Fiber Optic Reflectance Spectroscopy Research Articles

Multianalytical non-invasive characterization of phthalocyanine acrylic paints through spectroscopic and non-linear optical techniques.

The documentation and monitoring of cleaning operations on paintings benefit from the identification and determination of thickness of the materials to be selectively removed. Since in artworks diagnosis the preservation of the object's integrity is a priority, the application of non-invasive techniques is commonly preferred. In this work, we present the results obtained with a set of non-invasive optical techniques for the chemical and physical characterization of six copper-phthalocyanine (Cu-Pc) acrylic paints. Cu-Pc pigments have been extensively used by artists over the past century, thanks to their properties and low cost of manufacture. They can also be found in historical paintings in the form of overpaints/retouchings, providing evidence of recent conservation treatments. The optical behaviour and the chemical composition of Cu-Pc paints were investigated through a multi-analytical approach involving micro-Raman spectroscopy, Fibre Optics Reflectance Spectroscopy (FORS) and Laser Induced Fluorescence (LIF), enabling the differentiation among pigments and highlighting discrepancies with the composition declared by the manufacturer. The applicability of Non Linear Optical Microscopy (NLOM) for the evaluation of paint layer thickness was assessed using the modality of Multi-photon Excitation Fluorescence (MPEF). Thickness values measured with MPEF were compared with those retrieved through Optical Coherence Tomography (OCT), showing significant consistency and paving the way for further non-linear stratigraphic investigations on painting materials.

Probing some organic ukiyo-e Japanese pigments and mixtures using non-invasive and mobile infrared spectroscopies.

Non-invasive identification of organic colourants in paintings still remains a challenging issue, especially in the case of extremely thin layers of paint on printed paper such as Japanese ukiyo-e prints. Because prints are fragile artworks, various non-invasive analytical methods need to be employed. The present work focuses on results obtained by combining fibre optic reflectance spectroscopy in the near-infrared range (FORS NIR) with mid-infrared (MIR) spectroscopy. The first step consists of identifying spectroscopic marker bands typical of some organic pigments (indigo, gamboge, cochineal, turmeric, safflower, dragon's blood). Some reference printouts involving paper substrate, binder and pigments (seldom used or as mixtures) were then investigated in order to establish a straightforward way to extract the marker bands of the pigments. Some data post-treatments were applied to the spectra, such as spectral subtraction, in order to abstract the signal from overlapping bands originating from both substrate and binder, and second derivative calculation to emphasise the pigment marker bands' frequency positions. These data treatments turned out to be relevant to extract information on the organic pigments of interest, even within complex mixtures.

Sanguine Paint: Production, Characterization, and Adhesion to the Glass Substrate

ABSTRACTFor centuries, the only painting materials used in stained-glass production were grisaille and yellow (silver) stain. At the end of the fifteenth century, stained-glass painters began to use a new material, sanguine. This paint is mainly produced with iron oxide particles, usually haematite, and allowed to obtain a colour that can vary from yellowish to brownish-red due to the nature and particle size of the iron oxide. A translucent sanguine was mostly applied as flesh and hair colour, with an opaque sanguine used for drapery, architectural motifs, and heraldry. The main goal of this study is to investigate the relationship between historic sources on the preparation and use of sanguine from the fifteenth to the nineteenth centuries and the evolution evidenced in the recipes regarding the production method. Representative recipes from several centuries (sixteenth to nineteenth centuries) were selected and reproduced for this study. These reconstructions were thoroughly characterized using X-ray powder diffraction, optical microscopy (OM), and fibre optic reflectance spectroscopy (FORS). The OM and FORS data were correlated with historic sanguine paints applied on historic stained-glass. The similarities and differences between historic and reconstructed paints are presented. The study of reconstructed sanguine’s adhesion to glass using cross-cut testing was also performed, revealing that the adhesion is strongly influenced, not only by the binder, but also by the composition and morphology of the sanguine paint.

