Browsing by Author "Melo, Helena P."
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- Annunciation or Adoration? The workshop practice and the hesitations of a Portuguese mannerist painter revealed by infrared reflectographyPublication . Melo, Helena P.; Cruz, António João; Valadas, Sara; Candeias, AntónioThe examination with infrared reflectography of the Annunciation and the Adoration of the Shepherds, two panels from a dismembered altarpiece attributed to the mannerist painter Francisco João (doc. 1558–1595), revealed the first documented example in Portuguese painting of the overlapping of two underdrawing layouts, each with a different subject, in a single panel painting. The paintings were examined under visible radiation and infrared reflectography was used to investigate the underdrawing in terms of the materials, graphic layout and function. Results from a previous study on the ground layers and underdrawing materials of these paintings, obtained with the analysis of micro-samples with microscopic and spectroscopic techniques, were used in the context of this research. Infrared images revealed that the underdrawing of the Annunciation mostly corresponded to the painted image but that two subjects — Annunciation and Adoration — were drawn over the prepared surface of the panel depicting the Adoration. This discovery is the first example of this procedure in Portuguese painting. The comparison with a third panel attributed to the painter, depicting another version of the Annunciation, allowed for the discussion of relevant technical procedures such as the use of cartoons, the responsibility for each main stage of painting creation and the reality of labour conditions in a regional market. The results contributed with material evidence to the scarce information of archival nature about the working methods of Portuguese mannerist painters.
- The Matter from Which an Orange Colour Is Made: On the Arsenic Pigment Used in a Portuguese Mannerist PaintingPublication . Cruz, António João; Melo, Helena P.; Valadas, Sara; Miguel, Catarina; Candeias, AntónioThe painting The Descent from the Cross, painted in 1620 by Pedro Nunes (1586–1637), presents two large figures with orange-coloured fabrics with conservation problems. Through the analysis of two samples with several analytical techniques, especially scanning electron microscopy combined with X-ray spectroscopy and Raman microscopy, it was possible to conclude that the orange colour is due to a complex artificial pigment made of amorphous arsenic sulphide. It essentially consists of spherical particles obtained by sublimation and condensation, possibly from orpiment, which ended up being joined with irregularly shaped particles resulting from crushing of the residual fraction obtained by solidification and fusion. This is a rare documented case of the extensive use of artificial arsenic sulphides in European easel painting, especially outside Italy. The conservation problems can be explained by the great sensitivity of the arsenic sulphides to photodegradation and the formation of powdery compounds.
- The use of glass particles and its consequences in late 16th century oil painting: A Portuguese case based on the analytical results and the technical treatisesPublication . Melo, Helena P.; Cruz, António João; Valadas, Sara; Cardoso, Ana Margarida; Candeias, AntónioColourless glass particles were identified for the first time in Portuguese paintings in two altarpieces attributed to the painter Francisco João, active between 1558 and 1595. They were found in red glazes with conservation problems. The glass was analysed by SEM-EDX and the binder by μ-FTIR. Portuguese 17th century painting treatises, which record earlier practices, were examined providing additional information. The glass particles had a vegetable silica-soda-lime composition, different in the two altarpieces, and a medium to very high alumina content. Although the provenance of the glass could not be determined, the use of local glass is suggested, as archaeological glass of the same period and similar composition has been found in southern Europe, notably Portugal. Furthermore, the glass from one of the altarpieces closely matches the composition of glass found in a painting by the Spaniard Luis de Morales. As a result, it is possible that the painter deliberately added a local glass to his red lakes, as advised in the two Portuguese painting treatises of this period. The exclusive presence of glass in the uppermost medium-rich glazes suggests that it was mainly used for its transparency and assumed siccative role. Although the siccative properties of glass have not been proved, by lowering the oil concentration in the paint, the addition of glass might have indirectly assisted the drying of the glazes. The glass particles were subject to a severe leaching of the alkali, a degradation that might explain the disruption of the glaze layers in these paintings.