Analysis and treatment of a nineteenth century portrait, study of Artsorb® and a proposal for a microclimate frame

The present work is divided in two parts: Part 1 is focused on the analysis and treatment of a 19th century portrait of Domingos Affonso, which belongs to the Ecomuseu Municipal do Seixal; and Part 2, which is entitled “The Microclimate Frame Project” is focused on the study of Artsorb® and on the planning of a microclimate frame for the painting. In Part 1, a study of the painting’s materials was performed using complementary analytical techniques and the painting’s condition was carefully evaluated. The painting exhibited signs of mould growth, and a more detailed investigation was made of this topic to understand if the fungal community was active and if it represented a real danger to the painting. A treatment was proposed, appropriate to the painting’s condition. A description of the treatment carried out, comprising the treatment options, is also present in this section. Within the study of the microclimate frame, in Part 2, the study of the potential corrosiveness of Artsorb® was a central subject. Artsorb® sheets are one of the most widely used materials for buffering relative humidity fluctuations in microclimate frames and its reported excellent performance is enhanced by its availability in lightweight sheets that can be easily placed inside microclimate frames. However, concerns have arisen regarding the presence of the corrosive salt lithium chloride in the composition of this buffer. Consequently, the present work also aimed to understand the potential risks of using Artsorb® and the possibility of avoiding exposure of lithium chloride to the artworks through the use of Tyvek®. Results from the preliminary tests seem to indicate that Artsorb® releases lithium chloride into air. This study also showed that a Tyvek® cover over Artsorb® reduces but does not eliminate evidence of chlorine contamination, and it significantly reduces the effectiveness of the buffering material. Considering that Artsorb® appears to be unsuitable due to the release of the corrosive salt, that Tyvek® was not efficient as a barrier for lithium chloride or as a permeable material to enable the proper functioning of Artsorb®, the buffering material proposed for the use in the microclimate frames is silica gel without indicator. Based on the choice of buffering material, as a result of this study, a microclimate frame is proposed

A policromia da escultura medieval portuguesa em madeira e em pedra: estudo comparativo dos materiais e das técnicas

O trabalho teve como principal objetivo contribuir para o conhecimento mais aprofundado da escultura policromada medieval portuguesa. A escultura policromada desempenhou papel de relevo na sociedade medieval, conservando-se atualmente centenas de exemplares dispersos pelo país. Contudo, o estudo da materialidade destes objetos, e em particular da sua policromia, tem sido negligenciado. A investigação apresentada constituiu o primeiro estudo sistemático dos materiais e das técnicas da policromia da escultura portuguesa dos séculos XIV e XV, estudo comparativo que visou compreender como era aplicada a policromia sobre objetos em pedra e objetos em madeira. De forma a compreender a produção destas esculturas e a enquadrá-la no universo das práticas europeias, a metodologia serviu-se de diversas fontes de informação. A consulta de documentação regimental, notarial, régia e de outras fontes escritas publicadas forneceu indicações acerca dos indivíduos que se encarregavam das diferentes tarefas na produção das esculturas. Foram consultados tratados e receituários artísticos e técnicos medievais, tendo-se identificado e compilado as receitas que versam sobre a aplicação de policromia sobre a madeira e sobre a pedra. Procedeu-se à revisão dos estudos relativos aos materiais e técnicas da policromia da escultura medieval europeia, procurando caracterizar estas práticas, comparando-as com as que têm sido identificadas na policromia destes materiais distintos e identificando tendências, continuidades e desusos. Esta revisão expôs a grande lacuna nos estudos portugueses sobre estes temas. O estudo de caracterização de um grupo de esculturas portuguesas, com uma abordagem multi-analítica, forneceu informações inéditas acerca da policromia original destas esculturas e acerca das práticas portuguesas de produção das policromias. O corpus de esculturas inclui peças em pedra atribuídas às oficinas escultóricas dos mestres Pero, João Afonso e Diogo Pires-o-Velho, e ainda um grupo de esculturas em madeira de autoria desconhecida. Devido à importância destes resultados, e à necessidade de confirmação da data de produção das policromias, testou-se a aplicação da datação por radiocarbono na abordagem multi-analítica. A datação por radiocarbono do pigmento branco de chumbo e do aglutinante orgânico das tintas revelou-se uma ferramenta útil para auxiliar no estudo e na compreensão das complexas estratigrafias das esculturas policromadas. Esta tese traz à luz um conjunto de informações até ao momento desconhecidas, contribuindo para o conhecimento da escultura policromada portuguesa, para compreender a organização do trabalho oficinal da produção destes objetos na Idade Média, e para a contextualização das práticas artísticas portuguesas no universo das práticas europeias.This work aimed to contribute to the deeper knowledge of Portuguese medieval polychrome sculpture. Polychrome sculpture had a significant role in the society of the Middle Ages, and today many objects survive throughout the country. However, the study of these objects’ materiality, and in particular of their polychromy, has been disregarded. This research consists of the first systematic study of the materials and techniques of the polychromy of Portuguese sculpture of the 14th and 15th centuries, a comparative study which envisioned understanding how polychromy was applied to objects on wood and on stone. In order to understand the production of these sculptures and to frame it in the universe of European practices, the defined methodology used various sources of information. The investigation of guild regulations, notarial and royal documentation, and other published written sources provided evidence regarding the professionals who were responsible for the different tasks of the sculptures’ production. Technical and artistic medieval treatises and recipe books were also investigated, and the recipes dealing with the painting of wood and stone supports were identified. A literature review of the materials and techniques of the polychromy of medieval European sculpture was carried out, looking to characterize these practices, compare the materials and techniques which have been identified in the polychromy of such distinct supports, and identify trends, continuing practices and peculiarities. This review confirmed the huge lack of knowledge of Portuguese objects regarding these subjects. The material and technical characterization study of a group of Portuguese polychrome sculptures with a multi-analytical approach provided novel information regarding the original polychromy of these sculptures and of the Portuguese polychrome production practices. The selected corpus of sculptures includes stone objects attributed to the workshops of masters Pero, João Afonso and Diogo Pires-oVelho, and a group of wooden sculptures of unknown authorship. Due to the importance of the results attained and the inherent need of confirming the production dates of the polychromies under study, it was tested the application of radiocarbon dating within the multi-analytical approach used for the study of these polychromies. Radiocarbon dating of the lead white pigment and organic binder of the paint layers proved to be a valuable tool to guide the study and interpretation of the complex paint stratigraphies of the polychrome sculptures. This thesis brings to light an ensemble of information unknown until now, contributing to the deeper knowledge of Portuguese polychrome sculpture, for the understanding of the organization of the workshop labour to produce these objects in the Middle Ages, and to contextualize Portuguese artistic practices within the universe of European practices

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