Selected Publications by Ioanna Kakoulli
Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400–2500 nm),... more Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400–2500 nm), luminescence (400–1000 nm), and X-ray fluorescence (XRF, 2 to 25 keV) data, is uniquely equipped for noninvasive characterization of heterogeneous complex systems such as paintings. Here we present the first application of multimodal chemical imaging to analyze the production technology of an 1,800-year-old painting and one of the oldest surviving encaustic (" burned in ") paintings in the world. Co-registration of the data cubes from these three hyperspectral imaging modalities enabled the comparison of reflectance, luminescence, and XRF spectra at each pixel in the image for the entire painting. By comparing the molecular and elemental spectral signatures at each pixel, this fusion of the data allowed for a more thorough identification and mapping of the painting's constituent organic and inorganic materials, revealing key information on the selection of raw materials, production sequence and the fashion aesthetics and chemical arts practiced in Egypt in the second century AD. Advances in technology and miniaturization of chemical imaging technologies – adapted mainly from airborne scanners – including reflectance hyperspectral imaging (HSI) in the visible and shortwave infrared region (VSWIR, ~400 to 2500 nm) and scanning macroscale X-ray fluorescence (MA-XRF) spectroscopy 1–7 , have enabled their deployment in the field and in museums, making enormous strides for in situ noninvasive characterization and analysis of important works of art ranging from Old Masters' and modern paintings, to wall paintings and polychrome archaeological artifacts. Diffuse reflectance HSI in the VSWIR region provides information about molecular structure of inorganic and organic materials based on electronic and vibrational transitions (overtones and combination bands). Luminescence HSI (400–1000 nm) offers complementary information on the molecules and more specifically the intrinsic luminophores in the materials analyzed, based on their characteristic light emission (luminescence) after the absorption of photons initiated by photoexcitation at specific wavelengths. MA-XRF (2 to 25 keV) contributes with hyperspectral data (elemental distribution images), elemental information with photon emissions of characteristic X-rays. For the analysis of ancient paintings, multimodal imaging spectroscopy offers unparalleled potential in identification of both organic and inorganic materials, hitherto impossible without sampling and microanalysis. It further enables the mapping of both molecular and elemental data for every pixel in the image across the entire surface of the painting, thus aiding in accurate attri-butions and interpretations and informing on production technology and raw materials selection. Here we demonstrate the potential of multimodal chemical imaging spectroscopy with results from the fusion of the three data cubes obtained from diffuse reflectance and luminescence HSI and MA-XRF spectral imaging modalities, employed for the analysis of a complex and archaeologically significant Greco-Roman painting (" Portrait of a Woman ") of the second century AD, from the collection of the National Gallery of Art in Washington DC (Fig. 1). The data cubes from all three hyperspectral imaging modalities were co-registered, or spatially aligned to one another, which enabled the comparison of reflectance, fluorescence, and XRF spectra at each pixel in the image for the entire painting. This fusion of the data, or the comparison of the three different Published: xx xx xxxx OPEN
This paper focuses on the characterization of materials from fragmented pieces of an imperial lac... more This paper focuses on the characterization of materials from fragmented pieces of an imperial lacquer plate in the Luozhuang Han tomb, which dates to the early Western Han dynasty. Various non-invasive and minimally invasive techniques were performed, including optical and electron microscopy, XRF, Raman spectromicroscopy, FT–IR, XRD and THM-Py–GC/MS. The lacquerware pieces consist of a five-layer structure, which includes (from the top): a red pigmented layer, two lacquer finish layers, a ground layer and a canvas/wood foundation layer. The red layer consists of ground cinnabar mixed with urushi. The lacquer finish layers are made of urushi mixed with perilla or tallow tree oil, without any pigment. The ground layer is a mixture of organic materials including urushi, tree oil and amorphous carbon
Archeological campaigns along the track of the Domitian road in Cuma resulted in the recovery of ... more Archeological campaigns along the track of the Domitian road in Cuma resulted in the recovery of a large amount of pot-shards and crucible fragments (both open and closed forms), covered with residues of blue and green frits, respectively. Typological analysis of the crucibles combined with mineralogi-cal and petrological analyses on the ceramic body and frit residues revealed that the forms are intimately related to the technological data. Newly formed calcium silicates indicate high firing treatments of crucibles during pigment making (not lower than 950°C). In particular, different working temperatures for the two types of crucibles have been estimated by the presence/absence of sodalite-nosean feldspathoid. This mineral formed after the reaction of Si-Al-rich material (the sintered ceramic body) and alkalis transferred to ceramics via chemical diffusion during the pigment synthesis. Thus, the estimated working temperatures are higher for closed forms (>1100°C) and lower for the open ones (950–1050°C). This different thermal treatment perfectly fits with the temperatures of green and blue pigment synthesis; higher temperatures for green pigments allowed the formation of abundant Cu-bearing glassy phase, whereas, blue pigment is prone to the formation and thermal stability of cuprorivaite crystals (950–1050°C). Moreover, the two frits showed similar recipes (quartz-feldspar-calcite-rich sand) with the exception of more abundant Cu-bearing colorant agent in blue hue and higher proportion of alkaline flux in green frit. The obtained data suggested that crucibles were a fundamental tool for pigment manufacturing, likely one of the best example of ancient technical ceramics, as they permitted controlling the temperatures along with the fuel and the treatment time. Combining analytical and archeological data, the production and the technology of the two colored compounds identified as Egyptian Blue and Green frits in ancient Cuma has been inferred. Finally, considering the Vitruvius excerpt that identified an Egyptian Blue production in Puteoli, the area of production can be widen up to the northern Phlegraean Fields, also including Cumae and Liternum.
