Historical Stained Glass Painting Techniques Technology and preservation

The aim of this project is the study of the painting techniques applied on stained glass, namely blue enamels, sanguine red and grisaille. The research and interpretation of several historical treatises dated to between the 12th and the 18th centuries was performed, with a study of the production technology of the selected painting techniques, from the preparation of the pigment to the preparation of the paint. With this in mind, selected raw materials used in the productions of blue enamels were characterized, followed by the reproduction of selected historical recipes of blue enamels, sanguine red and grisaille. Parameters such as firing temperature, grinding and binding agents used to apply the paint on glass were considered. The methodology selected was based on the chemical and morphological characterization of both reproduced powder and paint samples by means of a multi-analytical approach. In addition to the reproduction of the selected painting techniques, corrosion studies of blue enamel powder and paint samples were performed in order to provide new insights on the corrosions mechanisms involved. The results obtained were compared with selected painted stained-glass fragments from Portuguese collections, mainly the ones located in Batalha Monastery, Charola from Convento de Cristo in Tomar and Pena National Palace in Sintra. The present study concluded that the choice of the raw materials to the production of the paint, the binder used to apply the paint, and parameters such as firing temperature and heating rate, had an impact on the outcome, resulting on a better adhesion of the paint layer to the base glass. The use of zaffer as a colouring agent does not allow determination of the outcome of the paint, while adding powdered glass such as smalt gives to the glass painter the opportunity to know the final result before firing. As for sanguine red paint, it is concluded that the final outcome of the paint is strongly influenced by the heating rate. In addition, the use of gum arabic as a binder, or in the pigment itself, provides a better adhesion of the paint layer to the base glass. Regarding the grisaille painting, the main differences between the recipes lay on the composition of the lead-based glass and on the ratios between this and the colouring agents. Furthermore, it was also possible to conclude that there is an evolution of the morphology of the grisailles towards a higher homogeneity of the surface. The corrosion studies performed on blue enamels allowed to conclude that with the lixiviation of the alkaline components of the enamel, cobalt will be influenced by other neighbouring ions, leading to a change of colour. In some cases, Pb2+ ions may also be the responsible for this colour change, with the formation of lead white. The results obtained were in a good agreement with the characterization of the selected case studies, evidencing the importance of the intersection between the written sources and the laboratory work

Estudo de um vitral quatrocentista do Mosteiro de Santa Maria da Vitória, Batalha: caracterização, fenómenos de degradação e processos de limpeza com Líquidos Iónicos

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro - Especialização em VitralO Mosteiro de Santa Maria da Vitória na Batalha apresenta um espólio emblemático da arte do vitral português, uma actividade realizada em pleno nos séculos XV e XVI, sendo o Mosteiro o principal estaleiro. O presente trabalho teve como objectivo a caracterização histórica e material do painel S07c, intitulado “Figura aureolada”, que se encontra actualmente no Núcleo do Departamento de Conservação e Restauro da FCT/UNL. É apresentada uma proposta de reconstituição de um painel à escala, tendo em conta os diversos fragmentos dos painéis quatrocentistas do Mosteiro da Batalha e exemplos coevos que se encontram na Alemanha, na época o Sacro Império Romano Germânico. Foi também estudada a eficácia de utilização de Líquidos Iónicos como novos materiais alternativos aos métodos de limpeza convencionais. Para melhor caracterização e análise das experiências efectuadas recorreram-se a determinadas técnicas analíticas, entre as quais a Microscopia Óptica (MO), a Microfluorescência de Raios-X Dispersiva de Energia (EDXRF), Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), Espectroscopia Raman, Espectroscopia Electrónica de Varrimento (SEM) e Espectroscopia de Emissão Atómica por Indução Eléctrica de Plasma (ICP-AES). Os ensaios efectuados revelaram que os Líquidos Iónicos apresentam-se como uma alternativa aos métodos actuais de limpeza de vitrais, revelando boas propriedades na remoção de crostas de corrosão

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved