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- Synchrotron X-ray diffraction of bole layers from Portuguese gilded baroque retablesPublication . Barata, C.; Rocha, F.; Cruz, António João; Andrejkovicová, S.; Reguer, S.Studies based on a scientific approach to materials and techniques used in Portuguese gilded retables from the Baroque are very scarce and focus particularly on works with erudite features and on the characterization of the superficial gold leaf. The conservation and appearance of gilded surfaces, however, depended on the qualities of the clayey ground layer underneath, which is the bole. Colour and texture are closely related to its mineralogical composition. Boles were healing clays. Red to orange varieties could also be used for gilding, usually agglutinated with animal glue when the gold surface was meant to be burnished. Armenian was the name used to identify the best quality material. Microsamples collected from erudite and popular gilded retables, respectively belonging to the city of Oporto and its rural surroundings, were selected for elemental and mineralogical characterization. It was intended to shed light on the characteristics of boles used in Portuguese retables and to understand if there are any differences between materials used in works of distinct artistic quality. Elemental analysis was performed through SEM–EDS. SR-XRD was used for phase identification, performed with a six-circle diffractometer at the DIFFABS beamline of SOLEIL Synchrotron. Portuguese clay standards of identifiable composition and provenance were also analysed. The results suggest that boles are mainly kaolinitic, with variable amounts of illite and smectite. Gypsum was used as an extender. Although the proportions of the main clay minerals are similar in erudite and popular works, in Oporto homogeneity is clearly higher.
- Paint, Colour, and Style: The Contribution of Minerals to the Palette of the Descent from the Cross, Attributed to the Portuguese Painter Francisco João (act. 1558 1595)Publication . Melo, Helena; Cruz, António João; Sanyova, Jana; Valadas, Sara; Cardoso, AnaThe paint materials and techniques of The Descent from Cross, a panel painting attributed to the Portuguese painter Francisco João (act. 1558–1595), were investigated with a combination of visible, ultraviolet, and infrared imaging and an analysis of paint samples with microscopic, spectroscopic, and chromatographic techniques. The colour palette is composed of lead white, lead–tin yellow, minium, vermilion, ochres of different colours, umber, smalt, azurite, verdigris, charcoal black, and a variety of different-coloured red lakes made of brazilwood and cochineal. An oil-based medium was identified. The characterisation of the pigment mixtures, paint build-up, and particular paint handling techniques enabled us to determine their role in the style and formal appearance of this painting and to discuss Portuguese painting practices in the larger context of 16th-century European painting. Mineral and elemental associations or impurities in the blue pigments, as well as degradation issues affecting minium, and smalt paints were reported. In particular, the deterioration of the glass matrix in some of the smalt particles mixed in lead white paint raises special concern.
- "O livro de como se fazem as cores" or a medieval Portuguese text on the colours for illumination: a reviewPublication . Afonso, Luís U.; Cruz, António João; Matos, Débora
- Desenvolvimento de uma metodologia para a interpretação de espectros de microfluorescência de raios x dispersiva de energia (EDXRF): análise de um conjunto de pigmentos de referência e estudo da sua composição elementarPublication . Saraiva, Sandra; Cruz, António João; Calvo, AnaUm dos principais métodos de análise usados na identificação de pigmentos é a espectrometria de fluorescência de raios X dispersiva de energia (EDXRF). A sua relevância suscitou o interesse pelo desenvolvimento de uma metodologia de interpretação de espectros de EDXRF que permita minimizar os principais problemas resultantes da sua aplicação no estudo de obras de arte no âmbito da Conservação. Como primeira abordagem nesse sentido apresenta‑se um conjunto de espectros de 74 pigmentos, que assim fica já disponível para referência, de que fazem parte muitos que mostram significativas diferenças entre o que se esperava e o que efectivamente surge nesses espectros. Além de se discutirem os principais casos nessa situação, é ainda chamada a atenção para outros que, numa situação de análise real de uma obra, provavelmente originariam interpretações incorretas.