Non-invasive study of natural dyes on historical textiles from the collection of Michelangelo Guggenheim

A selection of historical textile fragments from the Venetian art dealer Moisè Michelangelo Guggenheim collection, ranging from XV to XVIII century, has been investigated by means of non-invasive techniques in order to reveal the coloring materials. Imaging was preliminarily used to visually investigate the selected artwork fragments in order to investigate their structure and conservation conditions; Fiber Optics Reflectance Spectroscopy (FORS) allowed recognizing the main natural dyestuffs, such as indigotin and anthraquinones-based compounds, except the yellow ones, difficultly identifiable when using this non-invasive technique. Collected spectroscopic data have been also elaborated by using a clustering algorithm that permitted to group collected spectra on the basis of similar properties and evidencing their inflection point wavelength as the most influencing feature.

There’s more to reflectance spectroscopy than lux

Fibre-optic reflectance spectroscopy is widely used as a tool for the analysis of coloured materials such as pigments and paints. We describe a new design for a FORS probe which is held some 5cm away from the sample surface and interrogates a spot of 2mm diameter, offering a significant advantage over existing methods. The spectrometer employs an illuminance of 1250lux, equivalent to 0.5mWcm−2 averaged across the visible spectrum. The spectral measurements take less than a second ensuring that the risk of sample photodegradation is minimal. Under these conditions there is no detectable temperature rise of the illuminated area. Increasing the illuminance above 25mWcm−2, a light level significantly higher than that required for our measurements, gave rise to significant localised temperature rises in model manuscripts. This demonstrates the need for caution when using this technique for the analysis of precious heritage items.

Use of integrated non-invasive analyses for pigment characterization and indirect dating of old restorations on one Egyptian coffin of the XXI dynasty

The Royal Museums of Art and History of Brussels holds six coffins of the 21st Dynasty coming from a single discovery, the Second Cachette of Deir el-Bahari (Bab el-Gasus) (L. Delvaux & I. Therasse, Sarcophages. Sous les étoiles de Nout, Bruxelles 2015, p. 83–111). Since their discovery in 1891, their rich decorations have been subjected to deep manipulations during the years. In 2014, six coffins and four mummy-covers, the entire collection of the 21st Dynasty, were entrusted to the European Institute of Restoration for their diagnosis and restoration. In 2015, one compete coffin (composed by the external coffin, the internal one and the mummy cover) were the subject of a first targeted diagnostic campaign at the European Institute of Restoration laboratories.On this occasion, non-invasive in situ analyses have been performed on more than one hundred measuring points of the complete object, considering the five decorated parts (the two wooden anthropoid coffins composed by lid and base and the mummy-cover) showing both different technical features and pictorial materials.After a preliminary phase of analysis by imaging techniques such as Infrared Reflectography and Visible Fluorescence induced by UV, the pigments and binders were examined exploiting the synergy between four complementary techniques, namely EDXRF (energy dispersive X-ray fluorescence), FORS (fibre optics reflectance spectroscopy), reflection FTIR (Fourier transform infrared spectroscopy) and micro-Raman spectroscopy. The application of techniques with different penetration depths on more than one hundred points allowed to detect the stratigraphic sequences without sampling, opening to the interesting application to off-limits masterpieces.Based on imaging techniques, the painted surfaces showed areas with different features: dark areas with no UV fluorescence and low reflectance in IR, bright UV fluorescence and high IR reflectance (wavelength>700nm) and low-intensity UV fluorescence again with high reflectance in the infrared region. Such zones can be linked to the presence or absence of marker chemical elements (for instance Ba or Ti) or compounds that give hints about the presence and the period of the restorations. In these areas, an overlapping of a modern layer on the ancient and original one is the most probable current status of the pictorial stratigraphy.Original identified pigments include Egyptian blue, copper-based green, calcium carbonate and Red Ochre on an underlying Orpiment yellow layer. In the areas considered as already restored in the past on the bases of the analytical results, we find Azurite, Prussian blue, Egyptian Blue, Vermillion, Red Ochre, Chrome Red, Chrome Green, copper-based green, Zinc Yellow and Lead White. A layer composed of a natural resin was also detected by in-situ FTIR measurements; the resin could be more precisely identified as mastic by laboratory analyses.

