THE MYTH OF EL DORADO. MAKING AND APPLYING GOLD IN THE IBERIAN PENINSULA (15 TH -16 TH CENTURIES (original) (raw)
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Cambridge Archaeological Journal, 2015
Taking as a point of departure the in-depth analysis and description of an exceptional discovery, consisting of a large hammered gold sheet decorated with embossed motifs from the well-known Chalcolithic settlement of Valencina de la Concepcion (Seville, Spain), this article presents a general appraisal of the social and ideological role of gold in Copper Age Iberia. The information available for this find, including both its context and its inherent characteristics, opens up new perspectives for research into the technology, use, sociology and symbolism of gold during this time period. We describe and analyse this unique item in detail, including the characterization of the raw material used and the manufacturing process (via SEM-BSE and LA-ICP-MS), as well as an extensive reconstruction of the graphic motifs that are represented, by using digital imaging processing techniques (RTI). We compare this find with the data currently available for the (approximately) 100 Chalcolithic golden artefacts (or fragments of artefacts) found in Iberia to date. Finally, we present an appraisal of the social and ideological framework in which gold was used in Copper Age Iberia, discussing its relevance in aspects such as the dynamics of social complexity, worldviews or artistic creations.
2016
Pure gold is a soft, malleable, and ductile metal. These characteristics allow it to be hammered into thin leaves and applied to other surfaces, a process known as gilding. This study examines the gilding techniques used in Spanish panel and retable painting from the fifteenth to early sixteenth century, considering gold’s intrinsic value and symbolism as well as its role as a painting material. First, historical references and laboratory analyses of panel paintings will be compared and interpreted; second, important technical aspects of gold leaf will be discussed, including its composition and possible origin, its thickness and size, its price, and the different poliments and modes of adhesión used to apply it to the substrate.
Gold and not so real gold in Medieval treatises
Conservar Património, 2015
The aim of this study is to evidence diverse materials and processes used by artisans (and alchemists) required to synthesize a visually viable replacement for gold. The emphasis of the research is upon the production of mosaic gold or porporina, a pigment that has survived into modern times, which was used as ink and as paint. Base metals, mostly tin, but also alloys were used both into foils coated with glazes and varnishes and as pigment. The research focuses upon recipes documented in treatises dating from Antiquity to the late Medieval period (ca. 1500) and an attempt is made to answer two questions. In the first place, why was there a need for a surrogate? Secondly, why are there so few tangible examples detected on surviving artifacts? In conclusion, an argument is offered pointing out that, although much can be learned by scientific examination of artifacts, textual analysis is equally important and necessary to unravel mysteries of ancient technologies.
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.
Aesthetic and technical considerations regarding the colour and texture of ancient goldwork.
Metal Plating and Patination: Cultural, Technical and Historical Developments., 1993
The present surface of an ancient gold object, typically matt and often purer than the underlying metal, will not always reflect the originally intended appearance. The two variables are colour and texture. Colour could be controlled by choice of alloy (extreme varieties such as red copper/gold alloys are less common after the Bronze Age) or by surface treatments including etching to enrich the surface. Texture ranged from a bright shiny surface - naturally resulting from the soldering and other processes used or deliberately produced by abrasive polishing or burnishing - to a matt surface caused by chemical etching or, in theory, coarser abrasion. The processes used were often limited by the nature of the object, for example a granulated Etruscan ornament could not be burnished. This chapter considers the evidence, which although limited so far, tends to suggest that ancient gold jewellery was more often intended to be bright and shiny than its present appearance might suggest.
Applied Physics A, 2013
The colour of gildings can be modified by many artistic techniques. This article refers to the possibility of a specific chemical treatment to change the colour of gildings. The model samples-gilded silver plate, the mixture and the application of a medieval recipe based on ancient writings from Theophilius and Cellini have been described. We propose a strategy to identify the chemical processes involved in the change of colour of the metallic surface through the advanced study of these model samples. Synchrotron X-ray photoelectron spectroscopy and X-ray absorption spectroscopy were carried out both on the gilding with and without the application of the treatment with the aim to understand the chemical reactions occurring during the treatment.
Colorando Auro: third century colouring surface treatment of fire gildings
Surface Engineering, 2013
A few decades ago, heritage scientists and art historians started to study the ancient surface colouring techniques of metal art pieces. Colouring of copper and silver has already been broadly studied but no works on gold have been reported yet. This knowledge can be very important for art and technology history, conservation-restoration and surface sciences. This paper contributes to the investigation of the oldest recipe known so far to colour fire gildings. The chosen model samples, the mixture and the application of the recipe have been summarised by referring to the ancient writings known as the Arab and Syrian Alchemist Collection of M. Berthelot. The main aim of this research is to study the colour change obtained by applying the above mentioned recipe, and to identify the processes involved during this colour change. Digital imaging and scanning electron microscopy in combination with colorimetric measurements and elemental analysis have been performed to characterise the colour change and to identify its origins.
Analytical Study of Overlooked Bronze Age and Iron Age Goldwork from Northwest Portugal
METALLA
To gain further insight into the use of native gold and intentional gold alloys during the Bronze Age in Northwest Portugal, jewellery in the collections of three Portuguese museums was studied using an in-house built portable X-ray fluorescence spectrometer. Among the analysed objects are the Late Bronze Age bracelet from Monte Airoso (Viseu) and the Iron Age tubular bracelet from Regoufe (Aveiro). To shed more light on the manufacture of gold bracelets, have also been analysed all the components (bracelets, wires and bands) of the hoard of Arnozela (Braga), so far incompletely studied. The results obtained show that from the Middle Bronze Age onwards gold containing 8-11 wt.% silver is used, to which gradually increasing amounts of copper seem to have been added over time. These results support a heterogeneous chronology for the components of the hoard of Arnozela and show that the bracelet from Monte Airoso is made from an intentional gold alloy used in the Portuguese area ...
2016
During the second half of the 17th century and the first half of the 18th century, Portugal experienced a rising altarpiece production and an increased taste for gold application in church decoration. Some examples of this tendency can be found in the northwest of Portugal, particularly in the baroque altarpiece productions of Porto, Braga, Vila Real and Viana do Castelo. Porto was the first area studied and three gilded wood-carved altarpieces from different churches were selected: São Bento da Vitória (SB), Santa Clara (SC) and São Francisco (SF). Qualitative and semi-quantitative analyses of the samples were performed by optical microscopy (OM) of the cross-section using reflected and polarised light, and by scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS). The main advantages and disadvantages of the use of SEM-EDS were discussed and the results regarding the presence of major and trace elements compared. Résumé : Pendant la deuxième mo...