning probe microscopy, nanoindentation, white-light interferometry, and scanning electron microscopy. It is found that white-light interferometry and reflectometry methods are the most suitable ones for monitoring purposes.
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Signs of degradation of czech art nouveau mosaic glasses
Rohanová, D. ; Švarcová, Silvie ; Hájek, T.
Analyses of Art Nouveau mosaics from the church of St. Simon and Juda in Dolín near Slaný and from Holovousy, both most likely made by the workshop of Viktor Foerster, have shown that the author used the NaO-PbO-SiO 22 glass type and that he used the same glass also for restoration of The Last Judgment mosaic at the Prague Castle in 1890-1910. Despite the fact that lead glasses are more durable than potassium glasses, the material investigations identified corrosion processes on the surface of the glass pieces (tesserae) depending on their composition. Apart from the analyzed mosaic NaO-PbO-SiO2 glasses, we also used ancient sodium glasses (NaO-CaO-SiO2) and 22 potassium glasses (K2O-CaO-SiO2) from archaeological finds in Opava to demonstrate their different chemical durability. We also paid attention to fixation binders used in Art Nouveau mosaics. Inappropriate use of gypsum-containing binders is a significant cause of disintegration of the mosaics. Gypsum and gypsum-lime plasters are very sensitive to humidity. Capillary action of water is a very serious problem that endangers the overall lifespan of any mosaic.
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Signs oF degradaTion oF czech arT nouveau mosaic glasses
Rohanová, D. ; Švarcová, Silvie ; Hájek, T.
Analyses of Art Nouveau mosaics from the church of St. Simon and Juda in Dolín near Slaný and from Holovousy, both most likely made by the workshop of Viktor Foerster, have shown that the author used the NaO-PbO-SiO 22 glass type and that he used the same glass also for restoration of The Last Judgment mosaic at the Prague Castle in 1890-1910. Despite the fact that lead glasses are more durable than potassium glasses, the material investigations identified corrosion processes on the surface of the glass pieces (tesserae) depending on their composition. Apart from the analyzed mosaic NaO-PbO-SiO2 glasses, we also used ancient sodium glasses (NaO-CaO-SiO2) and 22 potassium glasses (K2O-CaO-SiO2) from archaeological finds in Opava to demonstrate their different chemical durability. We also paid attention to fixation binders used in Art Nouveau mosaics. Inappropriate use of gypsum-containing binders is a significant cause of disintegration of the mosaics. Gypsum and gypsum-lime plasters are very sensitive to humidity. Capillary action of water is a very serious problem that endangers the overall lifespan of any mosaic.
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