Surface investigation of naturally corroded gilded copper-based objects

Ingo, G. M.; Riccucci, C.; Lavorgna, Marino; Luna, Martina Salzano de; Pascucci, Marianna; Carlo, Gabriella Di

doi:10.1016/j.apsusc.2016.06.082

Cited by 10 publications

(9 citation statements)

References 32 publications

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“…The sample surface was cleaned up by using first distilled water and then ethanol to remove adventitious carbon contamination and to assure dehydration (Ingo et al, 2016(Ingo et al, , 2018. The buckle was subsampled by taking a small representative fragment both of the layered corrosion products (patina) and the underlying metal substrate.…”

Section: Samplesmentioning

confidence: 99%

“…The sample studied in this work is part of a couple of firegilded metallic buckles found during the dredging of Tiber river (Rome, Italy) and dated back to 16th−17th century AD. They were the subject of previous works of the authors aiming to give elemental information about the structure of the artifacts, the corrosion products, and the degradation phenomena that occurred during the burial (Ingo et al, 2016(Ingo et al, , 2018. In the present work, we focused the attention on giving a more detailed information about the chemical species involved in such phenomena.…”

Section: Introductionmentioning

confidence: 99%

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Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

et al. 2020

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Three-dimensional chemical mapping was adopted to investigate an ancient fire-gilded buckle found in Rome. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used to detect and locate degradation products aiming to identify the alteration processes. Inorganic and organic compounds present in the outermost part of such a class of cultural heritage objects can be considered the result of long-term interaction with the burial environment. ToF-SIMS depth profiling experiments can provide chemical information at the molecular level and high resolved spatial information (about 1 µm laterally, and 1 nm in depth). In this work, the attention was focused on the identification and localization of the ionic and molecular species involved in the degradation process. Results showed the presence of copper oxides, chlorides, and sulfides as common corrosion products but also the presence of species related to copper and bronze corrosion process, such as atacamite and its polymorphs. 3D maps for all the relevant molecular species allowed to visualize at the same time the eruption of copper chlorides throughout the micro/nanochannels present on the gold surface, the recrystallization of compounds of minor elements from the substrate, a pathway followed by silico-aluminates from the surface toward the internal corrosion layers, but mostly the evidence of biological activity of Sulfur Reducing Bacteria (SRB) living in anaerobic conditions.

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Section: Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

et al. 2020

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“…In sample S35, Doge Grimani (Figure ), emerald‐green powdery reaction products have been observed (see Figure , between the letter M and A in the first quadrant of obverse side), which seem to be because of an aggressive corrosion reaction, better known as “bronze disease” for its deleterious and fast kinetics . Although not in the scope of the present study, this observation can be taken as a warning for the responsible of the collection to intervene with appropriate protection and remediation actions.…”

Section: The Samplesmentioning

confidence: 99%

Characterization of the mistura alloy used for Venetian sesino coins: 16th century

et al. 2018

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The information provided by material investigations on ancient coins is interesting in many respects, as concerns the archaeological and historical research.In this study a set of Venetian sesino coins, minted over a period ranging from 1554 until 1605, have been investigated in order to shed light on some aspects of the so-called mistura (mixture) alloy. The widespread diffusion of these relatively low-value coins of the Venetian Republic, commonly used in commercial transactions in the second half of 16th century, also outside the territories of the Republic, makes them an important proxy to be used in the reconstruction of the political and historical events of the period. The specific issue of the actual composition of the mistura alloy is herewith addressed for the first time, using a combined approach based on X-ray fluorescence and X-ray diffraction nondestructively applied to the analysis of the samples. It turns out that the mistura alloy, traditionally regarded as a Cu-Ag two phase alloy, over the latest period of circulation of the sesino coins, was actually made of copper only, still containing minor concentrations of lead, to be regarded as an impurity of the alloy and not as an intentional addition.

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“…Due to the variety of gilding methods used in the past and their intrinsic variations (amalgam composition and thickness), the investigation of archaeological gilded objects has raised interest in the community, aiming to investigate the methodology and materials used and the conservation state of these objects (Abdelhamid et al, 2010;Ingo et al, 2016Ingo et al, , 2018Graziani et al, 2020). The most straightforward way of studying a gilded objects' characteristics and gilding method is by analyzing a crosssection of the object.…”

Section: Introductionmentioning

confidence: 99%

“…This approach yields direct information of the thickness of the gold layer and the binding mechanism between gold layer and substrate. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) goes even further, giving a direct information on the chemical composition of the substrate and the gilding layer (Ingo et al, 2016). Nevertheless, the study of cross-sections requires sampling and is a destructive method, being rarely feasible when it comes to valuable artifacts (Nørgaard, 2017).…”

Section: Introductionmentioning

confidence: 99%

Differential X-Ray Attenuation in MA-XRF Analysis for a Non-invasive Determination of Gilding Thickness

et al. 2020

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When investigating gilded artifacts or works of art, the determination of the gilding thickness plays a significant role in establishing restoration protocols or conservation strategies. Unfortunately, this is done by cross-sectioning the object, a destructive approach not always feasible. A non-destructive alternative, based on the differential attenuation of fluorescence radiation from the sample, has been developed in the past years, but due to the intrinsic random nature of X-rays, the study of single or few spots of an objects surface may yield biased information. Furthermore, considering the effects of both porosity and sample inhomogeneities is a practice commonly overlooked, which may introduce systematic errors. In order to overcome these matters, here we propose the extrapolation of the differential-attenuation method from single-spot X-ray fluorescence (XRF) measurements to macro-XRF (MA-XRF) scanning. In this work, an innovative algorithm was developed for evaluating the large amount of data coming from MA-XRF datasets and evaluate the thickness of a given overlapping layer over an area. This approach was adopted to study a gilded copper-based buckle from the sixteenth to seventeenth century found in Rome. The gilded object under investigation was also studied by other analytical techniques including scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Previous results obtained from SEM-EDS were used to confront the data obtained with the proposed methodology and validate it. MA-XRF elemental distribution maps were fundamental in identifying and choosing sampling areas to calculate the thickness of the gilding layer, avoiding lead islands present in the sample that could negatively influence the results. Albeit the large relative standard deviation, the mean thickness values fell within those found in literature and those obtained from previous studies with SEM-EDS. Surface fissure has been found to deeply affect the results obtained, an aspect that is often disregarded.

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Surface investigation of naturally corroded gilded copper-based objects

Cited by 10 publications

References 32 publications

Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

Characterization of the mistura alloy used for Venetian sesino coins: 16th century

Differential X-Ray Attenuation in MA-XRF Analysis for a Non-invasive Determination of Gilding Thickness

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