Papers by Costanza Miliani
Heritage, 2021
The fugitive nature of the colorants obtained from sappanwood (Caesalpinia sappan L.) or the Sout... more The fugitive nature of the colorants obtained from sappanwood (Caesalpinia sappan L.) or the South American species commonly known as ‘brazilwoods’ (including other Caesalpinia species and Paubrasilia echinata (Lam.)) makes the identification of brazilwood dyes and pigments in historic artefacts analytically challenging. This difficulty has been somewhat alleviated recently by the recognition and structural elucidation of a relatively stable marker component found in certain brazilwood dyes and pigments—the benzochromenone metabolite urolithin C. This new understanding creates an ideal opportunity to explore the possibilities for urolithin C’s localization and identification in historical artefacts using a variety of analytical approaches. Specifically, in this work, micro-destructive surface-enhanced Raman spectroscopic methods following a one-sample two-step (direct application of the colloid and then subsequent exposure of the same sample to HF before reapplication of the colloid...
Heritage, 2020
We present the results of a diagnostic campaign on three of Giuseppe Capogrossi’s abstract painti... more We present the results of a diagnostic campaign on three of Giuseppe Capogrossi’s abstract paintings from the 1950s and 1960s, conserved at the National Gallery of Modern and Contemporary Art in Rome. Non-invasive investigations by reflection FT-IR spectroscopy were carried out, followed by micro-destructive laboratory analyses using Py-GC-MS, and HPLC-ESI-Q-ToF. The investigations focused on identifying the binders used for both the preparation and the pictorial layers. In two of the paintings investigated, an industrial preparation was identified based on egg yolk, mixed with other organic materials (acryl resin, oil, animal glue). The paint media include the use of both oil and alkyd paint. In one of the three paintings, the presence of a styrene-acryl resin was observed. The results show the simultaneous use of traditional and innovative materials, confirming the complexity of the period in which the artist was active, characterized by the technical experimentation of both the a...
Science Advances, 2020
A two-length scale spectroscopic approach unveils the composition and degradation state of CdS pa... more A two-length scale spectroscopic approach unveils the composition and degradation state of CdS paints in The Scream by Munch.
Heritage Science, 2020
Maya blue is a hybrid pigment where an organic component, indigo, is incorporated in a porous cla... more Maya blue is a hybrid pigment where an organic component, indigo, is incorporated in a porous clay. Despite its widespread use in the Mesoamerican artistic production and numerous studies devoted to understand the type of interactions between indigo and the host framework, its technology has not been completely unravelled yet. In this study portable non-invasive UV–vis reflection spectroscopy is proposed as a robust method for in situ investigation of Maya blue pigments. Laboratory mock-ups of powder Maya blue have been prepared employing different synthesis procedures (varying the nature of: clays, indigo–clay ratios, heating temperatures and time). The goodness of the prepared Maya blue samples—namely the occurrence of indigo–clay interactions—have been probed by micro-Raman spectroscopy and related UV–vis spectral markers have been identified. DFT calculations as well have been performed to deeply explain UV–vis profiles. The set of spectral markers have been finally exploited to...
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Chemistry (Weinheim an der Bergstrasse, Germany), Jan 6, 2018
Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used... more Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used by artists since the late 19th century. Despite being considered stable, they are suffering from discoloration in iconic paintings, such as Joy of Life by Matisse, Flowers in a blue vase by Van Gogh, and The Scream by Munch, most likely due to the formation of CdSO ⋅n H O. The driving factors of the CdYs degradation and how these affect the overall process are still unknown. Here, we study a series of oil mock-up paints made of CdYs of different stoichiometry (CdS/Cd Zn S) and crystalline structure (hexagonal/cubic) before and after aging at variable relative humidity under exposure to light and in darkness. Synchrotron radiation-based X-ray methods combined with UV-Vis and FTIR spectroscopy show that: 1) Cd Zn S is more susceptible to photooxidation than CdS; both compounds can act as photocatalysts for the oil oxidation. 2) The photooxidation of CdS/Cd Zn S to CdSO ⋅n H O is triggered...
