Characterisation of Roman copper alloy artefacts and soil from Rakafot 54 (Beer Sheva, Israel)

The research presented in this paper focused on the preliminary non-destructive analysis of copper alloys, corrosion, and soil components from a Roman archaeological site in Israel. pXRF, XRD, and micromorphological analyses were carried out to gain a better understanding of the corrosion processes affecting the copper alloy artefacts, by characterising the alloy composition, soil environments, and corrosion products. Preliminary results indicate that the artefacts consist of copper-lead-tin alloys, covered by copper hydroxy-chlorides and lead sulphate phases with slight variations in their crystallisation. The multi-analytical approach revealed the presence of quartz, calcite, gypsum and feldspars in the sediments, while thin sections more specifically indicate loess soils with local micro-environments

TWO RECIPES FROM PORTUGUESE TRADITION OF GILDING ON WOODEN SUPPORT BETWEEN LABORATORY REPRODUCTION AND ANALYTICAL INVESTIGATION

This paper has the main purpose to compile and highlight the first data obtained from experimental studies on docμmented reconstructions of gilded composites performed within a research project on gilding materials and techniques in Portugal (www.gilt-teller.pt) funded by FCT. Two water gilding recipes were appropriately chosen from the treatises written by the Portuguese Filipe Nunes (1615) and José Lopes Baptista de Almada (1749) as being representative for Baroque époque. Based on these recipes, the production of raw materials - “gesso grosso”, “gesso fino”, bole, animal glue (from lamb and goat skins) - was made as faithful as possible. Their application was then performed in laboratory following the indications given by these authors or by treatises of previous époques (e.g. the Bolognese treatise for thawing leather), on plane and curved wooden supports (pine and oak species) using three types of leaf: gold (Au/Ag/Cu) of 22 and 23.75 karat respectively and silver. After the completion of gilding, the samples’ surfaces were divided into areas and on each different finishing layers (wax, animal glue size) and decorations (punching, “esgrafitado”, “estofado”) were applied. An analytical campaign using optical microscopy (OM) and scanning electron microscopy (SEM) on surfaces and cross sections, X-ray diffraction (XRD), microcomputerized tomography (microCT) and colorimetry (CIEL*a*b*) was undertaken in order to characterize the gilded composites and to assess the faithfulness of the reproductions in the laboratory. Correlations between the information given by the recipes and the composition and stratigraphical patterns of the reconstructions can be established. Furthermore, the study aims to highlight the difficulties encountered in analyzing real samples and comparing the results with those from reproductions as the number and types of layered materials are not always reproducible. A critical approach is needed and criteria for faithful reproduction of ancient recipes are suggested

Provenance study of the limestone used in the construction and restoration of the Batalha Monastery (Portugal)

To assess the provenance of the limestones used in the construction and restoration of the Batalha Monastery in central Portugal, stone samples collected from the monument and from five limestone quarries in the region surrounding the building were investigated by energy-dispersive X-ray fluorescence spectroscopy (ED-XRF), powder X-ray diffractometry (PXRD) and thermogravimetric analysis (TGA). Ca-Sr binary diagrams from the ED-XRF result indicated the source of the samples collected from different parts of the monastery. Thin-section observation supplemented the petrographic evidence for this identification. PXRD and TGA were also used to acquire information on the mineral and chemical composition of the stones. Preliminary results suggest that the monastery baluster was made of stone from the Valinho do Rei or Reguengo do Fetal quarries, whereas part of the church railing, the north-aisle eaves arch and Royal Cloister were made with stone from the Pidiogo or Cabeço do Roxo quarries

A combined petrographic and geochemical metrological approach to assess the provenance of the building limestone used in the Batalha Monastery (Portugal)

To verify the provenances of limestones that were used for construction and restoration of the Batalha Monastery, limestone quarries in central Portugal were investigated. Samples were collected from quarries and monastery in field investigation. The elements-alignment of calcium and strontium based on XRF result has suggested the source of fragments from different parts the monastery. Observation of the thin sections has supplemented petrographic evidence for this identification. XRD, TGA were also used for acquiring mineral information and chemical composition of the stones. This origin tracing result supplies foundation for further research of stone decay and reservation of the Batalha Monastery

A COMPARATIVE MULTI-TECHNIQUE INVESTIGATION ON MATERIAL IDENTIFICATION OF GILDING LAYERS AND THE CONSERVATION STATE OF 7 PORTUGUESE MANNERIST ALTARPIECES

