De Colorando Auro: Experiments and literature study of medieval colouring recipes on gilded plates

In the restoration-conservation practice of medieval art masterpieces, such as the Holy Lady Shrine from Huy, knowledge about the techniques used to create and shape them is of major importance, especially when they concern the surface finishing treatments. This influences the selection of methods employed for the conservation-restoration process. This paper discusses the method and the materials that might have been employed to modify the colour of gilding on silver. Recipes for chemically modifying the colour of the gilded surface can be found in medieval texts and might have been used on the masterpiece discussed in this paper. This article gives an overview of technical instructions related to this topic and presents a method to interpret their contents in order to be able to implement them. It reports observations carried out during the implementation tests, such as information about the temperature, timing, and other important elements. It concludes with the visual and the colorimetric results on the samples after application of the tested recipes.     

A bronze statue of a Meroitic archer-king: New data

Abstract

The bronze archer-king statue, masterpiece of the Sudan National Museum in Khartoum, was discovered in 1974 on the site of Tabo, Argo Island, in North Sudan. Its aesthetical and technological qualities inspired archaeologists to perform a complete study and full conservation in Zurich in the 1970s. The multidisciplinary work included iconographic and scientific investigations as well as defining a conservation protocol, and the results were published in 1986. On the occasion of an exhibition in Paris entitled Méroé: Un empire sur le Nil in 2010, a complementary study was conducted in the Centre de recherche et de restauration des musées de France (C2RMF) while restoration treatment was carried out. With a 40-year gap between the first work and the present effort, this example demonstrates, on one hand, the evolution of technological analysis methods and progress in the study of metallurgy and materials. On the other, it shows how the restart of necessary conservation interventions could be based on detailed knowledge of the first protocol and treatment.     

Gessoes in Portuguese Baroque gilding grounds,part 1: A study of historical documentary sources

The surviving gilded and polychrome altarpieces and sculptures in Portuguese churches, and the historical documents relating to them, offer an opportunity for understanding material and technological choices regarding gesso grounds. This paper focuses on the historical documentary research about gessoes — one aspect of a wider research project which also involved investigation of physical/chemical evidence, and archaeological reconstructions of gilded gesso grounds. Documentary research sheds light on the meaning of the terms used in historical documents, and on artists’ choice of materials and practices, production, and trade patterns of materials. It informs technological investigations and conservation decisions. The paper also stresses the importance of the evidence gained by using the historical and archaeological methodology applied in material culture studies, in which documentary, analytical, and experimental information complement and/or elucidate each other, leading to a comprehensive understanding of this technology.     

Study of the deterioration products,gilding, and polychromy of the stones of the Scuola Grande Di San Marco's façade in Venice

The Scuola Grande di San Marco is one of the most outstanding Renaissance buildings in Venice. Destroyed by fire in 1485, the Scuola was reconstructed between 1487 and 1495 by Pietro Lombardi (and sons), together with Giovanni Buora and Mauro Codussi. The façade is considered one of the finest and most original exteriors of Venetian buildings and in particular features refined sculptural and painted decorations and a remarkable pictorial effect created by the extensive use of polychrome marbles and the false perspective view between the pilasters of the lower order. Most of the stone materials (Istrian and Verona red limestones, nero di Roveré, pavonazzetto toscano, Carrara marble and various reused antique marbles) present evident decay phenomena such as scaling, exfoliation, powdering, fissuring, salt efflorescence, black crusts, and artificial patinas of various kinds. The present study reports the results of petrographic and chemical laboratory analyses carried out in preparation for the conservation treatment of the building, in order to characterize the main micro- and macro-morphologies of decay and to identify the causes and mechanisms of deterioration as well as the nature and application technique of the polychromy, gilding, and patinas present on parts of the monumental Renaissance façade.     

Characterization of the organic materials used in the painting of the vaulted ceiling at the Saadian Tomb of Mulay Ahmed Al-Mansour (Marrakech)

The Saadian tombs from the era of sultan Ahmed al-Mansour (1574–1603) are beautifully decorated and have always been a major attraction for visitors to Marrakesh. The central mausoleum, named the Hall of Twelve Columns, encloses the tombs of Ahmed al-Mansour and his family. The hall has a huge vaulted ceiling, carved cedar doors, opening windows with wooden marquetry screen (Mashrabiya), and grey Italian marble columns. This paper presents the first attempt to identify the organic materials used by the Moroccan artisans. A GC/MS analytical procedure was used for the characterization of lipids, waxes, resins, pitch, tar, proteinaceous and saccharide materials in the same paint micro-sample. The analytical study identified the organic materials used in the polychrome and gilded decorations of the walls, ceiling and dome of the hall. Data showed that the polychrome decorations were painted using animal glue as a binder, and highlighted the treatment of the wall surface with linseed oil and the retouching of the paintings based on a saccharide binder. The use of a proteinaceous-resinous-oil mixture, applied on a proteinaceous preparation layer, for the gilded decorations revealed a very similar technique to that used at the time in Europe for mural paintings.