Fig. S1. Selected X-ray fluorescence spectrometry binary diagrams of crucibles; (a) major element... more Fig. S1. Selected X-ray fluorescence spectrometry binary diagrams of crucibles; (a) major elements; (b) trace elements. Blacks dots are type 1 crucibles, white dots are the type 2.
Table S1. Mineralogical and textural features of crucible pastes. Legend: sd (Φ), standard deviat... more Table S1. Mineralogical and textural features of crucible pastes. Legend: sd (Φ), standard deviation of Φ values; Abbreviations (after Whitney and Evans)[38]: Qz, quartz; Fsp, feldspars; Bt, Biotite; Ms, Muscovite; Cpx, clinopyroxene; Cal, calcite; San, sanidine; Pl, plagioclase; Ol, olivine; Amp, amphibole; Garn, garnet.
Table S2. Energy dispersive X-ray spectroscopy quantitative analyses of feldspars of crucibles pastes. Legend: pl, plagioclase; aFsp, alkali feldspar; T, temper; S, skeleton; N, newly formed minerals.
Table S3. Energy dispersive X-ray spectroscopy quantitative analyses of clinopyroxene of crucibles pastes. Legend: T, temper; N, newly formed minerals.
Table S4. Representative chemical composition of accessory minerals. Legend: Sod-Nos, Sodalite-Noseane; Ol, olivine; Amp, amphibole; Garn, garnet.
Table S5. Energy dispersive X-ray spectroscopy quantitative analyses of bulk, glassy phase, cuprorivaite, and clinopyroxene of the frit samples. The bulk chemical composition was measured by EDS area, results has been 100% normalized to eliminate the effect of different porosity, following the method proposed by Hatton et al.[3] *Crystals/Glass ratio was determined by Image Analyses of 300 × 300 μm BSE images.
Table S6. Energy dispersive X-ray spectroscopy quantitative analyses of accessory phases of the frit samples.
Two of the oldest synthetically produced and most widespread pigments employed in the decoration ... more Two of the oldest synthetically produced and most widespread pigments employed in the decoration of ancient polychrome artifacts are Egyptian blue, a vitreous blue compound, and madder lake, a hybrid organic-inorganic composite. Both of these pigments are known to be photoluminescent after electronic excitation by photons in the visible and re-emission of photons in the near infrared (NIR) and visible (Vis) respectively. The emissions of Egyptian blue are typically due to d-d electronic bands and for madder lake generally due to p-p* type transitions. In this research, the photophysical properties of these two pigments were examined by means of forensic photography. The usefulness of this type of imaging is based on the properties of Egyptian blue and madder lake in exhibiting characteristic near infrared and visible emissions when excited by red and green light respectively providing reliable fingerprint markers for their identification and mapping. To probe and capture the characteristic excitation and emission photon energies of Egyptian blue and madder lake an alternate light source (ALS) and a modified digital single-lens reflex (DSLR) camera with suitable optical filters were employed in the examination and analysis of two Canosa polychrome terracotta vases from the J. Paul Getty Museum collection dated to the third century BCE. Reference materials and supplementary analysis by fiber optic reflectance spectroscopy (FORS) and X-ray fluorescence (XRF) spectroscopy were used for verification.
