Crete, the largest and most populous Greek island, occupies a central role in Byzantine art. However, eastern Crete (Lassithi) remains underrepresented in art historical and archaeometric literature, limiting a comprehensive understanding of regional Byzantine artistic practices and their development. To address this gap, this paper documents a systematic, multi-analytical study of Byzantine mural paintings from eleven churches in Lassithi (8th-16th century). It focuses on the identification and use of red pigments, and aims to characterize the composition and execution techniques of paintings through a combination of in-situ and laboratory analyses consisting of pXRF, FORS, PLM, SEM-EDS, and mu XRD. The results indicate a consistent but variable use of red ochres, vermilion, and red lead. Of these, ochres are the most frequent pigment, appearing in a range of typologies and purity levels. Vermilion, though costly, was more widely used than previously assumed, appearing not only in focal iconographic elements, but also in borders and underlayers. Red lead was also found in mixtures and degraded layers. Data relating to the lime-based matrices suggest the common use of a secco technique, with painters adapting their approach based on material and visual requirements. The results show local continuity in pigment choices and application, with gradual changes over time, contributing new insights into the technical features of Byzantine mural paintings of the region, along with a valuable reference dataset. In addition, several degradation phenomena identified in this study, including the thermally induced pigment transformation and humidity-related chromatic alterations, carry direct implications for conservation practice.

Azurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO3·Cu(OH)2), is one of the Middle Ages’ most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive multi-analytical approach, the study analysed several unexpectedly black-appearing details (objects such as books or clothing such as veils, robes, or mantles) in Antoine de Lonhy’s works. The aim was to investigate if the black colour was due to intentional iconographic reasons, incautious restoration work, or painting deterioration. The analytical results displayed the presence of the blue pigment azurite, therefore, the expected original colour of various areas should be blue. To shed light on the discussion regarding the blackening, several other Renaissance paintings with similar black details were analysed, all from the same period and geographic area as de Lonhy’s works and conserved under identical conditions. The reasons why the blackening takes place are still unclear. However, the combined use of X-ray fluorescence spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), portable X-ray diffraction (XRD), and the elemental mapping based on the XRF data revealed that these blackened areas were originally painted with azurite, suggesting they were once blue. This finding significantly changes the overall appreciation of these artworks.

Roman wall paintings at the archaeological site of Ostia Antica dating from the 1 st century BCE to the 4 th century CE were studied in an integrated noninvasive approach using portable instrumentation, namely: Nuclear Magnetic Resonance (NMR), Hyperspectral Imaging (HSI), X-ray fluorescence (XRF), Visible Induced Luminescence (VIL), External Reflectance Fourier-Transformed Infrared Spectroscopy (ER-FTIR), Raman and Near Infrared (NIR) Spectroscopies.The objective of this study is threefold: to investigate the materials and techniques of wall paintings at Ostia Antica in order to gain insight into the evolution of the use of materials and painting techniques over time, the testing of novel instrumentation in archaeological contexts such as portable HSI and the recently developed NMR hardware and stratigraphy protocols, as well as to aid in the conservation efforts at the site by providing information on the material composition of the walls.Some of the main results of four campaigns dating 2019-2023 are presented.

The white ground crater by the Phiale Painter (450-440 BC) exhibited in the "Pietro Griffo" Archaeological Museum in Agrigento (Italy) depicts two scenes from Perseus myth. The vase is of utmost importance to archaeologists because the figures are drawn on a white background with remarkable daintiness and attention to detail. Notwithstanding the white ground ceramics being well documented from an archaeological and historical point of view, doubts concerning the compositions of pigments and binders and the production technique are still unsolved. This kind of vase is a valuable rarity, the use of which is documented in elitist funeral rituals. The study aims to investigate the constituent materials and the execution technique of this magnificent crater. The investigation was carried out using non-destructive and non-invasive techniques in situ. Portable X-ray fluorescence and Fourier-transform total reflection infrared spectroscopy complemented the use of visible and ultraviolet light photography to get an overview and specific information on the vase. The XRF data were used to produce false colour maps showing the location of the various elements detected, using the program SmART_scan. The use of gypsum as the material for the white ground is an important result that deserves to be further investigated in similar vases.