Barium, zinc and strontium yellows in late 19th\u2013early 20th century oil paintings

This work focuses on the study of the 19th century yellow chromate pigments based on barium (BaCrO4), zinc (4ZnCrO4·K2O·3H2O) and strontium (SrCrO4). These pigments, which are reported to shift in hue and darken, have been found in 19th century artworks. A better understanding of their historic manufacture will contribute to the visual/chemical interpretation of change in these colours. Research was carried out on the Winsor & Newton (W&N) 19th century archive database providing a unique insight into their manufacturing processes. One hundred and three production records were found, 69% for barium, 25% for zinc and 6% for strontium chromates, mainly under the names Lemon, Citron and Strontian Yellow, respectively. Analysis of the records shows that each pigment is characterised by only one synthetic pathway. The low number of records found for the production of strontium chromate suggests W&N was not selling this pigment formulation on a large scale. Furthermore, contrary to what the authors have discovered for W&N chrome yellow pigments, extenders were not added to these pigment formulations, most probably due to their lower tinting strength (TS). The latter was calculated in comparison to pure chrome yellow (PbCrO4, 100% TS) resulting in 92% for barium, 65% for zinc potassium and 78% for strontium chromate pigments. This indicates that W&N was probably using extenders primarily to adjust pigment properties and not necessarily as a means to reduce their costs. Pigment reconstructions following the main methods of synthesis were characterised by complementary analytical techniques: Fibre optic reflectance spectroscopy, X-ray diffraction, micro-Raman and micro-Fourier transform infrared spectroscopies. These pigments can be clearly distinguished on the basis of their infrared CrO42− asymmetric stretching fingerprint profile (between 1000 and 700 cm−1) and of their Raman CrO42− stretching bands (850–950 cm−1). This enabled their identification in historic paint samples: a tube of late 19th century W&N Lemon Yellow oil paint and micro-samples from paintings by three Portuguese painters, António Silva Porto (1850–1893), João Marques de Oliveira (1853–1927) and Amadeo de Souza-Cardoso (1887–1918). The good correlation found between the reconstructions and historic samples validates their use as reference materials for future photochemical studies.

Identifying eighteenth century pigments at the Bodleian library using in situ Raman spectroscopy, XRF and hyperspectral imaging

There are multiple challenges in analysing pigments in historic watercolour paintings on paper, and typically non-invasive, in situ methods are required. Recent developments in portable analytical instrumentation have made this more accessible to heritage institutions, but many commercial systems are not optimised for the specific requirements of manuscripts and works on paper. This paper describes the successful use of Raman spectroscopy, X-ray fluorescence spectroscopy (XRF) and hyperspectral imaging to identify and map watercolour pigments used by the eighteenth century botanical illustrator, Ferdinand Bauer, and demystify the unusual colour code system found in his sketches. The value, delicate nature and large size of these paintings necessitated the use of using in situ, non-contact methods of analysis. A portable, bespoke Raman spectrometer specifically designed for analysing pigments from works on paper was used together with a bespoke portable Fibre optic reflectance spectrometer, portable X-Ray Fluorescence spectrometer and a hyperspectral imaging sensor. The results demonstrate that although there is a significant compromise between achieving good Raman spectroscopic results from artists’ pigments and using sufficiently low laser power densities so as not to cause damage to the pigments, good results could be obtained with this portable system, particularly when combined with XRF, fibre optic reflectance spectroscopy (FORS) and hyperspectral imaging. Eight pigments were identified unequivocally from 125 watercolour paintings analysed, suggesting that Bauer used a more traditional and more limited palette than previously considered, and that his palette changed significantly in his later paintings. Similar pigments identified by the authors on colour chart that was discovered in 1999 in Madrid and attributed to Bauer, add weight to the attribution of this chart to Bauer. The data provides a much deeper insight into Bauer’s colour annotations, and how he was able to achieve such an impressive degree of colour fidelity in his work.

The role of different network modifying cations on the speciation of the Co2 + complex in silicates and implication in the investigation of historical glasses

In the last decades the speciation of the cobalt complex in a glass matrix has been extensively studied. Bivalent cobalt ions in glasses of different composition commonly adopt a tetrahedral coordination, though hexa- or penta-coordinated species are also possible. Changes in the absorbance spectrum of Co-doped glasses were attested in previous studies according to the introduction of different modifying cations. A shifting of the first sub-band characterizing the typical triplets of tetrahedral Co2+ ions in both the visible and near infrared regions was observed, but discrepancies in literature suggested a relevant role of glass composition on the definition of the optical signature of cobalt. Co-doped glasses with different composition (soda-lime, potash-lime, mixed alkali and ZnO-Na2O-CaO-SiO2) were studied via Fiber Optic Reflectance Spectroscopy (FORS). Pseudo-Voigt functions were used for the deconvolution of the absorbance spectra and the features of the bands characteristic of each cobalt complex were investigated. The structural role played by each modifying cation and the fundamental implications of glass basicity on the speciation of different Co-complexes were stressed. Changes in glass structure resulted in different equilibria between the three absorbing species whose specific optical signatures in the 480–530nm region interact to determine the resulting absorbance spectrum.