The red mineral pigment known as cinnabar (HgS) was commonly employed in Roman fresco wall painti... more The red mineral pigment known as cinnabar (HgS) was commonly employed in Roman fresco wall paintings. Fresco artists of the period favored this pigment for its striking red color. However, upon excavation and exposure to air and light, cinnabar-pigmented surfaces recovered from archaeological contexts often proved to be unstable. Mural paintings colored with cinnabar that have been exposed in the open air frequently demonstrate a disfiguring, irreversible darkening of the surface. Traditionally, scholars have attributed this alteration to a light induced phase change from red a-cinnabar to black beta-cinnabar (meta-cinnabar). While this transformation has not been totally excluded, the prevailing view among conservation scientists is that chlorine plays a key role in the darkening process through the formation of light-sensitive mercury chloride compounds, or as a catalyst in the photochemical redox of Hg(II)S into Hg(0) and S(0). Using laboratory-based experiments and thermodynamic modeling, this paper attempts to further clarify the mechanism(s) and kinetics of cinnabar alteration in fresco applications, especially the role of light, humidity, and chlorine ions. Additionally, it explores possible pathways and preventive as well as remedial conservation treatments during or immediately following excavation, to inhibit or retard darkening of cinnabar-pigmented fresco surfaces.
Recent mineral-based approaches for stone and plaster consolidation have demonstrated considerabl... more Recent mineral-based approaches for stone and plaster consolidation have demonstrated considerable potential by bio-mimicking the growth of hydroxyapatite (HAP), the main mineralogical constituent of teeth and bone matrices. These initial conservation trials, together with significant fundamental research on the precipitation of HAP for bioengineering and biomedical applications, offer great potential in the use of HAP as a consolidating agent for archaeological bone and other similar matrices such as archaeological teeth, ivory, antler, and fossils. This study presents experimental results on the in situ synthesis of biomimetic HAP-based consolidation processes. Controlled application of diammonium phosphate precursors to bone flour, modern bone samples, and archaeological bones, indicated the formation of HAP with instantaneous increase in the cohesiveness of friable matrices and reduced water absorption while maintaining the physicochemical properties of the samples. These results point towards a promising new and more compatible method for the preservation of archaeological bone.
In the past decade Surface Enhanced Raman Scattering (SERS) has emerged as a powerful technique f... more In the past decade Surface Enhanced Raman Scattering (SERS) has emerged as a powerful technique for the analysis of artistic, historical and archaeological material culture. However, the identification of organic compounds in complex samples using SERS can be challenging owing to the complexity in optimizing the adsorption of target analytes onto the plasmonic substrate and the difficulty to identify proper areas on the sample for robust SERS analysis using optical systems. Scanning electron microscopy (SEM) interfaced with Raman spectromicroscopy (μRS) provides an ideal hyphenated system to overcome the last challenge by: (1) evaluating the nanoparticles coverage/distribution on the sample and (2) locating suitable areas for successful and reproducible SERS analysis. In this paper we demonstrate the potential of a system interfacing SEM and μRS for single fiber, extractionless analysis in the characterization of dyes from reference collections and archaeological textiles.
The art of wall painting in Cyprus during the transitional period from Greco-Roman to Byzantine t... more The art of wall painting in Cyprus during the transitional period from Greco-Roman to Byzantine times introduced a wide spectrum of painting materials that reflect the social structure and organization of the period, provincial and transregional interactions and technological savoir faire. These materials include natural minerals -locally available or imported -organic fibers, gums, oils, artificially produced, high-fired vitreous composites and other chemically synthesized products. This paper investigates and presents the in situ alteration mechanisms that certain wall paintings have undergone due to physical and chemical processes caused by the adverse microclimate in enclosed rock-cut structures. It also proposes sustainable preservation strategies based on a holistic methodology, integrating novel scientific techniques for non-invasive in situ examination with state-of-the art non-destructive analysis of microsamples at the molecular scale.
Book: book: From mine to microscope: Advances in the Study of Ancient Technology, 2009
Variable pressure scanning electron microscopy Backscattered electron imaging Byzantine wall pain... more Variable pressure scanning electron microscopy Backscattered electron imaging Byzantine wall paintings a b s t r a c t Evidence suggests that asbestos, a fibrous form of serpentine or amphibole was discovered and used in Cyprus since ancient times. In the first century AD, Pedanius Dioscorides in his treatise De Materia Medica V.138, refers to "líqo2 ἀmíanso2" [lithos amiantos], a fibrous stone from Cyprus, cleansed by fire that was mainly used to manufacture fabrics. Other ancient Greek and Latin authors make reference to the use of this natural resource mainly for the production of textiles and oil-lamp wicks. Additional known uses of asbestos in antiquity include ceramic production as evidenced by the discovery in Finland of 2000 BC asbestos-tempered ceramic ware. The exploitation and use of this fibrous rock in the manufacture of cements, however, was thought to be a novelty of the late nineteenth century. Here we show that 'amiantos' composites were in existence in Byzantine Cyprus, emerging much earlier than the start of the modern asbestos industry. The identification of chrysotile mineral in CaCO 3 -rich uppermost plaster coatings, just beneath the paint layer, in twelfth century Byzantine wall paintings in the Enkleistra e place of reclusion e of Saint Neophytos, provides direct evidence for the earliest use of asbestiform fibres in wall-painting finish coatings. We demonstrate that Byzantine monks were familiar with the fabrication of asbestos-fibre composites and their superior properties over more common CaCO 3 /organic fibre plasters, traditionally used in Byzantine wall painting. We support that chrysotile fibres were exploited for their good physical, flexural, and insulating properties.