The scope of this paper is to clarify some residual doubts left by a previous diagnostic study on Centuripe vases. In the previous work, imaging techniques, including visible and Ultraviolet photographs, combined with X-Ray fluorescence and Fourier Transform Infra-Red spectroscopies, elucidated the manufacturing technique, the materials used and their application methods. In addition, a helpful procedure to establish the originality of the vases was found.Despite the promising results obtained, some doubts remained about the nature of the copper-containing blue pigment and the composition of some areas, which are not accessible to the instruments given the vase morphology. To clarify these questions, two innovative imaging techniques, Visible Induced Luminescence (VIL), which allows for visualizing Egyptian blue only, and SmART_Scan, a procedure that plots elemental maps based on the XRF data, were applied. In this way, restoration interventions not found in the previous study were evidenced, and, at the same time, more robust evidence further demonstrating the originality of the Centuripe Vases of the Museo Archeologico Regionale "Antonino Salinas" di Palermo were obtained.

The main objective of this study is to establish an appropriate method for the characterization of the pigments, materials and structure of the paint layers in a copy of the painting the Transfiguration of Christ by Raffaello Sanzio. A multi-technique approach that combines elemental, molecular and structural analyses and involves optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM–EDX), μ-Attenuated Total Reflection–Fourier Transform InfraRed (µATR-FTIR), μ-Raman spectrometry (µRS) and non-invasive portable diffractometer (pXRD) was used. Our results revealed that this copy of the Transfiguration was executed with a palette, which includes white lead (cerussite and hydrocerussite), lazurite from lapis lazuli pigment, red and yellow earths (goethite, hematite and lepidocrocite), lead tin yellow, cinnabar, red lake, smalt and bone black, and fillers such as calcite, baryte (an impurity associated to some pigments), and traces of colorless powdered glass. A secondary objective of this research was the application of non-invasive in situ pXRD measurements, which do not require painting sampling and helped to confirm some inconclusive results obtained with other techniques regarding the artist's palette. The results showed the crystalline nature of all the pigments identified, which were known from ancient times and available during the 16th and 17th. Lastly, the used of 14 C accelerator mass spectrometry determined that the canvas date was 1451–1633 AD (with a 95% confidence level). Although the main focus of the work was to improve the analytical methodology to better understand the artist’s palette, our results will further help us to explore the authorship of the copy or the school that executed it. Graphical Abstract

Two mural paintings located in the “House of Garden”, recently excavated in the Regio V of the archaeological site of Pompeii (Campania, Southern Italy), were studied. The mural paintings are in room 3 of the house. The first is a large-scale scene representing Venus with a male figure (possibly Adonis or Paris since he has a bow) and Eros, while the second one is a fine female portrait, perhaps depicting the domina of the house. All analyses were carried out in situ , using a new non-destructive methodology based on the acquisition of good-resolution visible images and the chemical information obtained by a portable hand-held X-ray fluorescence device. All data were statistically combined using a computer program, named SmART_scan, obtaining maps of the distribution of the elements (or compounds) on the painting. Visible induced luminescence (VIL) was used to confirm the presence of Egyptian Blue. The study performed on the two mural paintings allowed us to identify the various pigments used and to determine the presence of degradation products, such as soluble salts and a violet-black discoloration that, in the first painting, has modified some of the original colours, producing substantial changes in the interpretation of the figures. The results of the work show that the SmART_scan methodology, coupled with an X-ray fluorescence device and a good-resolution visible image, is a valid tool for obtaining the spacial distribution of each element and often of the pigments as combination of them, on large surfaces in a short time and at low cost.

