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Mendes M.T.,National Laboratory for Civil Engineering | Mendes M.T.,University of Evora | Esteves L.,Museu Nacional do Azulejo | Ferreira T.A.,University of Evora | And 5 more authors.
Applied Physics A: Materials Science and Processing | Year: 2016

Knowledge of current conservation materials and methods together with those adopted in the past is essential to aid research and improve or develop better conservation options. The infill and painting of tile lacunae are subjected to special requirements mainly when used in outdoor settings. A selection of the most commonly used materials was undertaken and performed based on inquiries to practitioners working in the field. The infill pastes comprised organic (epoxy, polyester), inorganic (slaked lime, hydraulic lime and zinc hydroxychloride) and mixed organic–inorganic (slaked lime mixed with a vinylic resin) binders. The selected aggregates were those most commonly used or those already present in the commercially formulated products. The infill pastes were characterised by SEM, MIP, open porosity, water absorption by capillarity, water vapour permeability, thermal and hydric expansibilities and adhesion to the ceramic body. Their performance was assessed after curing, artificial ageing (salt ageing and UV–Temp–RH cycles) and natural ageing. The results were interpreted in terms of their significance as indicators of effectiveness, compatibility and durability. © 2016, Springer-Verlag Berlin Heidelberg.

Coentro S.,New University of Lisbon | Coentro S.,Technological and Nuclear Institute of Portugal | Mimoso J.M.,National Laboratory for Civil Engineering | Lima A.M.,New University of Lisbon | And 3 more authors.
Journal of the European Ceramic Society | Year: 2012

A multi-analytical approach was used to study the pictorial layers of a set of 17th century historic glazed tiles (azulejos) of Portuguese manufacture. The pictorial layer was studied by μ-EDXRF, μ-Raman, SEM-EDS and OM. Although the established palette comprises few pigments, it was found that the tiles were enhanced by the use of pigment mixtures, which were identified by μ-Raman and μ-EDXRF. As expected, the blue colour derives from cobalt oxide, purple from manganese oxide and emerald-green from copper oxide. Regarding the yellow pigment, μ-Raman results show it is consistent with the composition of a ternary oxide, whereas μ-EDXRF shows a high intensity of Zn in this colour, indicating a composition close to a Pb-Sb-Zn ternary oxide. Some compounds from the original ores were also indentified: in two very dark blue samples, cobalt and nickel olivines (α-Co2SiO4, α-Ni2SiO4), and in a dark brown sample, braunite (a manganese silicate). © 2011 Elsevier Ltd.

Cabo Verde S.,University of Lisbon | Silva T.,University of Lisbon | Corregidor V.,University of Lisbon | Esteves L.,Museu Nacional do Azulejo | And 6 more authors.
Journal of Materials Science | Year: 2015

The “Great View of Lisbon” is one of the most remarkable blue-and-white Portuguese tile panels, which depicts the city before the tragic earthquake of 1755. This panel presents visible colored alteration in the glaze of tiles both from the exhibition and the depository of the Museu Nacional do Azulejo (Portugal). This work is a contribution to identify the origin of green stains in the glaze by using microbiological techniques, scanning electron microscopy with back-scattered electron imaging (SEM-BSE), Raman spectroscopy, and proton-induced X-ray emission (PIXE). The microbiological assays showed that the filamentous fungi were detected only at a frequency <10 % of the microbiota of tiles surface, and the microbial entities from the green stains cultures were identified as Aspergillus fumigatus by molecular biology techniques. However, no microorganisms or other biological elements were found by SEM-BSE in the green stains. Raman spectroscopy and PIXE results showed that the green stains appear to be related with the presence of chromium atoms in the outer part of the glaze. Eskolaite, a “green pigment” used before 1850 AD was clearly identified by Raman spectroscopy in the darker green stains. Nevertheless, no chromium oxide signatures were identified in the lighter green stains by Raman spectroscopy. © 2015, Springer Science+Business Media New York.

Prudencio M.I.,University of Lisbon | Dias M.I.,University of Lisbon | Burbidge C.I.,University of Lisbon | Kasztovszky Z.,Hungarian Academy of Sciences | And 9 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2016

“The Panoramic View of Lisbon” is a unique masterpiece of Portuguese glazed tiles which depicts the city before the earthquake of 1755. Compositional analysis was done by PGAA, INAA and XRD. The first absolute dating by luminescence was done, including a reconstruction of the history of radiation exposure of the pieces. Compositional patterns of the tiles suggest the use of carbonated clays from downtown Lisbon to manufacture the ceramic bodies at high firing temperatures (900–1100 °C). Luminescence dating results point to the manufacture of “The Panoramic View of Lisbon” in the late 17th–early 18th centuries. © 2015, Akadémiai Kiadó, Budapest, Hungary.

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