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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]

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]

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]

• K 2 O-PbO-(CaO)-SiO 2 glasses were altered in atmospheres enriched in formic acid. • Higher was the concentration of formic acid, faster was the alteration. • The addition of stabilizers to the glass slowed down the alteration rate. • For the same molar concentration, calcium was better stabilizer than lead. George Ravenscroft designed the lead silicate glasses in 17th-century; however, the first pieces produced showed degradation pathologies after few years. This study reproduces one of the glasses produced by George Ravenscroft and analyses its chemical stability in comparison to two other glasses based on the original composition but with the addition of 5 mol % of PbO and CaO, respectively. The three glasses were exposed to an environment of high humidity and different concentrations of formic acid (0, 100 and 300 ppm), which is the main contaminant in display cases and wooden cabinets. The hygroscopic capacity of the glass was analysed by gravimetry, infrared spectroscopy and µ-Raman spectroscopy. The results show that the acidic environment promotes the ion exchange reaction, accelerating the leaching of alkaline ions, which has a great influence on the durability of the glass. The glasses with a higher content of stabilizers presented a greater stability, especially the glass with calcium. [Display omitted] [ABSTRACT FROM AUTHOR]