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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.

This work is focused on the effect of marine aerosols on soda-lime, potash-lime and lead silicate glass samples. Two kinds of tests were carried out, the first one under laboratory controlled condition during 36 days to evaluate the alteration of glass surface by NaCl aerosols, and the second one in a marine atmosphere in Cabo Vilano (Galicia, Spain) for up to three months. Both tests showed similar results. NaCl aerosols acted as condensation nuclei in high humidity environments favoring the lixiviation of the alkaline and alkaline-earth ions from the glass surface and the solubilization of atmospheric gases (CO2, SO2). Marine aerosols could also accelerate the corrosion attack inducing the loss of the surface hydrogen bonds and the opening of the network accelerating the corrosion mechanism. Results also confirmed that high humidity favored the alteration of the glass surface and the formation of new crystalline phases. Soda-lime silicate and lead silicate glasses were the most durable ones, whereas potash-lime silicate glass presented a fissured alteration layer due to the hydrolytic attack of the surface. New crystalline phases including chlorides, carbonates and sulfates were detected on the glass surfaces which can be related to marine aerosols, environmental particles and the reaction of the cations lixiviated from the glass with the atmospheric gases.

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 Article / Artigo II Colóquio Investigações em Conservação do Património II Colloquium Investigations in Heritage ConservationAs grisalhas Debitus para conservação de vitral: um estudo analítico Resumo A grisalha é uma das pinturas vítreas mais antigas e mais usadas na produção de painéis de vitral, e Debitus é uma das marcas comerciais mais conhecidas. As suas grisalhas são frequentemente utilizadas para reintegração cromática em restauro de vitral. Este artigo apresenta a análise química, morfológica e térmica de cinco grisalhas da Debitus, avaliando as suas propriedades antes e depois da cozedura com o objetivo de compreender a sua futura estabilidade. A caracterização foi realizada por microscopia ótica, microscopia eletrónica de varrimento, emissão de raios X induzida por partículas, difração de raios X e termografia de infravermelho. Este estudo demonstrou uma relação equilibrada entre os diferentes componentes e uma boa interdifusão no vidro por parte destes, tal como um comportamento térmico consistente entre eles e com o vidro, o que indica uma boa estabilidade e durabilidade destes materiais. AbstractGrisaille is one of the oldest and most widely used vitreous paint applied for the production of stained-glass panels and Debitus is one of the most renowned commercial brands whose grisailles are frequently used for the chromatic reintegration in stained-glass window restoration. This article presents the morphological, chemical and thermal analyses of five grisailles from Debitus, to evaluate their properties before and after firing with the objective of knowing their future stability. The characterisation was carried out by optical microscopy, scanning electron microscopy, particle induced X-ray emission, X-ray diffraction, and infrared thermography. This study showed a wellbalanced ratio between the different components and a good interdiffusion into the glass, as well as a consistent thermal behaviour between them and with the glass, which indicates the good stability and durability of these materials.

a b s t r a c tTarnishing 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. Different cleaning methods have been used for many years to remove sulphur tarnishing from silver. However, scientific studies which assess the treatment's impact on silver and the re-tarnishing rate are very scarce. Costa [1] carried out a complete bibliographic study about the cleaning procedures and their applications, although the results of these different scientific works are difficult to compare since they have not been systematically evaluated in similar conditions and materials.The aim of this study is to quantitatively assess the efficiency, residues left on the metal and impact on the base metal of eleven mechanical, chemical and electrochemical cleaning methods to remove tarnishing on pure and sterling silver. To evaluate the effect in the long term, several cycles of tarnishing/cleaning are considered.