Azulejos Research Articles

Filling and retouching techniques in outdoor tiles with saline efflorescence problems. A case study

This article will be focusing on a retouching conservation and restoration treatment, of two figurative ceramic tiles panels belonging to the Baroque artistic period. The ceramic tiles of blue and white colors dating from the final of the 18th century are inserted in a relevant historical period for the Portuguese tiles art entitled Grande produção Joanina. The purpose of the intervention was the return the readability of the scenes in the panels, without hiding major signs of degradation. This conservation treatment was made within a rehabilitation project of the building that holds them, which had its own intervention criteria and in which the conservation criteria had to fit. One of the issues during this case study, was to find a commitment between the conservation ethical approaches, considering the panels will continue to be exposed outdoors and there are soluble salts present on the wall where they are settled. The intervention criteria chosen was made, using diverse solutions within materials and techniques such as the application of new ceramic elements, filling gaps with lime mortars and al fresco retouching. A capillarity and permeability based method was used to fill the glazed gaps. Retouching methods were tested including neutral tone or continuing the shapes and tones. In the end al fresco retouching method was chosen and the preparation of the new ceramic elements supported by a study of graphic and photographic documentation, completing the big gaps in the panels. The results of the chosen al fresco technique show a satisfactory level of mimicry, enough to return the readability of the panel. This technique revealed to be suitable for the retouching of ceramic substrates affected by soluble salts. The reading of the scene panels became passively also, by completion the missing parts, with the introduction of new elements what, was achieved with success too.

Editorial

Editorial

Urban Geodiversity and Decorative Arts: the Curious Case of the “Rudist Tiles” of Lisbon (Portugal)

One key element defining the appearance of Lisbon is the whitish Cretaceous fossiliferous limestone locally known as “lios.” The lios is abundantly used as ornamental stone in Lisbon’s monuments and buildings. Ceramic tiles are also paramount in creating Lisbon’s character. Their ubiquitous presence, their colourful patterns and even the unique way they reflect sunlight make them inextricable from the city’s ambiance. In nineteenth century tiles, the urge to emulate lios—a noble and expensive building material—in building facades led to the use of the trompe l’oeil technique to mimic the appearance of the stone. The representation of the fossiliferous lios pattern is so realistic that Radiolitid and Caprinid rudists may easily be identified. At present, “rudist tiles” are not recognized as such by decorative arts experts. These tile panels are commonly seen as lesser productions depicting indistinct “marbled” patterns and often ignored or even discarded. This novel interpretation of rudist tiles leads to the clear recognition of the lios—a typical element of local geodiversity—depicted in them, thus revealing their uniqueness and close connection with the geodiversity and the cultural ambiance of Lisbon. Hopefully, this will boost the geoawareness of the public and art experts alike, making the need for the geoconservation of the lios and its palaeontological record and the preservation of these tiles as cultural heritage all the more obvious. This example of the influence of geodiversity in the creation of artistic concepts and representations and, consequently, in the shaping of the cultural landscape of Lisbon is all the more important now that the application of Portuguese tiles for inclusion on the UNESCO World Heritage List is being prepared.

Hot restoration technologies for external coating tiles: Nossa Senhora da Soledade Cemetery (Belém, Brazil)

In Belem, Brazil, during the 19th century, Portuguese tiles were used for the external facing of sepultures at the Soledade Cemetery. These pieces are fragile because of exposure to the tropical climate and of their location close to the ground. This research aims to obtain subsidies for the restoration of the glazed layer, through hot restoration, to serve as theoretical and technological references for future restoration projects. The samples consisted of fragments of Portuguese historical tiles from the Soledade Cemetery. Restoration was performed by cleaning (both mechanical and chemical ways) and re-firing (1000oC). Before and after the re-firing, samples were submitted to the analytical technique of X-ray diffraction. The results indicate that the re-firing eliminated defects and pathologies existent in the glaze and caused changes in the mineralogical composition of the ceramics. Used carefully, the hot technique is one of the alternatives to improve durability and protect the Soledade historical tiles.