Heritage Science, 2016
Alchemy (1947, Peggy Guggenheim Collection, Venice) is one of the most materic works by J. Polloc... more Alchemy (1947, Peggy Guggenheim Collection, Venice) is one of the most materic works by J. Pollock, whose palette is extensive, ranging from white to yellow, red, green, violet, blue, black, and silver. Each layer of color was laid on top of a previously dried one and effectively separated from the lower one forming a quite complex stratigraphy with colors intersecting each other. In this study, a non-invasive multi-technique method combining point analysis with Vis-NIR multispectral imaging has been exploited to give insights on the painting technique of the American abstract expressionist. The molecular identification of pigments, colorants and extenders contained in fifteen different paints has been achieved combining key spectral markers from elemental, electronic and vibrational spectroscopies. For those colors exhibiting similar hues but different chemical compositions, a mapping procedure based on false color rendering, obtained by properly mixing three spectral planes from the Vis-NIR multispectral imaging set, has been successfully applied. Relevant for the understanding of the evolution of Pollock's drip technique is the identification of both traditional oil-based paints and oil-modified alkyd media. Point analysis by reflection FTIR scattered throughout the painting enabled mapping the distinct use of traditional and new binding media among painted, squeezed and dripped paints.
Journal of the Chemical Society, Perkin Transactions 2, 2001
In this paper absorption and fluorescence spectra and emission quantum yields and lifetimes of th... more In this paper absorption and fluorescence spectra and emission quantum yields and lifetimes of the red colorants, carminic acid and its metal complex, carminic lake, were studied in solution and on painted surfaces. Accelerated photo-aging of carminic acid and lake was investigated in solution, in the presence and absence of a binder (arabic gum) commonly used in water-colour painting, while natural ageing was followed for several months on water-colour painted paper. The study of carminic acid in water as a function of pH showed that the absorption spectrum changes with pH. Four acid–base dissociation steps were detected and the corresponding pKs were determined from spectrophotometric and fluorimetric titrations. The fluorescence quantum yields (in the 10−2–10−4 range) and the lifetimes (on the sub-nanosecond timescale, 90–1000 ps) were markedly dependent on the pH of the medium. Excited state pK*s were calculated by means of the Forster cycle. The acidity decreased upon excitation for the first deprotonation step involving the –COOH group (ΔpK* = −1.9), but increased slightly for the successive deprotonation steps involving three phenolic hydroxy groups (ΔpK* = 0.6, 2.0 and 0.2, respectively). The results obtained from the aging experiments indicate that both carminic acid and lake are bleached during irradiation. While the binder prevents lake from fading, it destabilises the carminic acid. These findings are discussed in the light of the interactions of the dye with the solvent and matrix.
X-Ray Spectrometry, 2017
CRONO is a new portable and easy reconfigurable macro X-ray fluorescence scanner based on the ene... more CRONO is a new portable and easy reconfigurable macro X-ray fluorescence scanner based on the energy dispersive X-ray fluorescence technique, which has been specifically designed for in-situ, fast, and non-invasive elemental mapping of polychrome surfaces. The main components are fully integrated into the detection head which includes an X-ray tube, a large area silicon drift detector, a microscope camera, two pointing lasers, a Helium gas purging set, and fast acquisition electronics. This very compact detection head is mounted on motorized stages (with a linear speed up to 45 mm/s) that allow the scanning of areas up to 450 × 600 mm 2. Three collimators (0.5, 1, and 2-mm diameter) are software selectable to obtain different spot sizes on the sample. The typical measurement time for the full scanned area ranges from 1 h with the 2-mm collimator to about 9 h with the 0.5-mm collimator using a dwell time of 30 ms. Technical details and achievable performances of the instrument are presented and discussed along with an example of application which illustrates the value of the developed instrument in the investigation of paintings.
Angewandte Chemie, 2015
This paper presents firm evidence for the chemical alteration of chrome yellowp igments in VanGog... more This paper presents firm evidence for the chemical alteration of chrome yellowp igments in VanGoghs Sunflowers (Van Gogh Museum, Amsterdam). Noninvasive in situ spectroscopic analysis at several spots on the painting, combined with synchrotron-radiation-based X-ray investigations of two microsamples,r evealed the presence of different types of chrome yellow used by VanGogh, including the lightfast PbCrO 4 and the sulfur-rich PbCr 1Àx S x O 4 (x % 0.5) variety that is knownf or its high propensity to undergo photoinduced reduction. The products of this degradation process,i .e., Cr III compounds,w ere found at the interface between the paint and the varnish. Selected locations of the painting with the highest risk of color modification by chemical deterioration of chrome yellow are identified, thus calling for careful monitoring in the future.