This paper deals with the multi-analytical comparative characterization of 59 samples of gilded and polychrome layers from 7 altarpieces studied during the Gilt-Teller project (www.gilt-teller.pt). The altarpieces studied here belong to seven churches in the areas of Lisbon, Santarém, Portalegre and Guarda and display stylistic and constructive features characteristic to the Mannerism carved wood decoration in Portugal. The applied protocol of investigation characterized the structure and manufacture technique of gilding; identified the chemical composition of the layers constituting the gilded polychrome decoration; compared the materials and gilding techniques encountered in the 7 altarpieces and assessed the conservation state of each altarpiece. The analytical techniques applied to these purposes were: stereomicroscopy (SM), optical microscopy (OM), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX), X-ray diffraction (XRD), MALDI-TOF mass spectrometry, μRaman and μFTIR/imaging μFTIR spectroscopies. This interdisciplinary multi-scale approach was used to elucidate the aspects related to the material and technical aspects of “talha dourada” decoration, answering to these questions: which are the original materials and layers in the making of the polychromy and which are the ones added with posterior interventions; which are the relationships between gilding materials and techniques, regarding the degree of erudition of each case study; which were the main causes of degradation and influence to their conservation condition

meant to be discovered: the study bymicrossocpic analysis of lead-based pigments alteration by a fire

Meant to be discovered: the study bymicrossocpic analysis of lead-based pigments alteration by a fir

Characterizing Microbial Diversity and Damage in Mural Paintings

Mural paintings are some of the oldest and most important cultural expressions of mankind and play an important role for the understanding of societies and civilizations. These cultural assets have high economic and cultural value and therefore their degradation has social and economic impact. The present work presents a novel microanalytical approach to understand the damages caused by microbial communities in mural paintings. This comprises the characterization and identification of microbial diversity and evaluation of damage promoted by their biological activity. Culture-dependent methods and DNA-based approaches like denaturing gradient gel electrophoresis (DGGE) and pyrosequencing are important tools in the isolation and identification of the microbial communities allowing characterization of the biota involved in the biodeterioration phenomena. Raman microspectrometry, infrared spectrometry, and variable pressure scanning electron microscopy coupled with energy-dispersive X-ray spectrometry are also useful tools for evaluation of the presence of microbial contamination and detection of the alteration products resulting from metabolic activity of the microorganisms. This study shows that the degradation status of mural paintings can be correlated to the presence of metabolically active microorganisms

Characterisation of roman mortars from the historical town of Mertola

Ancient mortars from two Mertola’s important Roman monuments, the River Tower and the Cryptoportic, were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric and chemical analyses. The results show that all mortars are calcitic aerial lime mortars and that the aggregates are composed of quartzitic river sand and crushed schist. Samples from the River Tower and particularly sample taken from the outer layer of the Cryptoportic show the presence of crushed ceramics and neoformation pozzolanic reaction compounds

The importance of SEM-EDS analysis in the study of old mortars

The study of old mortars composition, using physical-chemical, mineralogical and microstructural characterization has an important role in the preservation of architectural heritage, allowing a deep knowledge about the materials used, construction techniques, possible repairs and degradation processes [1-4]. In this paper, we present representative results of the application of scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDS) analysis in the characterisation of ancient mortars from several historical buildings which illustrate the importance of the technique in complementing and corroborating information from other physical and chemical techniques normally used in the determination of their composition and state of conservation, namely, X-ray diffraction, thermogravimetric and differential thermal analysis, atomic absorption spectroscopy and optical microscopy

On the biodiversity and biodeteriogenic activity of microbial communities present in the hypogenic environment of the Escoural Cave, Alentejo, Portugal

Hypogenic caves represent unique environments for the development of specific microbial communities that need to be studied. Caves with rock art pose an additional challenge due to the fragility of the paintings and engravings and to microbial colonization which may induce chemical, mechanical and aesthetic alterations. Therefore, it is essential to understand the communities that thrive in these environments and to monitor the activity and effects on the host rock in order to better preserve and safeguard these ancestral artforms. This study aims at investigating the Palaeolithic representations found in the Escoural Cave (Alentejo, Portugal) and their decay features. These prehistoric artworks, dating back up to 50,000 B.P., are altered due to environmental conditions and microbial activity inside the cave. Microbial cultivation methods combined with culture-independent techniques, biomarkers’ viability assays and host rock analysis allowed us to better understand the microbial biodiversity and biodeteriogenic activity within the hypogenic environment of this important cave site. This study is part of a long-term monitoring program envisaged to understand the effect of this biocolonisation and to understand the population dynamics that thrive in this hypogean environment