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Glass is often seen as a relatively stable material, unaffected by changes in environmental conditions, but recent studies indicate otherwise. Research on the atmospheric deterioration of glass has consistently shown a strong correlation between climate, especially relative humidity (RH), and the rate of deterioration. New studies by the authors have shown that even stable compositions are at risk, when the glasses are exposed to continuous broad fluctuations in RH and temperature. Letting standards slip for the long-term storage of glass can be devastating, eventually leading to irreversible damage that in the final stages can result in the complete destruction of an object. Current research and monitoring of collections at the Corning Museum of Glass indicates that the RH should be within the range of 40-50%. For already crizzled glasses, a tighter control to 40-42% is recommended. Analysis of compositions of already crizzled glasses is ongoing, and hopefully will lead to the identification of at least some groups of glasses that are more at risk. This will help in providing future environmental recommendations for identifiable compositions, selected glass types, or known manufacturers. [ABSTRACT FROM AUTHOR]

Glass is often seen as a relatively stable material, unaffected by changes in environmental conditions, but recent studies indicate otherwise. Research on the atmospheric deterioration of glass has consistently shown a strong correlation between climate, especially relative humidity (RH), and the rate of deterioration. New studies by the authors have shown that even stable compositions are at risk, when the glasses are exposed to continuous broad fluctuations in RH and temperature. Letting standards slip for the long-term storage of glass can be devastating, eventually leading to irreversible damage that in the final stages can result in the complete destruction of an object. Current research and monitoring of collections at the Corning Museum of Glass indicates that the RH should be within the range of 40-50%. For already crizzled glasses, a tighter control to 40-42% is recommended. Analysis of compositions of already crizzled glasses is ongoing, and hopefully will lead to the identification of at least some groups of glasses that are more at risk. This will help in providing future environmental recommendations for identifiable compositions, selected glass types, or known manufacturers. [ABSTRACT FROM AUTHOR]

The two Stangengläser, tall cylindrical vessels from the beginning of the seventeenth century, are described in detail. The severely damaged Stangengläser, decorated with diamond-point engraving and cold-painting, were challenging to treat. Research preceding the conservation revealed differences in decorating techniques. Samples of the paint layers were analyzed using micro-Fourier transform infrared spectroscopy. Two layers of resinous varnish with a middle layer of paint containing a plant gum were found on the Stangenglas with Allegory of Caritas and Zierotin coat of arms. In the plain paint layer of the Stangenglas with dancing couples, egg white was identified as the binder. The glasses, analyzed using scanning electron microscopy with energy dispersive X-ray spectrometry, had similar potash-lime-silica compositions, which seems to be characteristic for glass from Bohemian lands. Results of analysis contributed to the discussion about the possible provenance of the Stangengläser, the glassworks at Wilhelmberg, South Bohemia. [ABSTRACT FROM AUTHOR]