XRF scanners recently have become the most effective tools for analyzing the distribution of pigments on paintings. They are noninvasive and portable and can be used on flat surfaces of notable dimensions. Powerful miniaturized X-Ray tubes combined with more sensitive detectors make it possible to mount instruments on sturdy motorized X,Y devices, and reduce time needed for a scan. The high-resolution results obtained are of the utmost interest for conservators, art historians and conservation scientists. Drawbacks of XRF scanners are the elevated cost and the bulk of the X,Y devices, which makes them more difficult to transport. It is our opinion that the amount of information collected by a scanner is somewhat redundant. Uniform portions of the painting may be treated as a unity. Following this basic idea, a procedure is proposed to combine a high-resolution visible image with compositional measurement carried out on a grid with a much smaller number of points. Different types of images, spatially registered with respect to the visible one, can be used to increase the amount of information available. A computer program, named SmART_scan, statistically combines all available data, and generates false color maps that show the distribution of elements (XRF), or of compounds [XRD or Raman (Tracey et al., 2006)] over the surface. Even so, the collected information still seemed overabundant. For this reason, the program was adapted to work with a limited number of representative points selected by the user. The measuring time was enormously reduced, and the results were reasonably good. The program can be applied retroactively to previously collected data, provided that a good image, the accurate position of the measurements and their numerical results are available. Examples of maps relative to mockups, real paintings, cross sections and three-dimensional objects are shown.

The mural paintings in Santa Maria foris portas church at Castelseprio (Lombardy) are a precious early medieval cycle datable between 9th or 10th century CE and are therefore among the oldest Carolingian in Italy. The painting cycle has been analysed in situ, to characterise the palette used in its decoration, with non-invasive molecular and elemental techniques. In addition, Visible Induced Luminescence (VIL) has been applied to assess the extended use of Egyptian blue within the painting cycle. The palette, beside the use of the expected pigments, is characterised by the diffuse presence of Egyptian blue, more than 500 years after the fall of the Western Roman Empire. A remarkable feature in the composition of Egyptian blue is the presence of non-negligible amounts of zinc, indicating a non-traditional production of it. In fact, the use of a copper/zinc alloy rather than the more common copper/tin or copper/arsenic proper of bronze residues as source of copper, has never been previously reported.

Visible induced luminescence (VIL) is a powerful imaging technique applicable mostly to Egyptian Blue (EB hereafter). It is based on the ability of EB to absorb visible light and luminesce in the near‐infrared region. Han Blue Han Purple and some cadmium‐based pigments also luminesce, although with much lower intensity. The basic tools needed for the imaging are a digital camera with the IR filter removed, and a source of visible light without an IR component. The environmental IR noise needs to be reduced to a minimum. Many different variations of this basic setting have been proposed, from LEDs to flash with IR cutting filters. The presence of EB traces, even small, on works of art is a strong indication of their authenticity, since it is believed that the EB manufacturing technique was lost with the fall of the Roman Empire, although exceptions have been found. Using VIL, some information can be gathered on the EB history.

This lecture will begin by providing a definition of Cultural Heritage from the perspective of Conservation Science, taking account of the radical challenge that the advent of new materials in contemporary art has posed to the field of conservation.Over the past 45 years I have applied my experience as a crystallographer to answer questions and find solutions to many problems raised by the material dimension of cultural heritage.This lecture will showcase a series of crystallographic interventions in the field of conservation science, from Maya Blue structure, elucidated using synchrotron and neutron powder diffraction to Tutankhamen tomb paintings, from Michelangelo censure panels in the Sistine chapel to a hidden face under a Rembrandt painting.My talk will address some of the ways crystallography has and can contribute to conservation science in the areas of archaeometry and conservation, such as: o Enormous advances in instrumentation for the analysis and identification of specific compounds o Use of neutrons for CT-scan of large statues, compared to powerful X-ray sources and medical equipment.o Use of hand held XRF, Raman, FTIR.New noninvasive portable XRD/ XRF o Development of imaging techniques o Design and creation of non-invasive instruments for crystallographic analysis to answer questions relating to archaeometry and conservation.I hope to highlight the unique contribution that crystallography can make to the widening field of Conservation Science in the preservation of our ever more challenging cultural heritage.

