Comparative Study of Four Portuguese 16th Century Illuminated Manueline Charters based on Spectroscopy and Chemometrics Analysis

The comparative study based on spectroscopic analysis of the materials used to produce four sixteenth-century Manueline Charters (the Charters of Alcochete, Terena, Alandroal and Evora) was performed following a systematic analytical approach. SEM–EDS, l-Raman and l-FTIR analysis highlighted interesting features between them, namely the use of different pigments and colourants (such as different green and yellow pigments), the presence of pigments alterations and the use of a non-expected extemporaneous material (with the presence of titanium white in the Charter of Alcochete). Principal component analysis restricted to the C–H absorption region (3000–2840 cm-1) was applied to 36 infrared spectra of blue historical samples from the Charters of Alcochete,Terena, Alandroal and Évora, suggesting the use of a mixture of a triglyceride and polysaccharide as binder.

God is in the detail. Gold, silver and polychromy

The visible polychromy of a wooden sculpture representing St. John the Evangelist, from Museu Nacional de Arte Antiga, Lisbon (Portugal) presents several techniques that complement each other on the creation of a sumptuous estofado. This case-study allowed the survey on gilding, silvering and polychromy practices, and observations on their execution are briefly reported and documented with results from a multi-analytical approach. Examination included digital photomicrography and the observation of micro-samples cross-sections, while material identification resorted to several analytical methods that included scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD).

MATERIAL CHARACTERIZATION OF GILDING AND PAINTING TECHNIQUES OF A POST-BYZANTINE ICON

This study aims to identify the materials used in the production of a post-byzantine icon from the Museum of Évora’s collection. The icon, representing the “Emperor Constantine and his mother Helen holding the Holy Cross” was once dated as being from the 10th century. Throughout a multi-analytical approach, combining area exams with spectroscopic techniques, this study tried to confirm its actual chronology. The results obtained revealed that it is most likely an icon from the late 17th or 18th century.

Characterization of the glaze and in-glaze pigments of the nineteenth-century relief tiles from the Pena National Palace, Sintra, Portugal

The glaze and in-glaze pigments of the historical nineteenth-century glazed tiles from the Pena National Palace (Sintra, Portugal) were characterized using a multi-analytical approach. Chemical composition and microstructural characterization were ascertained by µ-PIXE, µ-Raman, optical microscopy and VP-SEM–EDS. The manufacturing technique and colour palette in these tiles were found to be close to the ceramic pigments used in traditional majolica. The blue and purple colours derive from cobalt oxide and manganese oxide, respectively. A mixture of Pb–Sn–Sb yellow with cobalt oxide and iron oxide was used for green and dark yellow, respectively, while grey tonalities consist of a complex mixture of cobalt oxide, manganese oxide and Pb–Sn–Sb yellow in different proportions. Results obtained allowed the determination of the oxides and elements used in pigments as well as production techniques, resorting to traditional majolica manufacture, although the tiles were produced by the end of the nineteenth century.

New insight on the underdrawing of 16th Flemish-Portuguese easel paintings by combined surface analysis and microanalytical techniques

This paper focusses on the study of the underdrawings of 16th century easel paintings attributed to the workshop of the Portuguese-Flemish Master Frei Carlos. This investigation encompasses multidisciplinary research that relates the results of surface exams (infrared reflectography, standard light photography and infrared photography) with analytical investigations. The surface analysis of Frei Carlos’ underdrawings by infrared reflectography has shown heterogeneous work, revealing two different situations: (1) an abundant and expressive underdrawing, revealing a Flemish influence and (2) a simple and outlined underdrawing. This preliminary research raised an important question related to this Portuguese-Flemish workshop and to the analytical approach: Is the underdrawing's heterogeneity, as observed in the reflectograms, related to different artists or is this rather an effect that is produced due to the use of different materials in the underdrawing's execution? Consequently, if different materials were used, how can we have access to the hidden underdrawings? In order to understand the reasons for this dissemblance, chemical analysis of micro-samples collected in underdrawing areas and representing both situations were carried out by optical microscopy, micro Fourier transform infrared spectroscopy (μ-FTIR), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX) and micro-Raman spectroscopy (μ-Raman). Taking into account the different possibilities and practical and theoretical limitations of surface and punctual examinations in the study of easel painting underdrawings, the methodology of research was adjusted, sometimes resulting in a re-analysis of experimental results. This research shows the importance of combining multispectral surface exams and chemical analysis in the understanding of the artistic creative processes of 16th century easel paintings.

Technological characterization of molded islamic pottery from Iberian Peninsula

The thesis examines the technical aspects of unglazed molded ceramics from Mértola, in the context of Islamic archaeology of the Iberian Peninsula (Almohad period, end of 12th and the beginning of 13th century). Ceramics of the time period under discussion (12th – 13th century) are understudied, including in what concern to shaping and firing of ceramic vessels, the origin of raw materials used in ceramics and glazes, and decoration methods such as slip painting and/or colored glazes. Moreover, the use of archaeometry tools is rare. Along with providing a general picture of molded ceramic production in Mértola, this work provides a new dimension to the discipline of Islamic ceramic studies by the analytical tool used and demonstrating the importance of archaeological ceramics of the western peripheries to the understanding the production of ceramics and the transmission of knowledge and cultural traditions within the Islamic caliphate. The chemical and mineralogical characterization of 12th/13th century Almohad unglazed molded ware from Mértola was accomplished through multi – analytical approach combining SEM, Powder/uXRD and LA-ICP-MS methods. In this paper unglazed and glazed samples were analyzed but the attention was given to unglazed specimens, while the glazed samples were used for the comparison with the previous group in order to determine possible similarities or dissimilarities, thus providing enough data to discuss about technical aspects and potential provenance; Resumo: A tese debruça-se sobre os aspetos técnicos de cerâmica de molde não-vidrada de Mértola, no contexto da arqueologia islâmica da Península Ibérica (período Almóada, final de XII e início do século XIII). A cerâmica do período em discussão (séculos XII-XIII) é pouco estudada inclusive no que concerne ao fabrico e à cozedura, à de fonte de matérias-primas, na pasta ou nos esmaltes e aos métodos de decoração, como pintura, presença de engobes ou esmaltes. Além disso, o uso de ferramentas de Arqueometria é raro. Para fornecer uma visão geral da produção de cerâmica moldada em Mértola, este trabalho oferece uma nova dimensão para a disciplina de cerâmica islâmicas pelas ferramentas analíticas utilizadas. Demonstrando a importância da cerâmica arqueológica da periferia ocidental para a compreensão da produção cerâmica e a transmissão de conhecimentos e tradições culturais no califado islâmico. A caracterização mineralógica e química das cerâmicas de molde e não-vidrada, Almóada, dos séculos XII-XIII de Mértola foi realizada através de uma abordagem multi-analítica que combina métodos de SEM-EDS, uXRD e LA-ICP-MS. Neste trabalho, as cerâmicas vidradas e não-vidradas foram analisadas conjuntamente, dando mais atenção aos espécimes não vidrados. As amostras de cerâmicas vidradas foram utilizados para a comparação com o grupo anterior, a fim de determinar as possíveis semelhanças ou diferenças, proporcionando, assim, dados suficientes para discutir os aspetos técnicos e o potencial de proveniência das cerâmicas não vidradas