The role of nuclear microprobes in the study of technology, provenance and corrosion of cultural heritage: The case of gold and silver items

Guerra, Maria; Tissot, Isabel

doi:10.1016/j.nimb.2012.11.053

Cited by 16 publications

(9 citation statements)

References 31 publications

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“…The information used for processing quantification comes from a layer whose thickness very much depends on the amount of gold (highest Z) in the alloy, the energy of the X-ray lines used for elemental quantification, and the type of incident radiation (charged particles or X-rays). Nevertheless, EDS always analyses a very thin layer, below 0.6 lm, which for untreated surfaces may suffer from the heterogeneities caused by tarnishing or corrosion during burial [18][19][20].…”

Section: Surface Analysismentioning

confidence: 99%

Gold from the tomb of Scribe Beri: a comparative analytical approach to the New Kingdom gold grave goods from Riqqa (Egypt)

Troalen

Guerra

2016

Appl. Phys. A

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The gold necklace and penannular earrings from tomb 296 at Riqqa, containing the coffins of a female and of a male, the latter a scribe named Beri of the reign of Tuthmosis III (eighteenth Dynasty Egypt), were analysed by PIXE, XRF, and EDS, together with eight penannular earrings from other find-spots of the same period. Analysis of jewellery items from tomb 296 at Riqqa revealed the use of high-purity gold alloys and electrum alloys, while the other earrings investigated were found to be made of electrum with high Ag content. Two earrings conserved in different museums were shown to be originally a pair. PIXE mapping revealed the extensive use of a hard soldering technique for the joints, with the solders being obtained by the addition of Cu to the base alloy. The presence of PGE inclusions indicated the use of alluvial gold, but the variability of their composition could be ascribed to the recycling of gold from different origins, in the case of some objects.

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Section: Surface Analysismentioning

confidence: 99%

Gold from the tomb of Scribe Beri: a comparative analytical approach to the New Kingdom gold grave goods from Riqqa (Egypt)

Troalen

Guerra

2016

Appl. Phys. A

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“…In most of the cases, silver colours present dramatic blackening, but in some manuscripts, the metal brightness is still present. Although the application of silver leaf in illuminated manuscripts has been referred by several authors [13][14][15][16][17][18][19][20][21][22][23][24][25], the study of silver degradation in the cultural heritage field has been mainly associated with metal artefacts, jewellery or composite objects such as altarpieces, polychrome and gilded objects, silver threads in textile, daguerreotype photos and silverpoint drawings [26][27][28][29][30][31][32][33][34][35][36][37][38]. Despite its importance for cultural heritage preservation, there is little consensus on the literature regarding silver degradation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Silver paints in medieval manuscripts: a first molecular survey into their degradation

et al. 2018

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The lack of comprehensive studies on silver paints in manuscripts is a handicap to new stabilization strategies and treatments. This work develops and tests a methodological approach for the study of the degradation of silver paints, at the molecular level, using as a case study a French Book of Hours dated from the 15th century from Mafra National Palace collection. In this paper, we show that the global equation commonly used by the cultural heritage community to describe the tarnishing of silver proves to be insufficient to understand the main factor causing its severe and extensive darkening in medieval illuminated manuscripts. This equation depicts the degradation of silver instantly with a sulphide containing species as H 2 S. Recent research has solidly proved that the first intermediate of silver oxidation is Ag 2 O. This theme will be presented in a forthcoming review. Within this framework, we selected four typologies of silver paints, all analysed by in situ techniques and four as microsamples; due to the very small size and fragility of the microsamples, new methods of sample preparation were developed and tested. The main research questions include: (1) understanding how silver-based colour are formed, disclosing its full stratigraphy; (2) define if the other compounds present, such as colour paints and the ground, may affect silver oxidation by stabilizing or accelerating it; (3) comprehend if it is possible to characterize the degradation products of silver paints with the methodology developed in this work, both in the bulk and at the interfaces between layers. Overall our results show that silver-based colours exhibit a complex stratigraphy that impacts its conservation condition. Further research at the molecular level is required on the correlation of the main components of the ground (binder and filler such as gypsum and calcium carbonate) and the paints that are applied as layers over or under the silver leaf. Our case studies have shown that both in situ analytical techniques and scanning electron microscopy with energy dispersive spectroscopy analysis in the microsamples, provide relevant information on the silver colour stratigraphy. However, the information obtained studying cross-sections is more accurate. We consider that the study of the degradation mechanism of silver in medieval illuminated manuscripts will require the combination of both approaches; in situ methodologies support the relevance of the data acquired on the microsamples. Microsamples studies will make possible the acquisition of data that is fundamental to understand the darkening of silver paints and this, in turn, is essential to develop informed and sustainable conservation policies.

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“…) caused by atmospheric corrosion. The fragment of torc Au283 (Fig. ) and the IA earring Au574 from Cabeço de Vaiamonte belonging to the NMA collection, showing a different visual aspect of corrosion, were analysed by SEM‐EDX and μ XRD for the identification of the corrosion products.…”

Section: Resultsmentioning

confidence: 99%

“…Their role has been published elsewhere (e.g.) . Appropriate protocols for the study of the alterations caused by atmospheric corrosion are still under development.…”

Section: Methodsmentioning

confidence: 99%

Bronze Age and Iron Age gold torcs and earrings from the Iberian Atlantic façade: a non‐invasive multi‐analytical approach to the characterisation of the alloys and the corrosion

Guerra

Tissot

2015

X-Ray Spectrometry

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A group of Bronze Age and Iron Age gold torcs and earrings from the Iberian Atlantic façade, several with tarnishing, are studied with different X‐ray‐based techniques, including portable devices for in situ analysis. The construction of the complex objects is discussed, and information on the evolution of the alloys is provided. By comparing the elemental composition of the analysed objects with published data for Bronze Age and Iron Age jewellery from the Portuguese area and with data obtained and published for Chalcolithic objects from the Iberian area, the changes in gold supplies could be discussed, and this has led to suggest changes in the chronological attribution of three torcs, on the reuse without melting of one pair of earrings and on the origin of the so‐called gold ingots. The analysis of tarnished areas of the torcs and the earrings showed the presence of distinct corrosion products due to atmospheric corrosion, which could be in part identified. Copyright © 2015 John Wiley & Sons, Ltd.

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The role of nuclear microprobes in the study of technology, provenance and corrosion of cultural heritage: The case of gold and silver items

Cited by 16 publications

References 31 publications

Gold from the tomb of Scribe Beri: a comparative analytical approach to the New Kingdom gold grave goods from Riqqa (Egypt)

Gold from the tomb of Scribe Beri: a comparative analytical approach to the New Kingdom gold grave goods from Riqqa (Egypt)

Silver paints in medieval manuscripts: a first molecular survey into their degradation

Bronze Age and Iron Age gold torcs and earrings from the Iberian Atlantic façade: a non‐invasive multi‐analytical approach to the characterisation of the alloys and the corrosion

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