The conservation of the architectural surfaces in the tablinum of the House of the Bicentenary at the ancient Roman site of Herculaneum is a collaborative project of the Getty Conservation Institute, the Herculaneum Conservation Project and the Soprintendenza Pompeii. The tablinum was selected as a case study given the significance, beauty, and severe deterioration of its decorated surfaces. A multi-disciplinary team with a wide range of expertise, comprised of conservators, chemists, geo-physicists, engineers, and conservation scientists, worked in partnership across a number of institutions with the objective to study the wall paintings in the tablinum. Scientists and conservators worked together to test the feasibility of portable techniques and in situ investigations to better understand Roman painting technology; identify previous restoration materials; determine the presence of alteration products; and characterize deterioration mechanisms commonly found on architectural surfaces at archaeological sites of the Vesuvian Region. The collection and interpretation of the instrumental data has been critical to the design and implementation of appropriate passive and remedial interventions to stabilize the architectural surfaces and mitigate deterioration. The paper will present the results of the investigations using portable instrumentation along with a discussion of the capabilities and limitations of each technique and the practical implications of their use for architectural surfaces on archaeological sites.

Noninvasive techniques have become widespread in the cultural heritage analytical domain. The popular handheld X-ray fluorescence (XRF) devices give the elemental composition of all the layers that X-rays can penetrate, but no information on how atoms are bound together or at which depth they are located. A noninvasive portable X-ray powder diffraction/X-ray fluorescence (XRD/XRF) device may offer a solution to these limitations, since it can provide information on the composition of crystalline materials. This paper introduces applications of XRD beyond simple phase recognition. The two fundamental principles for XRD are: (1) the crystallites should be randomly oriented, to ensure proper intensity to all the diffraction peaks, and (2) the material should be positioned exactly in the focal plane of the instrument, respecting its geometry, as any displacement of the sample would results in 2 θ shifts of the diffraction peaks. In conventional XRD, the sample is ground and set on the properly positioned sample holder. Using a noninvasive portable instrument, these two requirements are seldom fulfilled. The position, size and orientation of a given crystallite within a layered structure depend on the object itself. Equation correlating the displacement (distance from the focal plane) versus peak shift (angular difference in 2 θ from the standard value) is derived and used to determine the depth at which a given substance is located. The quantitative composition of two binary Cu/Zn alloys, simultaneously present, was determined measuring the cell volume and using Vegard's law. The analysis of the whole object gives information on the texture and possible preferred orientations of the crystallites, which influences the peak intensity. This allows for the distinction between clad and electroplated daguerreotypes in the case of silver and between ancient and modern gilding for gold. Analyses of cross sections can be carried out successfully. Finally, beeswax, used in Roman-Egyptian paintings as “encaustic” and in form of emulsion (modified wax), can be detected and, based on the shape of the peaks, these two ways of applying the wax can be distinguished from one another.

El monolito mexica descubierto por el Programa de Arqueologia Urbana hace una decada no solo destaca por sus imponentes proporciones y su inusitada vista frontal de la advocacion femenina de la deidad de la Tierra, sino tambien por la conservacion de la policromia original. Su intenso colorido brinda al espectador moderno sensaciones ineditas e imposibles de experimentar con otras culturas que han perdido su capa pictorica como la Piedra del Sol, la Coatlicue o la Coyolxauhqui.

