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HERCULES Laboratory - Cultural Heritage, Studies and Safeguard
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Study of historical mortars from the Roman Villa of Frielas (Loures, Portugal)
Publication . Ahmmed, T.; Galacho, C.; Silva, A. R.; Quaresma, J.; Moita, P.; CHAM - Centro de Humanidades; Departamento de História (DH)
The Roman villa of Frielas is an archaeological site from 3rd – 6th century AD located in Loures, Portugal. The villa is on excavation since 1997. A total of eighteen mortar samples were collected from the different structures of the villa with different functional uses (render, filler, and floor) and analyzed by a multi-analytical approach. The results revealed a similar composition of binder, while differences in aggregates allowed to establish several groups. The information was analyzed to understand if historic recipes from ancient Roman treatises as described by Vitruvius were followed in the manufacturing process, or if traditional formulae were adjusted and adapted to meet a specific demand or due to resource constraints.
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.
Underneath the Purple Stain
Publication . Pinheiro, Catarina; Miller, Ana Zélia; Vaz, Patrícia; Caldeira, Ana Teresa; Casanova, Conceição; DCR - Departamento de Conservação e Restauro; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
The Alcobacenses are one of the most important Portuguese collections of Monastic codices. During a campaign study to further advance our knowledge on this important legacy and its state of conservation, a heavily deteriorated codex (ALC.338) stood out due to the presence of purple stains on the lower margins on virtually all folios. In some of them, the purple stains are accompanied by yellow and brown patches as well. Also noticed was the presence of these purple spots on the white tawed leather covering the codex. The codex was analyzed macro and microscopically, chemically and biologically using state-of-the-art technology such as next-generation sequencing. The biological deterioration associated with the appearance of these purple spots arises from the inside out and reveals significant abundance of the bacterial genus Saccharopolyspora sp., which accounted for 86% of the bacterial genera identified. For the fungal population, the most common genus was Malassezia sp. Visual inspection of the sample confirmed the presence of fungal and bacterial biofilms. Pressing questions, comparison to similar studies and future perspectives are also given.
Study of a late bronze age casting mould and its black residue by 3D imaging, pXRF, SEM-EDS, micro-FTIR and micro-raman
Publication . Figueiredo, Elin; Bottaini, Carlo; Miguel, Catarina; Lackinger, Aaron; Mirão, José; Rey, Beatriz Comendador; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MDPI - Multidisciplinary Digital Publishing Institute
In the present work, a fragment of a stone mould recently found in Galicia (NW Spain) was studied by multiple analytical techniques approach involving 3D optical imaging reconstruction to obtain data about the shape of the mould, typology of artefact produced, and distribution of a black residue at the surface of the mould and pXRF, SEM-EDS, micro-FTIR, and micro-Raman to investigate the nature of the black residue. The study shows that the mould was likely used for socketed axes with a side loop, was originally composed of two valves and one core, and that it might have been subjected to a repair during use. The black residue is distributed in the carved surface and spreads to nearby surfaces as a result of the use of the mould. The alloy cast in the mould was a ternary bronze (Cu + Sn + Pb). The analyses by SEM-EDS of black residue covering the surface did show the presence of scattered micro particles with P and Ca, and micro-Raman analysis detected the presence of a carbon black of animal source, while micro-FTIR analysis detected remains of proteins, oxalates, and hydroxyapatite. These results are amongst the very few studies made on black residues of ancient moulds and suggest that the mould was dressed with a carbon black of animal origin, such as burned bones, prior to metal casting, probably used as a coating agent to improve the casting and artefact recovery.
Contribution to the Understanding of the Colour Change in Bluish-Grey Limestones
Publication . Silva, Teresa P.; de Oliveira, Daniel P. S.; Veiga, João P.; Lisboa, Vitor; Carvalho, Jorge; Barreiros, M. Alexandra; Coutinho, Mathilda L.; Salas-Colera, Eduardo; Vigário, Rogério; DCR - Departamento de Conservação e Restauro; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); VICARTE - Vidro e Cerâmica para as Artes; MDPI - Multidisciplinary Digital Publishing Institute
Bluish-grey limestones have been extensively used as ornamental stones for decoration purposes in buildings, as well as in works of art, and accordingly, have been the target of intense exploration. In Portugal, the Jurassic limestone massif known as the Maciço Calcário Estremenho (MCE), has been the source of grey-coloured ornamental stones, namely the Azul Valverde (one of the most well-known bluish-grey limestones) and Atlantic Blue varieties, both of which may undergo colour changes in outdoor environments. In this sense, it is important to understand the sudden colour change from bluish-grey to yellow/beige in the same limestone block in a quarry, or even, what happens to the colour when polished limestone is placed outdoors. This study was undertaken using various techniques, namely XRF (X-ray fluorescence spectrometry), XRD (X-ray diffraction), SEM (scanning electron microscopy), DTA–TG (differential thermal analysis/thermogra-vimetry) and colourimetry. Synchrotron radiation was also used at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) where XANES (X-ray Absorption Near Edge Structure) spectra at Fe K-edge were collected to ascertain the speciation state of Fe in different coloured zones of the limestone, previously checked by EDXRF (energy dispersive X-ray fluorescence). The presence of Fe2+ and Fe3+ are responsible for the greyish and yellow/brown colour, respectively. On the other hand, the UV radiation from the sun causes a quickened and severe bleaching/fading on the dark blue/grey polished limestone.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDP/04449/2020