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The control of humidity between certain limits is essential to avoid the alteration of historical objects, such as unstable historical glasses. However, the usual limits can be altered due to the presence of volatile organic compounds. This work presents the results of the exposure of soda, potash, and mixed‐alkali silicate glasses to neutral and acidic (formic) atmospheres with ∼30%, ∼70%, and ∼100% relative humidity. The hygroscopic capacity of the glass was analyzed by gravimetry, and the surface alteration was evaluated by infrared spectroscopy, optical microscopy, and ion chromatography. In all glasses, the alteration begins with alkali ions' lixiviation followed by the silica network's hydrolytic attack. The results showed that soda and mixed‐alkali silicate glasses exhibit similar behavior, while the potash‐lime one experienced the fastest degradation due to its composition. Results also confirmed that high humidity increased the alteration rate causing a higher hygroscopicity and reactivity of glasses. Finally, acidic environments promoted the ion‐exchange reaction at high humidity, accelerating the lixiviation of alkaline ions and promoting the diffusion of water into the glass network. [ABSTRACT FROM AUTHOR]

Historic glasses can be altered in the presence of inorganic pollutants, such as CO2, SO2, or NO2, but also, by the volatile organic compounds emitted by the museum cabinets. Among these pollutants, compounds with carbonyl groups such as acetic and formic acids, and formaldehyde are the most common ones. In this work, a study of the interaction of these contaminants with three of the most relevant historical glasses was carried out. These glasses were soda silicate glass, potash silicate glass, and lead crystal glass. Two alteration tests were carried out in these glasses in the presence of water, acetic acid, formic acid, or formaldehyde. In the first test, the alteration induced by the liquid solution was evaluated by the pH monitoring and the study of the ions lixiviated by inductively coupled plasma optical emission spectroscopy. In the second study, the alteration with gaseous contaminants was carried out. The hygroscopic capacity of the glasses was analyzed by gravimetry, the evolution of the glass surface by Fourier transform infrared spectroscopy in attenuated total reflectance mode, and the ions found on the glass surface by ion chromatography. These methods allowed to observe the different degradations that occurred in the three glasses in the presence of different pollutants in aqueous or gaseous environments. [ABSTRACT FROM AUTHOR]

The present work aims to study the glasses commonly named crystal glass produced in Portuguese factories from the 18th to the 20th centuries through their arcana or batch books. Recipes for colorless crystal glasses were selected, analyzed, and reproduced in the laboratory. Five recipes were chosen from the Marinha Grande arcanum, five recipes from the Gaivotas' Factory arcanum, and three recipes from the Castro and Oliveira Guerra arcanum. To characterize the composition and thermal‐physical properties of reproduced glasses, different analytical techniques were used such as micro‐energy dispersive X‐ray fluorescence, µ‐ Raman spectroscopy, differential scanning calorimetry, dilatometry, Vickers hardness, optical microscopy, and UV‐Vis absorbance spectroscopy. The selected recipes were proven viable for reproduction and the obtained glasses presented good thermal properties that allow the workability and creation of objects. It was also proven that there is a similarity in terms of chemical composition to some of the historical glasses attributed to Portuguese production in Portuguese museums. [ABSTRACT FROM AUTHOR]

Some historical glasses (lead‐wood ash glasses, lead‐crystal glasses...) are silicate glasses with high content of lead and potassium. This work presents the evaluation of the chemical stability of high‐lead glasses in a high relative humidity atmosphere and as result of aqueous immersion. In both situations, the alteration mechanism begins with the lixiviation of alkali metal and lead ions, followed by the hydrolytic attack of the silica glass network. According to the results, the glasses with a higher content of lead show the fastest degradation due to their higher hygroscopicity. Environmental CO2 can be dissolved in the adsorbed water and favor the formation of intermediate degradation compounds. [ABSTRACT FROM AUTHOR]

Abstract: The research on manuscripts provides useful information about the artistic/technical production and the scientific development in the past. However, the reproduction of the ancient recipes is difficult because most of them are described generally or they hide essential information to preserve the production secrets. In this study, four different recipes from the medieval Manuscript H‐490 (École de Médicine of Montpellier University, France) were reproduced. The raw materials and the production process of each recipe were discussed from the point of view of the glassmaking, and the final products were characterized. The recipe (31) indicated the preparation of a white glaze, similar to Islamic frits. The recipes (32) and (33) explained the preparation of an “unbreakable” glass; however, the characterization of the final products showed that no changes in the hardness of the glass were obtained. And the recipe (34) described the preparation of a green glass which was successfully obtained. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the analyses of infrared thermography images of two stained‐glass windows with the objective of the in situ characterization of this type of artworks. The analyses were carried out by active thermography. The observations revealed that glasses absorbed the long‐wave IR radiation emitted by the halogen lamps and their apparent surface temperature progressively increased. After switching the spotlight off, they experienced a progressive decrease in temperature. Silver stained glasses presented the same thermographic behavior than uncolored glasses because silver nanoparticles were too small or the yellow layer was too thin to produce a different response than the base glass with the IR radiation. The apparent surface temperature of enamels and grisailles depended on their thickness and color. Lead cames maintained an almost constant surface apparent temperature, except those painted that behave in a similar way than enamels. Metallic tin‐lead welds experienced the most important variation in the surface apparent temperature in reflection mode due to the energy reflected by the surface of the weld. Glass defects such as big bubbles were also observed. [ABSTRACT FROM AUTHOR]

This paper reports the research on the physical-chemical response of silicate glasses subjected to the action of three natural soils types: acidic, neutral, and basic. The main goal of the study was to characterize the corrosion mechanisms acting upon glasses formulated with chemical compositions that are commonly found in historical glasses through an accelerated aging test that replicates natural burial. Resulting data showed a distinct and recognizable response of each glass type, with pH as the key variable for glass corrosion. Results can be of great significance to historical glass studies, especially in choosing suitable conservation strategies for archeological findings. [ABSTRACT FROM AUTHOR]