Diagnostics based on X-ray computed tomography (CT) are becoming increasingly important, not only in the medical field but in industry and cultural heritage. CT devices typical for medical applications, however, can seldom be used on art objects because both they are not easily transportable and they often present high X-ray absorption. It is therefore necessary to make use of portable instrumentation and/or to develop tomographic systems optimized to the characteristics of the objects under examination. This work describes the computed tomography of a first century A.D. Roman bronze statue of Cupid (96.AB.53) in the collection of the J. Paul Getty Museum, within the collaborative framework between the Getty Conservation Institute and the Department of Physics and Astronomy (DIFA) of the University of Bologna (Italy). The tomography performed at the Getty facilities employed a 450 kV X-ray tube and a detection system developed at DIFA. The study highlighted the casting and construction techniques used by Roman foundry workers and provided information on the status of conservation of the statue. A 3D virtual reconstruction allowed the user to define different cross-sections enabling the study of the internal features.

Unvarnished twentieth-century oil paintings are often sensitive to aqueous swabbing, a method routinely employed by conservators for surface cleaning. This study proposes a connection between sensitivity and the presence of magnesium sulphate heptahydrate which has been identified on the surface of some of water-sensitive paintings. The probable source of magnesium is magnesium carbonate, an additive in some twentieth-century oil paints, which has reacted with atmospheric sulphur dioxide (SO2). Films made using modern manufactured paints and formulations made in the laboratory were exposed to gaseous SO2 and raised relative humidity and examined using scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction to characterize the crystalline entities. Films containing magnesium carbonate formed magnesium sulphite and sulphate hydrates. Films containing zinc oxide were also investigated. These formed zinc and sulphur containing salts. Sensitivity to swabbing with water before and after exposure was evaluated. Films that developed salts, demonstrated increased sensitivity to aqueous swabbing after exposure to SO2. Findings suggest that increased water sensitivity may be due to a combination of the formation of hygroscopic degradation products and to weakening of the paint film due to salt-induced disruption of the surface.

This paper describes the technical study of a suite of French Rococo chairs at the J. Paul Getty Museum with original eighteenth-century gilding preserved under layers of restoration. A variety of analytical methods was employed to identify and characterize the materials of the preparatory layers and gold alloys including optical microscopy, digital image analysis, polarized light microscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), Raman spectroscopy, and X-ray diffraction (XRD). The materials and techniques were compared with descriptions of French eighteenth-century gilding practices in contemporary artists' treatises. Both burnished and unburnished original gilding, employing distinctive techniques, were found. The study was particularly focused on the gold alloys and the support layer for burnished gilding, a mixture known as assiette in French and as bole in English. In addition to the original gilded surface, several subsequent campaigns of gilding executed with the same eighteenth-century techniques were present on the chairs and visually indistinguishable from the original gilding. The alloy of the gold leaf used in each campaign was characterized through quantitative SEM-EDX via a calibration generated from the SEM-EDX data from gold standards. Characterization of the gold alloys proved to be a vital tool for the interpretation of the layer structure and identification of original gilding.

A large number of instruments, as well as new analytical procedures, have been developed recently and applied to archaeometry and conservation science. Here, an effort is made to summarize the most important such developments, with particular reference to the Earth and mineral sciences. Non-invasive or micro-invasive techniques are emphasized, i.e. those developed with the goal of reducing, as much as possible, the impact of sampling on art objects. The examples described are taken mostly from the work of the author and his colleagues and address problems in both archaeometry and conservation. Examples of objects in collections, of building materials and of archaeological materials are all considered.

Previous articleNext article No AccessColor in American PrehistoryColor in monumental Mexica sculptureLeonardo López Luján and Giacomo ChiariLeonardo López Luján Search for more articles by this author and Giacomo Chiari Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Res Volume 61-62Spring-Autumn 2012 Published in association with the Peabody Museum of Archaeology and Ethnology, Harvard University Article DOIhttps://doi.org/10.1086/RESvn1ms23647839 Views: 211Total views on this site © 2012 by the President and Fellows of Harvard College. All rights reserved.PDF download Crossref reports no articles citing this article.