Characterization of Egyptian bronze archaeological artifacts (original) (raw)
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The Characterization of a Corroded Egyptian Bronze Statue and a Study of the Degradation Phenomena
International Journal of Conservation Science, 2011
This paper presents the results of scientific examinations carried out on an Egyptian bronze statue discovered buried in Sais. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) were used to understand the corrosive morphological characteristics of the patina, to investigate the corrosion products, analyze the elementary composition of the statue and to identify the corrosive factors with effects on the alteration processes. The results indicated that the statue was made of bronze alloy, with copper as the main element, besides lead and tin. Three layers of alteration products with various composition and morphology covered the substrate of the bronze alloy. XRD results indicated that the statue was subjected to many corrosive ions such as sulfur and chloride, and buried in wet soil, rich in oxygen and carbon. This study provides useful information for the restoration and protection of the statue.
Chinese archaeological artefacts: Microstructure and corrosion behaviour of high-leaded bronzes
Metallographic features of ancient bronze artefacts often hide peculiar micro-chemical processes and corrosion behaviours, which are worth to be studied as they can provide conservators and archaeologists with valuable tools and information. It is widely documented that Chinese bronzes were cast and the way to adjust their properties was to change the alloy composition. In particular, addition of lead, which is insoluble in the bronze matrix, results in the formation of inclusions or globules, which undergo oxidation processes leading to their conversion into corrosion products. The mechanisms through which this occurs were still poorly investigated. The present work was conducted to further study the corrosion behaviour of high-leaded bronze, especially focusing on the behaviour of lead globules. To this aim, a collection of Chinese archaeological bronzes, showing intermediate steps of degradation, were selected and investigated. The use of combined microscopy-based, molecular and elemental, analytical techniques allowed the characterization as well as the precise location of corrosion products, thus enabling us to propose a degradation pathway basing on thermodynamic data provided by Pourbaix diagram. The achieved results will be useful for researchers involved in these kinds of studies to better interpret data obtained. (R. Mazzeo). Therefore, it is the authors' opinion, that an effective way to prove and validate hypothesis is to analyse archaeological samples exhibiting intermediate steps of degradation. The identification of intermediate stages of degradation has allowed us to propose a sequence leading to the overall substitution of the original lead globule into cuprite.
Characterization and Scientific Conservation of a Group of Archaeological Bronze Egyptian Statues
2016
Several archaeological bronze statuettes adhered randomly to a bigger statue of goddess Sekhmet as a big mass, which was excavated from Sais and most likely dates to C.600 BC, and was investigated and conserved. They were in a poor condition, retained intact their thick corrosion crust incorporated with residual burial soil. Both the surface corrosion products and the metal substrates were studied to understand the objects corrosion process and to obtain information about their chemical composition before the conservation procedures. Optical Microscopy (OM), X-ray diffraction analysis (XRD), and Scanning electron microscope equipped with energy-dispersive spectrometry (SEM-EDX) were used for disclosing corrosion features, the nature and composition of the patina, and compositional analysis of the study group. The results indicated that the objects have been buried in wet sandy saline soil or were exposed in storage to an environment rich in many aggressive ions such as chloride, sul...
Several archaeological bronze statuettes adhered randomly to a bigger statue of goddess Sekhmet as a big mass, which was excavated from Sais and most likely dates to C.600 BC, and was investigated and conserved. They were in a poor condition, retained intact their thick corrosion crust incorporated with residual burial soil. Both the surface corrosion products and the metal substrates were studied to understand the objects corrosion process and to obtain information about their chemical composition before the conservation procedures. Optical Microscopy (OM), X-ray diffraction analysis (XRD), and Scanning electron microscope equipped with energy-dispersive spectrometry (SEM-EDX) were used for disclosing corrosion features, the nature and composition of the patina, and compositional analysis of the study group. The results indicated that the objects have been buried in wet sandy saline soil or were exposed in storage to an environment rich in many aggressive ions such as chloride, sul...
More than 1800 bronze objects dating to c.600 bc were excavated from the site of the Sacred Animal Necropolis at Saqqara, Egypt between 1969 and 1971. While the important pieces had been accessioned by the Department of Ancient Egypt and Sudan and had been routinely cleaned using alkaline and/or acidic reagents in the 1970s, the residual group considered here, which includes numerous figurines and parts of sculpture, situlae and jewellery, had remained unregistered and uncleaned and so retained a burial corrosion crust. Both the metal substrates and the surface corrosion were studied to obtain information about objects that were under consideration for accession and to contribute to the wider study of this important site.
