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ABSTRACTThe 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.

ABSTRACTStained 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. Grisaillesusually 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 grisaillesare 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 grisaillespresented good durability and stability for use in conservation treatments.

Grisaille was the first paint applied on stained-glass panels, used in Europe since the twelfth century. Historical written sources described the use of iron and copper together with a high lead-silica base glass in the grisailles production. This project aims to study the evolution of the grisaille paint composition throughout time and the changes in the raw materials used in their production using non-destructive and non-invasive techniques. To achieve this objective, 23 grisaille samples dated from the 13th to the twentieth centuries from nine different countries (Portugal, Poland, United Kingdom, Sweden, Norway, Belgium, Low Countries, Germany, and France) were studied by means of micro particle-induced X-ray emission (μ-PIXE), micro energy dispersive X-ray fluorescence (μ-EDXRF), laser-induced breakdown spectroscopy (LIBS), laser-induced fluorescence (LIF), non-linear optical microscopy (NLOM) in the modality of multiphoton excitation fluorescence (MPEF) and optical microscopy (OM). The results showed that it was possible to identify compositional differences and patterns throughout the samples when compared with literature results. The preference for using copper in central and south-central European countries and the addition of new compounds (CoO, Cr2O3, MnO) as colouring agents since the nineteenth century was verified. The LIBS analyses allow the identification of boron on two samples, confirming the change of base glass components since the seventeenth century. The NLOM-MPEF showed the capability of this technique to measure the grisaille paint layers’ thickness. This non-invasive multi-analytical and complementary approach proves itself efficient in identifying changes in the grisaille’s composition throughout time, which can be interpreted as changes in the raw materials and manufacture used in the production of these paint materials.

This work presents an assessment of the different decoration techniques applied in the two glass windows from the Casa-Museu Dr. Anastácio Gonçalves (Lisbon, Portugal) by Optical coherence tomography (OCT). The Dining Room glass window was found to be decorated with grisailles and acid etching, and the Atelierwindow with grisaille, enamel, and cold painting. The alteration state of the surface decorations was also assessed. The thicker surface decorations (grisailles and enamels) presented cracks and detachments, in contrast to the thinner lines which are normally well preserved. OCT is a suitable technique for characterizing glass decoration in situ without dismounting the stained-glass window; and able to reveal the condition and methods of manufacture that cannot be detected simply by visual inspection.

The aim of this work was to determine the physico-chemical characteristics of the stained-glass windows into the 19th century of two mausoleums located in the city of Belém do Pará(Brazil), and to evaluate their state of conservation. The glass chemical composition was determined by WXRF and SEM/EDS. The samples’ morphology and the microorganisms’ identification were carried out by optical microscopy. The results indicated that the samples were soda-lime silicate glass, with approximately 70wt. % of SiO2, which contributed to the resistance of the stained glass to the weathering. The concentration of Na2O was normally twice the K2O, which contrasts with the composition of other panels produced during the same period, as reported in the literature. The biofilm is composed by cyanobacteria and rotifers. Overall, the panels analysed were in a good state of conservation, despite their exposure to tropical climate conditions for more than a century with no preventive measures whatsoever.

The Cathedral of León has one of the most important ensembles of medieval stained glass windows in Europe; however, most of them have been altered by atmospheric weathering. The main objective of this study was the characterization of a set of glass samples from the Cathedral of León, the comparison with glasses from previous interventions in the cathedral and the study of the relation between the alteration pathologies, the chemical composition of the glasses and the environment in which they were placed. The samples were characterized by means of binocular microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry, visible spectrophotometry, X-ray fluorescence spectrometry and X-ray diffraction. The main alteration of glasses exposed until the 19th century was the formation of pits by dealkalinization, while the glasses exposed until the present formed CaSO4deposits as a consequence of the synergic effect of rainwater and gaseous pollutants. Glasses altered by the browning of manganese were also characterized.

The Great Mosque of Córdoba is the only medieval Islamic monument in al-Andalus that still contains some of its original 10th-century glass mosaic decoration, even though they were significantly altered and restored several times in the 18th, 19thand 20thcenturies. By examining analytical, textual, and graphic evidence, this study attempts to reconstruct the different transformations of the Maqṣūrah,focusing on the glass mosaics in order to assess possible implications for their state of preservation. The results show that high-alkaline glass, which can be associated with modern tesserae,was used to restore the Miḥrāband Sābāṭmosaics. Modern pigments were also detected in the paints that were applied in situto the surface of the colourless glasses. Textual and analytical evidences prove that Bāb Bayt al-Mālmosaic was completely removed in the 20thcentury and a replica with high-lead tesseraewas installed in the same place.

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.

This work presents the results of the evaluation of two Art Nouveauglass windows from the Casa-Museu Dr. Anastácio Gonçalves (Lisbon, Portugal) with IR-thermography during the summer solstice. According to the measurements, the surface temperature of glass depended on the outdoor environmental temperature and, mainly, on the direct solar radiation. Colored glasses presented a higher surface temperature due to the absorption of their chromophores at near-IR wavelengths. Enamels and grisailles showed higher surface temperatures than their support glasses due to both their chemical composition and color. The protective glazing, with small slits in one of the window panels, induced a hot-air pocket in its upper part due to the insufficient ventilation.