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Projeto de investigação
From the texts to the laboratory - a study for the preservation of hostorical grisailles
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An Overview of Germanic Grisailles through the Stained-Glass Collection at Pena Palace
Publication . Rodrigues, Alexandra; Coutinho, Mathilda L.; Machado, Carla; Alves, Luís Cerqueira; Machado, Andreia; Vilarigues, Márcia; VICARTE - Vidro e Cerâmica para as Artes; DCR - Departamento de Conservação e Restauro; MDPI - Multidisciplinary Digital Publishing Institute
The lack of studies reporting the characterisation of Germanic grisaille is evident, despite the recent interest of researchers in this glass painting material. This work consists of the first assessment of Germanic grisaille’ chemical composition on a wide chronology (14th–19th centuries), that was only possible through the unique stained-glass collection of King Ferdinand II of Portugal. From the considerable amount of panels produced in Germanic territory and assembled by Ferdinand, twenty-two panels were characterised, and some trends of glass support typical composition and grisaille recipes were verified through this case study. A copper-based grisaille appears to have been the preference up to the 18th century. The 19th century shows higher diversity in composition, with new compounds (such as Co, Cr, Mn) appearing as colourising materials. However, with a limited number of analyses, and dispersed throughout time and different geographic locations, the results of this study are unprecedented, by being able to present the first overview on grisaille composition in Germanic stained glasses.
The Influence of Raw Materials on the Stability of Grisaille Paint Layers
Publication . Machado, Carla; Vilarigues, Márcia; Pinto, Joana Vaz; Palomar, Teresa; DCR - Departamento de Conservação e Restauro; VICARTE - Vidro e Cerâmica para as Artes; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; MDPI - Multidisciplinary Digital Publishing Institute
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.
Laser-based techniques for the non-invasive characterisation of grisaille paints on stained-glass windows
Publication . Machado, Carla; Oujja, Mohamed; Cerqueira Alves, Luís; Martínez-Weinbaum, Marina; Maestro-Guijarro, Laura; Carmona-Quiroga, Paula María; Castillejo, Marta; Vilarigues, Márcia; Palomar, Teresa; DCR - Departamento de Conservação e Restauro; VICARTE - Vidro e Cerâmica para as Artes; SpringerOpen
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.
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Fundação para a Ciência e a Tecnologia
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Número da atribuição
PD/BD/136673/2018