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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]

The scientific research output of individuals and institutions is commonly evaluated by the number of publications in journals with high impact factor and their corresponding citations. However, the interdisciplinary character of journals reporting advances in conservation science favors their spread over different categories of the Journal Citation Report (JCR). Here we report an analysis of the evolution of the impact factor, the percentile, and the citations on the JCR indexed conservation journals over the last ten years. Our analysis shows that of the 57 conservation journals indexed in the JCR, only eight of them have an impact factor. These journals are distributed across different categories in the Science Citation Index (SCI) and Social Science Citation Index (SSCI), and these categories are sometimes not suitable and decrease their metric impact. This analysis was complemented by a worldwide survey of conservation professionals on their opinions about publishing in these journals. The survey showed two different perspectives about conservation science journals in relation to the background and work of the responders. Conservators and restorers prefer conservation journals with case studies; while researchers prefer high-impact journals, even if they lie outside of the conservation area, so the overall impact factor of conservation journals remains low (low JIF, low Q values). This dichotomy could be fixed with the creation of a new category for heritage science journals in JCR. [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]

Grisaille is a glass-based paint made by mixing metal oxides (iron or copper) with ground lead-silica glass. The different materials used in the grisailles production (coloring agents, base glasses, or vehicles) can significantly impact their long-term stability along with the firing conditions. The main objective of this study was to achieve a better understanding of how raw materials influence the production and stability of these paints. To achieve this goal, 27 grisailles were produced, changing the raw materials, proportions, and firing conditions. The produced grisailles were characterized by X-ray fluorescence and diffraction, colorimetry, roughness measurement, and contact angle analysis. Adhesion and cleaning tests were also made. The use of different coloring agents has a significant impact on the final appearance and on the chemical and mechanical stability of the grisailles, but the latest is more affected by both firing temperature and the proportion between pigments and base glasses. [ABSTRACT FROM AUTHOR]

Stained glass restoration generally involves filling glass losses to maintain the coherence of the window and the new glasses used to fill the losses can be painted to chromatically reintegrate the stained glass panel. One of the most common painting materials on stained glass is grisaille, a paint made by mixing metal oxides with a ground lead glass. Grisailles usually have black and brown hues and are used for the creation of outlines as shadows in window glasses. Although several commercial companies sell many types of products to paint on glass, few of them present the necessary compatibility with the original materials that conservation materials must have. Debitus is one of the most renowned companies, and its grisailles are frequently used for chromatic reintegration in stained glass window restoration. Thus, the main objective of this study was to assess the long-term stability and durability of commercial Debitus grisailles. Two alteration tests were carried out, with samples placed in high humidity chambers and submerged in distilled water. The samples and degradation products were characterized by optical microscopy, µ-Raman spectroscopy, and colourimetry. In the immersion, the pH of the water was measured during the experiment, and the leached elements were analyzed at the end by inductively coupled plasma atomic emission spectroscopy. The results showed an alteration of the colour and the formation of degradation products, identified as sulphates. The solution pH was increased by the aqueous extraction of alkaline and alkaline-earth ions from the support glass of the samples. Despite these changes, it was possible to conclude that these commercial grisailles presented good durability and stability for use in conservation treatments. [ABSTRACT FROM AUTHOR]

Flashed glasses are composed of a base glass and a thin colored layer and have been used since medieval times in stained glass windows. Their study can be challenging because of their complex composition and multilayer structure. In the present work, a set of optical and spectroscopic techniques have been used for the characterization of a representative set of flashed glasses commonly used in the manufacture of stained glass windows. The structural and chemical composition of the pieces were investigated by optical microscopy, field emission scanning electron microscopy-energy dispersive X-ray spectrometry (FESEM-EDS), UV-Vis-IR spectroscopy, laser-induced breakdown spectroscopy (LIBS), and laser-induced fluorescence (LIF). Optical microscopy and FESEM-EDS allowed the determination of the thicknesses of the colored layers, while LIBS, EDS, UV-Vis-IR, and LIF spectroscopies served for elemental, molecular, and chromophores characterization of the base glasses and colored layers. Results obtained using the micro-invasive LIBS technique were compared with those retrieved by the cross-sectional technique FESEM-EDS, which requires sample taking, and showed significant consistency and agreement. In addition, LIBS results revealed the presence of additional elements in the composition of flashed glasses that could not be detected by FESEM-EDS. The combination of UV-Vis-IR and LIF results allowed precise chemical identification of chromophores responsible for the flashed glass coloration. [ABSTRACT FROM AUTHOR]