Pigments & dyes in a collection of medieval illuminations (14th–16th century)

AbstractThe Marcadé Collection (Bordeaux Cathedral treasury) consists among other objects of 42 illuminations (14th to the 16th century) from five origins (France, Italy, Germany, the Netherlands, and Spain). For better knowledge of these miniatures, the pigments and dyes have been analyzed in ten illuminations chosen in order to represent the diversity of the collection. The aim of this study is to establish a panorama of the pigments and techniques used in medieval miniatures through the study of a set of manuscripts and to discuss the potentialities of the analytical techniques in order to reach this objective. Hyperspectral imaging is a rapid, mobile and noninvasive technique. It gives reflectance spectra for each pixel of the image. The datacube obtained was treated in order to visualize images and reflectance spectra. The software allows the mapping of the pigments by comparing spectra with those of our database. As some interpretation difficulties can appear for dyes or mixtures, to confirm the identification, point techniques such as Raman, X‐ray spectroscopy, and Fiber Optic Reflectance Spectroscopy in the Near Infrared range were used. Analyses allowed access to the palette for each illumination and showed the colours diversity and pigments treatment. They increase knowledge about the materials used and the evolution of them during the time period: the use of dyes and shell gold became more important at the end of the period. The analytical choice respects the fragility and preciousness of these artworks and helps the fast data acquisition for the materials identification.

Chemical characterization of black and red inks inscribed on ancient Egyptian papyri: The Tebtunis temple library

This article presents the results of a study on the chemistry of the black and red inks used on papyri from the only institutional library to survive from ancient Egypt – the Tebtunis temple library. The aim of the study is to identify, through the chemistry of the inks, if certain papyrus fragments from the library are related. The papyri are examined using non-invasive analytical methods, including optical microscopy, X-ray fluorescence (XRF) spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDXS), Raman spectroscopy and fiber optics reflectance spectroscopy (FORS). Via these techniques, inks undocumented in the analytical record are detected. Moreover, the analytical results are compared to other assemblages of ancient manuscripts from the Hellenistic and Roman periods (c. 200BCE–400CE) and provide new information on the history of the production of ink in the ancient Mediterranean cultures.

An in situ non-invasive study of two Tibetan manuscripts from the Asian Collection of the Museum of Natural History in Florence

In the complex and multiform panorama of the Asian heritage, Tibetan Buddhist sacred texts are tangible evidence of an ancient religious tradition. The historical value and fragility of these unique and priceless works of art, together with an increased awareness of the importance of preserving our cultural heritage, has prompted the use of non-invasive analytical techniques to the study of these ancient religious items. In particular, the present work aims to characterize inks and pigments of two ancient Tibetan manuscripts part of the collection of the Museum of Natural History, Department of Anthropology, in Florence (IT). A combination of portable microphotography, X-ray fluorescence (XRF), and UV-Vis-NIR fiber optic reflectance spectroscopy (FORS) was used for in situ investigation of all the most significant painted area appearing in the manuscripts. Information about the preparatory substrate, the pigments, and the metal inks were gained. A step forward a better understanding of the working methods applied by the artists was made, thus contributing significantly towards the planning of the most appropriate conservation-restoration procedures.

