Katherine Eremin

Lithol Red: A Systematic Structural Study on Salts of a Sulfonated Azo Pigment

The first systematic series of single-crystal diffraction structures of azo lake pigments is presented (Lithol Red with cations=Mg(II), Ca(II), Sr(II), Ba(II), Na(I) and Cd(II)) and includes the only known structures of non-Ca examples of these pigments. It is shown that these commercially and culturally important species show structural behaviour that can be predicted from a database of structures of related sulfonated azo dyes, a database that was specifically constructed for this purpose. Examples of the successful structural predictions from the prior understanding of the model compounds are that 1) the Mg salt is a solvent-separated ion pair, whereas the heavier alkaline-earth elements Ca, Sr and Ba form contact ion pairs, namely, low-dimensional coordination complexes; 2) all of the Lithol Red anions exist as the hydrazone tautomer and have planar geometries; and 3) the commonly observed packing mode of alternating inorganic layers and organic bilayers is as expected for an ortho-sulfonated azo species with a planar anion geometry. However, the literature database of dye structures has no predictive use for organic solvate structures, such as that of the observed Na Lithol Red DMF solvate. Interestingly, the Cd salt is isostructural with the Mg salt and not with the Ca salt. It is also observed that linked eight-membered [MOSO](2) rings are the basic coordination motif for all of the known structures of Ca, Sr and Ba salts of sulfonated azo pigments in which competing carboxylate groups are absent.

Copper and antimony isotopic analysis via multi-collector ICP-mass spectrometry for provenancing ancient glass

Variations in the isotopic composition of Cu and Sb as determined using multi-collector ICP-mass spectrometry (MC-ICPMS) have been investigated as a proxy for provenancing ancient glass. Cu and Sb were added during the manufacturing of ancient (pre-Roman and Roman) glass to obtain colour and opacity. In previous work, the analytical methodology for sample digestion and isolation of Sb preceding isotopic analysis via multi-collector ICP-MS was developed. Although applications of Cu isotopic analysis can be found in the literature, this approach has not been used for provenancing glass raw materials yet. Therefore, the protocols for digestion and Cu isolation were optimized and validated, relying on the use of both an in-house multi-elemental standard and NIST SRM 610 glass reference material. The methods for Sb and Cu isotopic analysis were subsequently applied to a series of late Bronze Age Mesopotamian–Egyptian to Hellenistic–Roman glasses. Results obtained show that the isotopic composition of Cu, expressed as δ65Cu, varies from −1.9 to −0.2‰, thus covering a range of approximately 2‰. Unfortunately, the use of Cu isotope ratios to characterize raw materials used in glass manufacturing is complicated by the fact that Cu ores from within a single deposit can exhibit a similar range in δ65Cu values, certainly for co-existing Cu sulfides and oxides. Sb in stibnite ore, on the other hand, only shows a variance in isotopic composition of ∼10 e units (or 0.1‰), but Sb isotopic analysis offers more potential to pinpoint the location of an antimony source used in antiquity.

The facial reconstruction of an Ancient Egyptian Queen

The National Museums of Scotland Mummy Project has provided important new information about a burial excavated in Egypt. This has resulted in the facial reconstruction of a woman who was probably a queen at Thebes ca. 1570-1520 BCE. There are strong suggestions from the grave goods and her diet that this woman may have been ethnically Nubian rather than Egyptian. However, it is not yet possible to establish her ethnic identity for sure, so a definitive reconstruction of her appearance in life remains elusive.

X-ray fluorescence applied to overglaze enamel decoration on eighteenth- and nineteenth-century porcelain from central Europe

Abstract Technical and chronological aspects of overglaze enamel production at historic porcelain factories in central Europe are discussed based on studies of over 180 objects at various laboratories. Results of analyses on representative objects, carried out primarily with X-ray fluorescence spectroscopy, are presented. Examples of eighteenth- and nineteenth-century decoration by Meissen, Du Paquier, and Hausmaler painters are described in detail. The findings highlight established glaze formulation practices and enhance understanding of the dating of objects based on the detection of zinc in yellow, blue, and green glazes. This study is the first to provide extensive scientific evidence on the composition of nineteenth-century overglaze enamel colors. In particular, the research highlights the frequent co-occurrence of both eighteenth- and nineteenth-century enamel formulations on objects, underscoring the need to examine all overglaze enamel colorants on porcelains before attributing the decoration to a particular time period.