Acta Crystallographica Section A Foundations of Crystallography, 2011
Microsymposia C198 dating from ca. 1550 BC onwards; of particular interest is the site at Armana ... more Microsymposia C198 dating from ca. 1550 BC onwards; of particular interest is the site at Armana which was occupied for a very short period of time (1350-1325 BC). Amarna is located in middle Egypt and was the seat of reigning God-King Akhenaten and Queen Nefertiti. Despite the prevalence of faience, the chemical makeup and manufacturing techniques used to produce it remain somewhat enigmatic. The work presented herein utilized X-ray absorption spectroscopy (XAS) and synchrotron powder diffraction (PD) techniques to examine a range of faience objects obtained from collections acquired in Amarna, in addition to a selection of faiences prepared in the laboratory. The artifacts for this study were provided by the Aegyptisches Museum, Berlin. Faience for comparison was synthesized using a base mix of 80 wt-% SiO 2 , 14 wt-% NaHCO 3 and 3 wt-% CaCO 3. Before firing at 900°C, Cu colorant was added to the equivalent of 3 wt-% Cu. Copper sources included bronze, corroded bronze, various natural minerals (malachite, azurite, turquoise, dioptase, chrysocolla, atacamite, etc), and laboratory chemicals (CuO, Cu 2 O, CuCO 3 , CuSO 4 , etc). XAS data were acquired at Beamline C, DORIS, HASYLAB. These data showed that all spectra acquired from the faiences were very similar, regardless of color, Cu concentration, or Cu source. However, analysis of the subtle differences between spectra reveal Cu coordination can be described as, either, i) a distorted Cu-O octahedron with some Si present in a fairly weak second coordination sphere, or ii) exhibiting a Cu-Cu second sphere of coordination. The former is consistent with data from glasses or related materials and the later suggests incomplete transformation to a glassy state. Such results may open avenues to use XAS to assess firing temperatures of ancient Egyptian faiences and to provide context on levels of control in ancient faience making. PD data were acquired using the powder diffraction beamline at the Australian Synchrotron which allowed the non-destructive examination of these precious artifacts. Data from the Egyptian faience show that the dominant crystalline phases present are quartz and tetragonal cristobalite. These results are suggestive of different maximum firing temperatures. Data acquired from samples synthesized in the laboratory, to different temperatures, affords additional information as to the mineral chemistry and thermodynamics of faience formation. This presentation will discuss the use of synchrotron techniques for the characterization of Egyptian faience and the subsequent outcomes.
Magnetic Resonance in Chemistry, 2014
With the aim of deepening the knowledge on the behavior of cyclododecane (CDD) as a temporary con... more With the aim of deepening the knowledge on the behavior of cyclododecane (CDD) as a temporary consolidant agent for weathered stones, NMR longitudinal and transverse relaxation decays have been exploited to follow the distribution of cyclododecane solutions into porous matrices. By measuring as function of time the relaxation decay constants of CDD solutions dropped onto porous supports, it has been possible to differentiate the step encompassing the solvent evaporation, which determines the consolidant migration within the matrix, from that governing the consolidant sublimation, which is related to the consolidation effectiveness over time.
Janssens/Modern, 2013
ABSTRACT
Journal of Raman Spectroscopy, 2014
Journal of Raman Spectroscopy, 2014
ABSTRACT In order to realize a surface enhanced Raman spectroscopy (SERS) gel protocol with porta... more ABSTRACT In order to realize a surface enhanced Raman spectroscopy (SERS) gel protocol with portable Raman instrumentation, this contribution oversees the optimization of a removable SERS active methylcellulose gel and the applicability of an innovative gelatin substrate. Analytical evaluations by non-invasive portable nuclear magnetic resonance (NMR) profilometry with regards to methylcellulose and gelatin film penetration and removal from an unvarnished painted surface and commercial dyed paper substrates have been carried out, respectively, following successful SERS measurements. Both gels have been specifically prepared in accordance to the substrate under exam so as to simultaneously permit sufficient surface interaction for Raman enhancements to be recorded with limited penetration into or subsequent damage on removal of the matrix under study. This work continues to bridge the gap towards non-invasive SERS measurements and in-situ SERS measurements. Copyright © 2014 John Wiley & Sons, Ltd.