Characterization of Yellow and Red Natural Organic Colorants on Japanese Woodblock Prints by EEM Fluorescence Spectroscopy

As part of a project designed to systematically identify colorants on Japanese woodblock prints, excitation–emission matrix (EEM), or three-dimensional, fluorescence spectroscopy, equipped with a fiber optic probe, was used to characterize natural yellow and red organic colorants on 18th-century Japanese prints without taking samples. This analysis technique collected emission spectra in the visible region for a sequence of excitation wavelengths at 10 nm steps from 250 to 600 nm. The resultant data set provided characteristic excitation/emission patterns that were used to identify several natural colorants, including safflower, madder, sappanwood, gamboge, flavonoids, berberines, and turmeric. In combination with other non-sampling methodologies, including x-ray fluorescence and fiber optic reflectance spectroscopy, most colorants on the prints were quickly and non-destructively characterized. Based on examination of 213 prints, several patterns of colorant use were observed. The prints often contained more than one yellow, red, or blue colorant. From 1781 to 1801, considered the Golden Age of the Japanese print, it was common to find multiple types of yellows, reds, and blues on a single print. The colorant madder was identified on many of the prints, while gardenia and berberine-containing dyes were found on none. This paper presents the theory, experimental parameters, and limitations of the EEM fluorescence technique. The technique is illustrated using the analysis results of four Japanese woodblock prints.

Export Chinese blue-and-white porcelain: compositional analysis and sourcing using non-invasive portable XRF and reflectance spectroscopy

The chemical composition of Chinese blue-and-white porcelain, from the body to the pigment and the glaze, has been widely investigated over the last decades. However, most studies focused on ware from official kilns and much less attention has been given to folk kilns whose production was primarily aimed at supplying overseas markets. Moreover, scientific analysis has often relied on sophisticated laboratory-based instrumentation, a methodology that can be used neither for large sets of archaeological sherds nor in the field. The research presented here evaluates the applicability of non-invasive portable X-ray fluorescence (pXRF) and fiber optics reflectance spectroscopy (FORS) for the study of overseas Chinese blue-and-white porcelain manufactured in Jingdezhen and Zhangzhou, the main production centers during the late 16th to early 17th centuries. Results obtained on a limited number of sherds found in Indonesia and the Philippines show that concentration levels of some minor and trace elements, in particular zirconium and associated thorium, are sufficient to clearly distinguish Jingdezhen and Zhangzhou productions. The composition of the cobalt-based blue pigment was also easily identified with pXRF, highlighting the Fe-poor and Mn-rich compositional pattern in accordance with the local asbolite ores used during this time period. Furthermore, FORS provided additional information on tint and shade variations of the blue pigment. Consequently, pXRF combined with FORS represents an innovative and cost effective analytical approach to study the chemistry and provenance of Chinese blue-and-white porcelain, particularly in the field and/or for large archaeological sherd collections.

Identification of natural red and purple dyes on textiles by Fiber-optics Reflectance Spectroscopy

Understanding dye chemistry and dye processes is an important issue for studies of cultural heritage collections and science conservation. Fiber Optics Reflectance Spectroscopy (FORS) is a powerful technique, which allows preliminary dye identification, causing no damage or mechanical stress on the artworks subjected to analysis. Some information related to specific light scattering and absorption can be obtained in the UV–visible and infrared range (300–1400nm) and it is possible to discriminate the kind of support fiber in the near infrared region (1000–2500nm). The main spectral features of natural dye fibers samples, such as reflection maxima, inflection points and reflection minima, can be used in the differentiation of various red natural dyes. In this work, a set of dyed references were manufactured following Mexican recipes with red dyes (cochineal and brazilwood) in order to determine the characteristic FORS spectral features of fresh and aged dyed fibers for their identification in historical pieces. Based on these results, twenty-nine indigenous textiles belonging to the National Commission for the Development of Indigenous People of Mexico were studied. Cochineal and brazilwood were successfully identified by FORS in several pieces, as well as the mixture of cochineal and indigo for purple color.

Optical measurements of paintings and the creation of an artwork database for authenticity.

Paintings have high cultural and commercial value, so that needs to be preserved. Many techniques have been attempted to analyze properties of paintings, including X-ray analysis and optical coherence tomography (OCT) methods, and enable conservation of paintings from forgeries. In this paper, we suggest a simple and accurate optical analysis system to protect them from counterfeit which is comprised of fiber optics reflectance spectroscopy (FORS) and line laser-based topographic analysis. The system is designed to fully cover the whole area of paintings regardless of its size for the accurate analysis. For additional assessments, a line laser-based high resolved OCT was utilized. Some forgeries were created by the experts from the three different styles of genuine paintings for the experiments. After measuring surface properties of paintings, we could observe the results from the genuine works and the forgeries have the distinctive characteristics. The forgeries could be distinguished maximally 76.5% with obtained RGB spectra by FORS and 100% by topographic analysis. Through the several executions, the reliability of the system was confirmed. We could verify that the measurement system is worthwhile for the conservation of the valuable paintings. To store the surface information of the paintings in micron scale, we created a numerical database. Consequently, we secured the databases of three different famous Korean paintings for accurate authenticity.