Os azulejos da Misericórdia: a imagem documento na história da cultura religiosa luso-brasileira

Os azulejos portugueses em Portugal e no Brasil são considerados quase sempre como objetos da História da Arte. A proposta deste estudo consiste em abordar os azulejos não como objetos de arte, mas como documentos da história da cultura luso-brasileira. O conceito de imagem documento será desenvolvido por meio da análise de um dos ritos mais importantes da história da cultura religiosa ocidental: a procissão. A atenção do estudo recairá, em especial, sobre a Procissão dos Ossos, que se encontra representada nos painéis de azulejos (séc. XVIII) da Igreja da Misericórdia em Salvador. A Procissão dos Ossos, instituída por D. Manoel em 1498, tinha como objetivo a retirada dos ossos dos justiçados, dando-lhes sepultura. Para a missão, o rei designou a Ordem da Misericórdia. O ato régio se estendeu ao Brasil, quando a primeira Casa da Misericórdia foi fundada na cidade do Salvador, em 1549. O painel, datado do século XVIII, representando a cerimônia, divide o espaço da igreja da Misericórdia com outras duas representações: a procissão do Senhor Morto, introduzida no Brasil (também pelos portugueses), e a Procissão do Fogaréu, introduzida pelos espanhóis. Entre a data da realização da primeira Procissão dos Ossos e o assentamento do painel de azulejos existe um espaço de tempo que permite avaliar a heterogeneidade dos tempos da arte, onde os ritmos diferenciados não coincidem, necessariamente, com os tempos da história.

Electrochemical desalination of historic Portuguese tiles – Removal of chlorides, nitrates and sulfates

Abstract Soluble salts cause severe decay of historic Portuguese tiles. Treatment options for removal of the salts to stop the decay are few. The present paper deals with development of a method for electrochemical desalination, where an electric DC field is applied to the tiles. Laboratory experiments were conducted with single 18th century tiles from Palacio Centeno, Lisbon, Portugal. Large parts of the glaze and parts of the biscuit were lost from salt decay. The major aim of the investigation was to see if the method could offer sufficient salt removal in the biscuit and in the interface between biscuit and glaze, where salt crystals were clearly identified by SEM-EDX before desalination. The concentrations of chloride and especially nitrate were very high in the tiles (around 280 mmol Cl − /kg and 450 mmol NO 3 − /kg respectively). Both anions were successfully removed to below 6 mmol/kg during the electrochemical treatment. The removal rate was similar for the two anions so the chloride concentration reached the lowest concentration level first. At this point the electric resistance increased, but the removal of nitrate continued unaffected till similar low concentration. The sulfate concentration was initially very low, but nevertheless, sulfate removal started at the point where chloride and nitrate concentrations were very low in the tiles. Investigating the interface between biscuit and glaze after the treatment showed no signs of crystallized salts, so also in this important point, the desalination was successful. Based on the obtained results an important step is taken towards development of an electrochemical technique for desalination of tile panels.

The mineralogy and chemistry of the German and Portuguese tiles used to face a historic building in the Amazon region and their natural susceptibility to tropical weathering

During the 19th century, the most prominent buildings of the city of Belém were faced entirely with tiles manufactured in Portugal and Germany, which now exhibit distinct degrees of degradation. The Pinho mansion is one of the most important of these buildings and was selected for the investigation of the action of the tropical Amazonian climate on the degradation of the tiles. To achieve this objective, the tiles were mapped for organic and inorganic degradation, and samples were collected for analysis. The minerals were determined by XRD, the chemical composition by classical wet methods and SEM/EDS, and the microorganisms under the microscope. The results show that the German and Portuguese tiles are quite different in their composition. While both ceramic bodies are composed of SiO2 and Al2O3, CaO was found only in the Portuguese tile. The low Na2O and K2O contents indicate the addition of materials to reduce the fusion temperature. SiO2 and PbO are the main constituents of the glaze, with CoO and FeO being added as pigment. The ceramic body of the German tiles is constituted of quartz, mullite, and cristobalite, in contrast with the Portuguese tiles, which are made of quartz, gehlenite, diopside, calcite, and feldspars. The glazes are XRD-amorphous. The chemical and mineralogical differences between the German and Portuguese tiles indicate that they were produced from different raw materials under distinct thermal processes. The most prominent weathering-related modifications are the thin layers (German tiles), oxidation stains, dark stains, the detachment of the tile (Portuguese tiles), loss of the glaze and powdering of the ceramic body (Portuguese tiles) through the establishment of Cyanophyta and Bacillariophyta.. The distinct degradation patterns of the tiles exposed to the tropical Amazon climate are a consequence of their distinct mineralogy and chemistry.

Micro-XRF for characterization of Moroccan glazed ceramics and Portuguese tiles

A set of enamelled terracotta samples (Zellij) collected from five different monuments in Morocco were object of study. With the aim of characterizing these typically Moroccan artistic objects, X-ray spectroscopic techniques were used as analytical tool to provide elemental and compound information. A lack of information about these types of artistic ceramics is found by the research through international scientific journals, so this investigation is an opportunity to fulfill this gap. For this purpose, micro-Energy Dispersive X-ray Fluorescence (μ-EDXRF), and wavelength dispersive X-ray Fluorescence (WDXRF) and X-ray Diffraction (XRD) were the chosen methods. As complementary information, a comparison with other sort of artistic pottery objects is given, more precisely with Portuguese glazed wall tiles (Azulejos), based in the Islamic pottery traditions. Differences between these two types of decorative pottery were found and presented in this manuscript.