- Conservation Publications - IIC member's reviews of international periodicals: PortugalPublication . Cruz, António João
- Italian Influence in a Portuguese Mannerist Painting (Part II): A Matter of Image or a Matter of Technique?Publication . Melo, Helena Pinheiro de; Cruz, António João; Valadas, Sara; Cardoso, Ana Margarida; Helvaci, Yigit Zafer; Candeias, AntónioThe panel depicting The Descent from the Cross, painted in 1620 by the Portuguese artist Pedro Nunes (1586-1637), shows a clear Italian formal influence. The painter’s colour palette was identified in another paper. The panel is now investigated from a technical perspective, discussing aspects related to the support, preparatory system, and paint layer build-up. The research is based on the visual inspection of the painting’s surface with complementary imaging techniques and on the analysis of the materials from the preparatory layers with microscopic and spectroscopic techniques. The characterisation of the painting technique revealed an ingenious use of colour that is based on the understanding of the optical and handling properties of oil paint. This knowledge is illustrated by the painter’s ability to exploit and combine a range of different oil painting techniques, such as glazing, scumbling, wet-in-wet, or wet-in-dry painting; by his formulation of a wide variety of pigment mixtures; and by his use of diverse and often complex layering systems - some quite unconventional for Portuguese painting practice. The material and technical originality of this painting clearly reflects Nunes’ international Roman experience and his desire to update the Portuguese mainstream practice of his time.
- Estudo técnico da tela Efeitos de luz num armazém de Abel Salazar: um trabalho representativo da sua produção pictórica finalPublication . Brito, Ana; Calvo, Ana; Cruz, António JoãoO presente artigo aborda o estudo de alguns processos criativos de Abel Salazar (1889 – 1946), baseado em fontes documentais, e reforçado por reconstruções técnicas pictóricas do autor. Aborda o estudo técnico e material da pintura de grande formato sobre tela Efeitos de luz num armazém, nomeadamente as características do suporte, preparação, desenho e pintura. Para este estudo recorreu‑se a diferentes métodos de exame e análise, nomeada‑mente fotografia de luz do espetro visível, UV e IV à pintura; observação por microscopia ótica (MO) e análise com microscopia eletrónica de varrimento com espectrometria de raios‑X por dispersão de energia a (SEM‑EDS) micro‑espectroscopia de infravermelho com transformada de Fourier (μ‑FTIR) de amostras recolhidas da obra. São apresentados os resultados analíticos que permitiram complementar a identificação de procedimentos técnicos e determinar os materiais constituintes da pintura.
- Conservation intervention on an embroidery with beads on perforated cardboard: problems and solutionsPublication . Barros, Luciana; Cruz, António João; Loureiro, Leonor CPPerforated cardboard is a rigid material widely used during the second half of the 19th century as an embroidery support, but very little-known today. Intervention cases are rare, and so an intervention on a poor condition 1879 glass beads embroidered specimen is presented here. The intervention was a complex task, mainly due to the fragility of the object and the existence of different materials linked to each other, that did not allow the execution of treatments to which they are usually subjected when isolated. The most intricate operation was the simultaneous action of micro-consolidation and micro-infill. These involved the insertion of Japanese paper fibres and 4 % Tylose MH300 between the perforated paper layers, and the insertion of Japanese paper strips between the embroidery lines. For the embroidery housing, it was necessary simultaneously to avoid the most unfavourable conditions for both the preservation of the glass and the paper.
- MemóriasPublication . Cruz, António João; Freire, Luciano
- Oficinas regionais, influências de muitas e desvairadas partes: o caso dos suportes de madeira das pinturas maneiristas de Belchior de Matos da ermida de Geraldes (Peniche, Portugal)Publication . Cruz, António João; Ferreira, Elisabete; Lauw, Alexandra; Rego, Carla; Pereira, HelenaAs duas pinturas, representando Santa Luzia e o Martírio de São Sebastião, feitas por Belchior de Matos (c. 1570-1628) para uma pequena ermida de Peniche, no início do século XVII, têm suportes de madeira que as primeiras observações, realizadas no âmbito de uma intervenção de conservação e restauro, sugeriram ter excelente qualidade e influências de construção que contrastam com o que seria expectável numa encomenda menor de um modesto e mal pago artista de província. Por isso, com o objetivo de aprofundar o caso e contribuir para o conhecimento das pequenas oficinas regionais de pintura do período maneirista, foi feito um estudo pormenorizado desses suportes, incluindo a moldura e a camada de preparação, com recurso a métodos laboratoriais (observação com lupa binocular, fotografia, dendrocronologia, microscopia óptica e FTIR). Concluiu-se, efetivamente, que os painéis mostram que as oficinas regionais de pintura, ao contrário do que se poderia prever, não funcionavam necessariamente isoladas e fechadas sobre si próprias e podiam ter um diversificado conhecimento técnico que, além de soluções originais, envolvia práticas com diferentes origens geográficas, do norte ao sul da Europa, que, com mais estudos de casos, importa esclarecer até que ponto estavam ou não consolidadas em Portugal.