The recent acquisition of a sealed chamber with controlled humidity by the Museum of Archaeology and Ethnology of the University of São Paulo (MAE-USP) requires new methods for conservation and restoration of metallic objects in its collection. To establish new procedures for the identification of corrosion mechanisms and agents in the exhibition environment, and to set up new standards for conservation of the museum's collection, Proton Induced X-Ray Emission (PIXE) elementary analysis of some metallic objects is in progress, using the external beam facility at LAMFI. The first analysis involved metallic objects from the collection of MAE, two African statuettes "male Edans" from the Ogboni Secret Society, of the Ilobu-Iorubá ethnic group, one pectoral adornment from the Chimu culture, Peru and one anthropomorphic pendant from the Tairona culture, Colombia. The in air non destructive PIXE analysis allowed identifying major and some secondary components in the alloys and in the corrosion products on the samples, data that were used to identify the corrosion sources and to set up the exhibition environment.
Bronzes from the Sacred Animal Necropolis at Saqqara, Egypt: a study of the metals and corrosion
The British Museum Technical Research Bulletin 3, 2009
More than 1800 bronze objects dating to c.600 bc were excavated from the site of the Sacred Animal Necropolis at Saqqara, Egypt between 1969 and 1971. While the important pieces had been accessioned by the Department of Ancient Egypt and Sudan and had been routinely cleaned using alkaline and/or acidic reagents in the 1970s, the residual group considered here, which includes numerous figurines and parts of sculpture, situlae and jewellery, had remained unregistered and uncleaned and so retained a burial corrosion crust. Both the metal substrates and the surface corrosion were studied to obtain information about objects that were under consideration for accession and to contribute to the wider study of this important site.
Treatment and Conservation of Ancient Egyptian Bronze Objects from North Saqqara Excavations
2018
The French Archaeological Mission carried out excavations in the Bubasteion region, north of Saqqara. The results of these excavations were the discovery of a group of archaeological tombs dating back to the modern Kingdom in ancient Egypt. The French Archaeological Mission discovered a collection of bronze objects, including statues of various shapes, vessels and others. These bronze objects suffer from the presence of thick layers of corrosion products and several of deterioration phenomena. The documentation processes, recording and study of manufacturing techniques were discussed. Examinations of corrosion layers were investigated using Optical Microscope (OM) and Scanning Electron Microscope (SEM). Analysis of corrosion compounds were carried out using X-Ray diffraction (XRD) and (EDX). Treatment and conservation processes of these bronze objects were finished, which included the mechanical and chemical cleaning, the removal of the thick corrosion layers from the surface of the objects, Finally, the bronze objects were chemically isolated to protect their from corrosion and deterioration again.
Uncommon corrosion phenomena of archaeological bronze alloys
Applied Physics A: Materials …, 2006
In the framework of the EFESTUS project (funded by the European Commission, contract No. ICA3-CT-2002-10030) the corrosion products of a large number of archaeological bronze artefacts are investigated by means of the combined use of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and optical microscopy (OM) and tentative correlation of their nature with the chemical composition of the artefacts and the burial context is proposed. The results provide good insight into the corrosion layers and evidence in some bronze Roman coins and artefacts; the occurrence of uncommon corrosion phenomena that give rise to the formation of a yellowish-green complex chlorinephosphate of lead (pyromorphite, (PbCl)Pb 4 (PO 4) 3) and of a gold-like thick layer of an iron and copper sulphide (chalcopyrite, CuFeS 2). The micro-chemical and micro-structural results show that the coins were buried in a soil enriched in phosphorus for the accidental presence of a large amount of decomposing fragments of bones or in an anaerobic and humus rich soil where the chalcopyrite layer has been produced via the interaction between the iron of the soil, the copper of the coin and the sulphur produced by the decomposition of organic matter in an almost oxygen free environment. Finally, some unusual periodic corrosion phenomena occurring in high tin bronze mirrors found at Zama (Tunisia) are described.
X Study on the Specific Effects of Corrosion Processes on Ancient Bronze Artefacts
The paper presents the cases of the corrosion processes which take place on starting from the usage period when the primary patina is being formed and when the secondary patina starts, than continuing with the archaeological site where the contamination patina is obtained under the influence of the pedological processes. The paper is a review from the specialised literature and from the contributions of the authors. There has been used the direct analysis with optical instruments, electron microscopy and EDX.