SPIE Proceedings, 2011
In this paper a new compact and portable instrument for combined reflectance, time-resolved and s... more In this paper a new compact and portable instrument for combined reflectance, time-resolved and steady-state fluorescence is presented. All the optical parts of the apparatus, carefully described in the text, were chosen after an extensive market survey in order to obtain the best performances coupled with the smallest dimensions. This instrument through the use of a dedicated multiple fiber optic probe, allows the complete photophysical behaviors of investigated materials to be collected from the same point of the analyzed surface. In this way, the resultant instrumental setup is a portable device, usable in situ for non destructive and non invasive diagnostic purposes in the field of cultural heritage. Preliminary results concerning organic dyes characterization, which is the main application of luminescence-based diagnostic techniques in artworks, are presented and compared with those previously obtained using separate devices. Concerning reflectance data, improvements in the deep detectable UV spectral range have been achieved switching from the integrating sphere of the old instrument to bifurcated optical fibers used as probe in the new one. Special attention was devoted to test the instrument capability in order to obtain the true emission spectrum, corrected for the selfabsorption effect, for which good results were found. This particular experimental procedure is strongly recommended, by a diagnostic point of view, to avoid distortions in the instrumental responses, namely the spectral shape and emission maximum wavelength of a fluorophore as function of the color saturation.
Journal of the American Institute for Conservation, 2013
The Musée Picasso in Antibes (France) houses a unique collection of paintings and works on ... more The Musée Picasso in Antibes (France) houses a unique collection of paintings and works on paper by Pablo Picasso, completed during the fall of by the artist, working on the same premises occupied today by the Museum. Picasso painted with readily available materials including oleoresinous enamel paints, fibrocement, wood panels, paper sheets, and re-used canvases. In this paper the results of an extensive campaign of scientific analysis of of these works with both non-invasive and micro-invasive techniques are described. The project elucidated the full palette of the paintings, dispelling myths about their execution solely with the renowned brand of enamel paint Ripolin. The effective combination of elemental and spectroscopic methods of analysis enabled fine discriminations among various types of white enamel paint used by Picasso in Antibes. Because the artist appeared to have used such paints in chronological sequence, the precise identification of the type of white paint present on each of the works allowed the assignment of revised dates to some of the undated paintings. Important new information on surface coatings of wax and modern polymeric varnishes, as well as the widespread presence of metal soaps including zinc oxalates, was also uncovered.
Journal of Raman Spectroscopy, 2011
ABSTRACT The design and synthesis of a tailor-made surface-enhanced Raman scattering (SERS) activ... more ABSTRACT The design and synthesis of a tailor-made surface-enhanced Raman scattering (SERS) active film that is fabricated to be removable from the surface of an artwork under study following effective measurements is detailed. It is shown that silver nanoparticles prepared by green chemical reduction with glucose can be effectively doped into a methylcellulose (MC) matrix for the formation of a gel, which can be subsequently applied to a minute area (ca 1–1.5 mm) of an artwork without posing a threat to its integrity. Studies have been aimed at characterizing this film's chemical and physical properties, with regard to the stability of the nanoparticles dispersed within the MC, the ease of application of the viscous gel, its speed of drying and the transparency of the dry film for SERS measurements. Importantly, results have led to reproducible SERS enhancements of the order 103–104 for studies carried out on reference laboratory dye components and unvarnished mock-paintings. Techniques including optical and scanning electron microscopy were used to monitor the drying of the film and its resulting morphology, as well as to map the distribution of silver nanoparticles in the film so as to account for any visual modification to the underlying surface upon film removal. Copyright © 2011 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy, 2009
Resonance Raman spectroscopy has been utilized to identify vegetal and animal dyes and lakes. The... more Resonance Raman spectroscopy has been utilized to identify vegetal and animal dyes and lakes. These compounds have been used by artists since antiquity, and their identification has important implications in art history and conservation. The resonance condition is useful when working with real ancient objects so as to enhance the Raman scattering of chromophores with respect to the strong signal of the matrix, such as the textile or parchment over which the colorant is supported. The strong fluorescence that generally characterizes the resonance Raman spectra was eliminated by using subtracted shifted Raman spectroscopy (SSRS). A systematic study on reference organic dyes was primarily carried out to evaluate the suitability of the method and to estimate the strengths and limitations of the spectrum reconstruction process. The method was then applied to the noninvasive identification of madder on ancient dyed silk textiles such as an altar table cloth and a manutergium attributed to the Egyptian artistic textile production of the 10th-11th Century A.D.
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Papers by Costanza Miliani