Pre-Columbian populations that inhabited the Tarapacámid river valley in the Atacama Desert in C... more Pre-Columbian populations that inhabited the Tarapacámid river valley in the Atacama Desert in Chile during the Middle Horizon and Late Intermediate Period (AD 500−1450) show patterns of chronic poisoning due to exposure to geogenic arsenic. Exposure of these people to arsenic was assessed using synchrotron-based elemental X-ray fluorescence mapping, X-ray absorption spectroscopy, X-ray diffraction and Fourier transform infrared spectromicroscopy measurements on ancient human hair. These combined techniques of high sensitivity and specificity enabled the discrimination between endogenous and exogenous processes that has been an analytical challenge for archeological studies and criminal investigations in which hair is used as a proxy of premortem metabolism. The high concentration of arsenic mainly in the form of inorganic As(III) and As(V) detected in the hair suggests chronic arsenicism through ingestion of As-polluted water rather than external contamination by the deposition of heavy metals due to metallophilic soil microbes or diffusion of arsenic from the soil. A decrease in arsenic concentration from the proximal to the distal end of the hair shaft analyzed may indicate a change in the diet due to mobility, though chemical or microbiologically induced processes during burial cannot be entirely ruled out.
This project focuses on the characterization of materials from burial offerings and painted decor... more This project focuses on the characterization of materials from burial offerings and painted decoration in a royal Maya tomb at El Zotz, Guatemala, and their association with mortuary rituals. Archaeological findings included vessels, jade masks, organic materials (wood, cord, and textiles), specular hematite cubes, shells with powdered cinnabar, green (malachite) painted stucco assumed to have decorated the wooden bier where the king was resting, and caches of lip-to-lip Aguila Orange bowls containing human phalanges. In this paper we describe preliminary findings from non-invasive and non-destructive analytical techniques including XRF, VPSEM-EDS, and XRD, emphasizing the potential of these combined technologies in the identification of organic and inorganic markers to infer burial customs. The nature and location of the findings, the evidence of pigment coloration on the bones employing hematite and cinnabar, and the indication of exposure of the bones to high temperatures suggest highly complex, even protracted mortuary practices of Maya elite.
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Selected Publications by Ioanna Kakoulli
Table S2. Energy dispersive X-ray spectroscopy quantitative analyses of feldspars of crucibles pastes. Legend: pl, plagioclase; aFsp, alkali feldspar; T, temper; S, skeleton; N, newly formed minerals.
Table S3. Energy dispersive X-ray spectroscopy quantitative analyses of clinopyroxene of crucibles pastes. Legend: T, temper; N, newly formed minerals.
Table S4. Representative chemical composition of accessory minerals. Legend: Sod-Nos, Sodalite-Noseane; Ol, olivine; Amp, amphibole; Garn, garnet.
Table S5. Energy dispersive X-ray spectroscopy quantitative analyses of bulk, glassy phase, cuprorivaite, and clinopyroxene of the frit samples. The bulk chemical composition was measured by EDS area, results has been 100% normalized to eliminate the effect of different porosity, following the method proposed by Hatton et al.[3] *Crystals/Glass ratio was determined by Image Analyses of 300 × 300 μm BSE images.
Table S6. Energy dispersive X-ray spectroscopy quantitative analyses of accessory phases of the frit samples.
Table S2. Energy dispersive X-ray spectroscopy quantitative analyses of feldspars of crucibles pastes. Legend: pl, plagioclase; aFsp, alkali feldspar; T, temper; S, skeleton; N, newly formed minerals.
Table S3. Energy dispersive X-ray spectroscopy quantitative analyses of clinopyroxene of crucibles pastes. Legend: T, temper; N, newly formed minerals.
Table S4. Representative chemical composition of accessory minerals. Legend: Sod-Nos, Sodalite-Noseane; Ol, olivine; Amp, amphibole; Garn, garnet.
Table S5. Energy dispersive X-ray spectroscopy quantitative analyses of bulk, glassy phase, cuprorivaite, and clinopyroxene of the frit samples. The bulk chemical composition was measured by EDS area, results has been 100% normalized to eliminate the effect of different porosity, following the method proposed by Hatton et al.[3] *Crystals/Glass ratio was determined by Image Analyses of 300 × 300 μm BSE images.
Table S6. Energy dispersive X-ray spectroscopy quantitative analyses of accessory phases of the frit samples.