Monitoring of deposited particle levels within the museum of Scotland: During and after construction

Abstract Dust deposition and distribution were studied over an 18‐month period during the construction and installation of the Museum of Scotland (MOS) next to the Royal Museum of Scotland (RMS). Deposition levels were assessed by measuring the loss of reflectance of the surface of a clean glass microscope slide. Selected slides were examined by scanning electron microscopy to characterise the phases present. Levels were monitored in the established museum to assess dust ingress during construction. In the new museum, monitoring aimed to assess the effectiveness of containment measures during construction work, installation of displays and cleaning. During installation, dust levels at all sites in the MOS were up to fifteen times greater than those suggested for museums and galleries, with the highest values during the final stages of construction and installation. The major source of dust was ingress of external dust from the building areas to the installation areas, although some local generation of dust within the installation areas also occurred. Due to the high deposition levels measured, the sealing of the installation areas and the policing of dust containment procedures were improved. After opening, particle levels remained high compared to suggested values due to ongoing activities to finish the museum. During the final stages of installation and the post‐opening activities, dust levels were also elevated in the RMS, due to particle flow through the access corridors joining the two buildings. One year after opening, levels in both museums are below those suggested for museums and galleries. Results were obtained retrospectively and correlation to specific events proved more difficult than expected. This could be minimised by measurement of slides on‐site, using custom‐built equipment.

The making of Mark Rothko's Harvard Murals

Mark Rothkos Harvard Murals are a series of paintings on canvas commissioned by Harvard University and created in the early 1960s. The present study investigates Rothkos creative process, materials, and technique with ultraviolet and infrared imaging, analytical chemistry, cross-sectional analysis, and comparisons with the literature. Infrared and Raman spectroscopy imaging of cross sections help with the chemical mapping of the paint stratifications. A comparison of paper studies, studies on canvas, and the final five works installed give a detailed insight into Rothkos editing process. The intimate relationship between works on paper and canvas is traced by uncovering a back and forth between the two media, and the mixing of dry pigment with binder is a common theme for works on both supports. Motif developments, changes, and distinct painting campaigns become apparent with ultraviolet induced visible fluorescence imaging and infrared reflected infrared digital photography. Color measurements and microfading experiments give insight into the stability and light sensitivity of the materials used by Rothko in the Harvard Murals.

Understanding Glass Deterioration in Museum Collections through Raman Spectroscopy and SIMS analysis

The combination of Raman spectroscopy and Secondary Ion Mass Spectrometry can improve understanding of the chemistry of the glass alteration process. Formic and acetic acids play an important role in the alteration of museum glass objects placed in a humid atmosphere. Raman spectroscopy indicates that the soda-rich glass structure is modified differently when exposed to a humid versus a humid and polluted atmosphere at 60°C. Formic acid was not formed from soda-rich glass in the presence of carbon dioxide, high humidity and light.

On the chemistry of John and Robert Adamson's salted paper prints and calotype negatives

Abstract The chemical processes used by John and Robert Adamson and the possibility that they might have used some special ingredient has long been the subject of speculation. In the early stages of photography in Scotland, the chemical processes used were probably based on William Henry Fox Talbots, but it is likely that independent experimentation followed rapidly. Visual differences among the images produced by John Adamson and, to a lesser extent, David Octavius Hill and Robert Adamson, support the use of several different processes. In a few instances, annotations in the original albums or on the negatives provide tantalizing clues to the chemistry used, but these are scarce and there are no known notebooks left by either John or Robert Adamson to reveal their photographic recipes. They did, however, leave a vast corpus of images, which may be able to shed light on the chemical processes employed. This requires non-destructive analytical methods for determining the elements now present in the image and relating these to the chemicals employed originally.

Technical examination of enamels from the Botkin collection

Abstract This study examines a unpublished cloisonné enamel on gold, showing Christ Enthroned, in the collections of the Harvard Art Museums, and seven cloisonné enamels from the Walters Art Museum, Baltimore, the Museum of Fine Arts, Boston, the Detroit Institute of Arts, the Dumbarton Oaks Collection, Washington, D.C., and the Worcester Art Museum, all USA. All these pieces have a Byzantine appearance and were formerly in the possession of the Russian artist Mikhail Botkin (1839–1914). Botkins unusually large and homogeneous collections of Byzantine cloisonné enamels repeatedly raised doubts about the authenticity of many of the pieces, which were suspected to be modern imitations. Analytical and art-historical evidence, including X-ray fluorescence and scanning electron microscopy, confirmed that seven of the eight pieces examined were late nineteenth- or early twentieth-century copies of Byzantine originals. The study showed that there was a wide variety of enamel and metal compositions, with some differences in techniques used. These argue for creation in multiple workshops, over a period of time, and/or opportunistic use of materials. The exception is the enamel showing Christ Emmanuel (Walters Art Museum) which is more consistent with a genuine Byzantine piece and may be an original, although further study is required to confirm this.

Chapter 9:Glass

Vitreous materials, glazed stone and faience, were produced from about the 4th millennium BC and small glass objects from the late 3rd millennium BC but significant amounts of glass were not produced until around 1500 BC. The first glasses were probably made in Mesopotamia and/or Egypt.1 However, Eg...