Resources for Latin American art in the Gulbenkian Art Library

From its creation in 1968 the Gulbenkian Art Library has possessed a number of special collections, and these have been enriched through major bequests or through acquisition. Currently there are about 180 collections with relevance for the study of Portuguese art and culture: they include private libraries, the private archives of Portuguese artists and architects, and photographic archives. Material in the special collections is available through the library’s catalogue and some have already been digitised and are available on the internet, depending on their copyright terms and conditions. Among these special collections two have special relevance to the study of the history of Brazilian art and architecture: the collection of Portuguese tiles and the Robert Smith Collection.

A colecção fotográfica "Inventário da Azulejaria Portuguesa" de João Miguel Santos Simões (1960-1968): objecto artístico, documento e memória

O "Inventário da Azulejaria Portuguesa" é um conjunto de espécies fotográficas coladas em cartão. Composta por 5028 documentos fotográficos ( a p& b e a cores), esta colecção faz parte de um projecto mais abrangente e ambicioso proposto pelo estudioso da Azulejaria Portuguesa João Miguel Santos Simões (1907-1972) à Fundação Calouste Gulbenkian em Lisboa no ano de 1958, de que resultaram a criação da Brigada de Estudos da Azulejaria e o Corpus da Azulejaria Portuguesa que a Fundação Calouste Gulbenkian editou entre 1963 e 1970. Cobrindo um vastíssimo território geográfico continental e atlântico, este espólio fotográfico - desde 2005 digitalizado e disponível online a partir da pesquisa do catálogo da Biblioteca de Arte da FGC - reverte-se de um importante interesse como documento histórico no estudo e levantamento do Património em Azulejo ainda existente e parte desaparecido. O propósito deste texto é apresentar e validar a importância enquanto memória documental desta mesma colecção, no âmbito de uma estrutura de organização mais vasta, como foi o rastreio sistemático e a recolha de elementos informativos e actualizados no tempo sobre a azulejaria portuguesa.

Effect of the impregnation treatment with Paraloid B-72 on the properties of old Portuguese ceramic tiles

In this work, the effect of the impregnation with Paraloid B-72, using the protocol commonly followed in museum restoration departments, on the mechanical and water absorption properties of Portuguese tiles from XVI to XXth centuries, was studied. Mineralogical characterization of the biscuit was made from X-ray diffraction patterns. Microstructural features (pore size) were determined using scanning electron microscope (SEM) photographs. Mechanical strength was determined with four-point bending tests. The absorption coefficient and the total amount of water retained were obtained from water absorption essays, which also allowed the estimation of the open porosity. The impregnation treatment, in general, increases the mechanical resistance, reduces the porosity and modifies the water absorption behaviour of the tiles.

A Study of the Effect of Wavelength on Q-Switched Nd:YAG Laser Cleaning of Eighteenth-Century Portuguese Tiles

Traditionally, the glazed surfaces of antique tiles have been cleaned by a mechanical process, or by using chemical solvents applied directly to the surface. These chemical and abrasive processes may result in accelerated degradation of the tile, particularly the fragile ceramic body, or in scratches on the glazed surface. Much useful conservation work has been accomplished using laser radiation, and this study describes an attempt to evaluate the usefulness of laser cleaning as a technique for ceramic tiles. A Nd: YAG laser, out-putting 1064 (infrared), 532 (visible, green) and 266nm (ultraviolet) radiation was used to clean dirty, glazed surfaces of eighteenth-century Portuguese tiles. To evaluate the results of the cleaning process, several analytical techniques, including optical microscopy, optical fibre spectroscopy and scanning electron microscopy, were used. Although the interaction with the surface was different at each wavelength, all the wavelengths tested were able to remove superficial dirt without damaging the underlying glazed surface, or the blue pigment; different ranges of fluence were required for the successful use of the different wavelengths. Laser radiation with a wavelength of 532nm was found to be the most effective for cleaning. Radiation at 1064nm produced yellowing of the surface and incomplete dirt removal, while ultraviolet radiation (266nm) showed a very superficial action, resulting in a very slow material removal rate.

A Study of the Effect of Wavelength on Q-Switched Nd:YAG Laser Cleaning of Eighteenth-Century Portuguese Tiles

A Study of the Effect of Wavelength on Q-Switched Nd:YAG Laser Cleaning of Eighteenth-Century Portuguese Tiles

The treatment of ancient Portuguese tiles

The treatment of ancient Portuguese tiles