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Abstract Urban and industrial atmospheres can produce several damages on glass façades and historical stained-glass windows; however, the effect of coastal atmosphere on them has been scarcely studied. This work presents the results of the exposure of soda-lime, potash-lime, and mixed-alkali silicate glass to the coastal atmosphere in Cape Vilán (Galicia, Spain) at different distances to the coast (inland) during twelve months. Crystalline deposits were observed on all the samples, although their quantity depended on the meteorological conditions. The samples located nearest to the coast presented alteration layers, while those ones located farthest from the shore presented several isolated pits. Regarding the chemical composition, potash-lime silicate glass, typical composition from medieval glass windows, was the most altered glass in contrast to soda-lime and mixed-alkali silicate glasses. Graphical abstract Image 1 Highlights • The glass alteration depended on the distance to the coast. • The glasses exposed near the coast presented alteration layers on their surface. • The glasses exposed far from the shore presented isolated pits. • Potash-lime silicate glass was the most altered glass. [ABSTRACT FROM AUTHOR]

Lead has a good resistance to atmospheric corrosion because it forms adherent, uniform and protective layers which prevent the corrosion advancement. Nevertheless, the exposure to the acetic and formic acids – emitted by wood and other materials used in museums’ showcases, cabinets and storehouses – induces a corrosion process which can damage the surface of the objects. In order to improve their conservation, restorers apply different conservation treatments which depends on the degree of corrosion, the products formed, the skills of the conservator and the access to specific equipment, if is required. With the aim of evaluating the impact of successive conservation treatments on lead surface and assessing their efficiency, four usual treatments for lead were selected and six cycles of alteration and treatment were carried out. The assessed procedures were mechanical cleaning (suspension of CaCO 3 ), chemical cleaning (immersion on EDTA solution) and two electrochemical treatments (potentiostatic reduction, and potentiostatic reduction followed by passivation). The samples were characterized before and after each treatment with gravimetry, colorimetry, rugosimetry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The effects observed on lead coupons depended on each treatment procedure. The mechanical cleaning with CaCO 3 produced a significant mass loss and it left an irregular surface due to the granulometry of the abrasive. Additionally, it experienced a fast re-alteration. Chemical cleaning with EDTA produced moderate mass and gloss losses due to the etching of the metallic surface after successive cycles. However, the color of the samples was the closest to the original one. Finally, the electrochemical reductions produced a scarce mass loss and a slow re-alteration, although they produced crystalline deposits on the surface which modified the color of the coupons towards bluish hues. [ABSTRACT FROM AUTHOR]

Tarnishing is produced by reaction of silver with gaseous reduced sulphur compounds from atmospheric pollution. It induces the formation of Ag 2 S crystals which produce a dark appearance. To remove sulphur tarnishing, different mechanical, chemical and electrochemical methods have been traditionally used. To assess the effect of different cleaning treatments on tarnished silver, coupons of pure and sterling silver (92% Ag/8% Cu) were subjected to six cycles of induced tarnishing and cleaning. The cleaning methods evaluated were mechanical (soft abrasives and rubber point mounted on a rotary tool); chemical (chelating and acid solutions) and electrochemical (potentiostatic reductions). Surface morphology, composition, weight, color and luminosity were evaluated by optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and colorimetry. The cleaning impact on tarnished silver depended on the cleaning procedure and the composition of silver. Mechanical treatments restored the original visual appearance of silver although they produced a significant mass loss and a fast re-tarnishing. Chemical cleaning methods were fast; nevertheless the surface appeared completely attacked. Electrochemical cleaning did not yield good result for sterling silver, but was an effective cleaning method for pure silver coupons. [ABSTRACT FROM AUTHOR]

Crizzling is an alteration pathology of non-equilibrated glasses that can produce a fast surface alteration. The Royal Palace of Madrid and the Technological Museum of Glass (Segovia) preserved pieces with incipient crizzling produced by the Spanish Royal Glass Factory in the first decades of the 19th century. The objective of this study was to assess the environmental conditions in both collections to enhance their preservation conditions and to identify possible pollutants that can accelerate their alteration. Both collections presented suitable thermohygrometric conditions for general collection; however, it was observed that illumination induces humidity fluctuations inside the cabinets. Passive samplers detected a high concentration of formic acid in some locations, mainly related to the presence of wood furniture. In these locations, glass pieces showed a high surface hygroscopicity (pH 8) and a high concentration of K+- and COOH− ions. • The indoor environments of Royal Palace of Madrid and the Technological Museum of Glass were assessed. • The cabinets' illumination induced daily fluctuations of temperature and humidity. • The most aggressive environments were detected inside wooden wardrobes. • Higher was the concentration of formic acid, faster was the alteration of non-equilibrated glasses. [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]

• Literature from 1984 to 2020 regarding grisaille is reviewed. • The spatio-temporal study reflects changes in grisailles composition. • The iron oxide is the main colouring agent identified throughout the centuries. • In Germany, Italy and Czech Republic the copper oxide is in higher proportion. • The main substrate glasses identified are sodium-rich and potassium-rich glasses. This work presents the first review on the characterisation of grisaille stained-glass paint, in order to follow the evolution of the production materials and methods throughout time and provenance. From the literature review, 38 scientific studies regarding the grisaille paint were found, dated between 1984 and 2020. In these works, various samples from the 13th to the 20th centuries belonging to 11 different European countries were characterised. In general, iron oxide was the main colouring agent identified throughout the centuries and countries, except in the Central and South-Central European countries where copper oxide was preferably used. Different metal oxides, such as cobalt, chromium and manganese were also identified in modern samples (19th and 20th centuries), used together with iron oxides. The base glasses generally presented a lower ratio PbO:SiO 2 (~0.5 to 1) than the expected from the historical recipes, and the addition of borax is suggested for grisailles from the 17th century onwards. The proportion between the base glass and colouring agents showed ratios between 1 and 1.5, related to well-balanced grisailles. The present overview, critical analysis and comparison of published studies regarding this glass-based paint allow to draw a spatio-temporal map of the grisaille composition evolution, which reflects the changes in composition regarding the country of provenance and century. [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]