The most frequent cause of glass degradation is environmental moisture, which is adsorbed on its surface forming a hydration layer that induces the rupture of the glass network. This pathology is accelerated by the accumulation of volatile organic compounds (VOCs), like formic acid. Although there is extensive knowledge about their impact, concentrations inside display cases are difficult to reduce efficiently. This study presents the assessment of different materials to reduce the concentration of formic acid to mitigate the degradation produced in unstable glasses. With this objective, copper threads, steel wool, silica gel, and activated carbon were chosen as low-cost materials with good adsorption or reactivity to the VOCs, exposing them in desiccators to an environment of 100% RH and 10 ppm of formic acid. Given that silica gel obtained the best results, its optimization as a sorbent material was evaluated by maintaining, regenerating, or renewing it when exposed next to the same glass. The tests carried out concluded that the hygroscopic capacity of the glasses exposed with silica gel decreased and, therefore, a lower degradation is observed on its surface. In addition, regenerating and renewing weekly the silica gel improved the results. [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]

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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]

Several treatments appear in the bibliography to clean the tarnished silver. However, the information about the aspect and efficiency of the cleanings is spread or not completely detailed in these works. With this purpose, a worldwide survey has been carried out to identify of the most common treatments for cleaning tarnished silver and the personal experience of professionals about the frequency of use, the cleaning efficiency, the surface appearance, the application speed, the difficulty and the applicability. This paper contains the results of this survey. [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]

This work presents the implementation of Visible Hyperspectral Imaging for the in-situ analysis of glass chromophores in two glass windows from the Casa-Museu Dr. Anastácio Gonçalves (Lisbon, Portugal). The measurements were taken inside the building using natural sunlight as the illumination source. In addition, advantages and disadvantages of the followed methodology are discussed. The Dining Room glass window presents glasses colored in bulk with iron, manganese, cobalt, copper, and chromium; silver staining was also detected and was used to create the yellow and orange colors. The Atelier panel was produced with uncolored glasses painted with grisaille and enamels; the chromophores identified are similar to the species identified in the Dining Room panel. Unlabelled Image • Glass chromophores were detected in-situ by Visible Hyperspectral Imaging using sunlight as illumination source. • The technique permitted the overall analysis of each glass of the window in few hours. • Despite the highly optical density of enamels compared to colored glasses, the technique allows the characterization of both. [ABSTRACT FROM AUTHOR]

Highlights • Three types of soda-rich historical fire-polished glasses show different alteration. • Environmental water availability contributes to the increase of the altered layer. • High relative humidity enhances the formation of Na-enriched areas on the surface. • Glass composition has a strong influence on the kinetics of surface alteration. Abstract This paper studied the alteration of three soda-rich-silicate glass types (Cristallo , façon-de-Venise and soda-lime silicate). Replica samples were exposed to different environments simulating museum-like conditions – room temperature and different relative humidities (RH). Results were analysed by SIMS, μ -FTIR, Optical Microscopy and Optical 3D profilometry. Cristallo appears as the most vulnerable, whilst the soda-lime glass appears as the most resistant to the environmental deterioration. The thickness of the altered layer is proportional to the time of exposure and to the RH of the surrounding atmosphere. From the results obtained, the glass composition and the water available and adsorbed to the surface strongly influence the kinetics of the surface alteration. [ABSTRACT FROM AUTHOR]

This paper presents the results derived from an archaeometric study undertaken on glass samples from the Roman town of Augusta Emerita (Mérida, Spain). The main goal of the research was to provide for the first time some compositional and technological insights into the glass finds unearthed in this town. Glass samples from different sites and chronology, either from inside or from outside the perimeter of the ancient town and from the first to the sixth century AD, were analyzed and characterized through optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDS), X-ray fluorescence (XRF) spectrometry and VIS spectrophotometry. Resulting data indicated that all the samples studied were natron-based soda lime silicate glasses, even though two chronological and compositionally distinct groups were distinguished. One composed of Early Empire glasses and a second one composed of glasses from the fourth century AD onward, which was characterized by the presence of the so-called HIMT (high iron, manganese, and titanium) glasses. Comparison with coeval glasses suggested that Augusta Emerita shared the same trade glass circles than other contemporary Roman towns, within the frame of a secondary production scale. Finally, some outstanding differences connected to composition and chronology were found, since Late Roman glasses presented a higher and distinct degree of alteration than Early Empire ones. [ABSTRACT FROM AUTHOR]