Investigation on water content in fresco mock-ups in the microwave and near-IR spectral regions

Water diffusion inside masonry is responsible for the majority of the decay phenomena observed in wall paintings and frescos. Thus, the diagnostics of moisture and water content and their monitoring represent a key issue. In order to preserve the integrity of surfaces of artistic interest, investigations by means of non-destructive techniques (NDT) are preferred over others. The aim of this research is to determine methodologies to quantify the moisture content (MC) of frescos by means of the integrated use of two non-invasive techniques, namely fiber optic reflectance spectroscopy (FORS) in the near-IR region and evanescent field dielectrometry (EFD) in the microwave range. The FORS technique has been employed in order to assess the amount of water adsorbed from the surface by means of an analysis of the reflectance spectra in the Vis–NIR (350-2200 nm) range. This technique investigates the electronic and vibrational transitions that are characteristic of each compound and enables their identification. The water content is evaluated on the basis of the 1920 nm and 1450 nm absorption bands. The EFD system consists of a resonant probe connected to a network analyzer. The resonance frequency of the cavity under different moisture-content conditions of frescos is in the 1.0–1.5 GHz range. The device makes it possible to compute, in real time, the MC from a measurement of the transmission coefficient (amplitude versus frequency) through the probe. Fresco mock-ups have been prepared in collaboration with the Opificio delle Pietre Dure in order to recreate most of the possible chromatic shades obtained by mixing iron oxides and hydroxide-based pigments. Measurements were performed by employing both techniques on fresco models after wet-dry cycles obtained by means of poultices with a known water content. The results obtained with these two techniques were compared, and cross relationships between the EFD and FORS data were defined.

Time resolved laser induced fluorescence for characterization of binders in contemporary artworks

Abstract Contemporary artworks are often realized with multi-component mixtures with unknown compositions, which may be subjected to an unforeseeable degradation. A detailed characterization of these materials provides relevant information both to plan proper restoration strategies and to prevent damages. In particular, binders identification represents one of the major problems in the conservation of the contemporary works of art. In this paper, five binders routinely employed in contemporary paintings, i.e. acrylic resins, ethylene vinyl acetate, dammar varnish and linseed oil, were studied by Time Resolved Laser Induced Fluorescence Spectroscopy (TR-LIF). Experimental results confirm the TR-LIF analysis capability to isolate specific contributions from the investigated constituents. The spectral features of ten commercial paints containing the above mentioned binders were analyzed as well. In this latter case, additional diagnostic techniques, such as X-Ray Fluorescence Spectroscopy and Fiber Optics Reflectance Spectroscopy, were demonstrated to provide useful complementary information to integrate TR-LIF results.

Application of forensic photography for the detection and mapping of Egyptian blue and madder lake in Hellenistic polychrome terracottas based on their photophysical properties

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 π-π* 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.

Discovering “The Italian Flag” by Fernando Melani (1907–1985)

In the occasion of the celebrations for the 150th anniversary of the founding of Italy (1861–2011), it was decided to analyse the artwork “The Italian Flag” (La Bandiera Italiana) created by the artist Fernando Melani (Pistoia, 1907–1985), one of the precursors of the Poor Art artistic movement in Italy. This project is a follow-up to a previous study which was mainly focused on the pigments and dyes found in his home-studio.The main goal of this paper is to identify a correct diagnostic plan, based on the use of a combination of non-invasive and micro-invasive methodologies, in order to determine the state of preservation and define the best conservation procedures for a contemporary artwork.Visible, infrared and infrared false colour images as well as the Fibre Optic Reflectance Spectroscopy (FORS) technique were applied in situ to analyse The Italian Flag. Laser Induced Breakdown Spectroscopy (LIBS), Fourier Transform Infrared (FT-IR) and micro-Raman spectroscopies, Pyrolysis-Gas Chromatography/Mass Spectroscopy (Py-GC/MS), High Performance Liquid Chromatography with Diode Arrays Detection (HPLC-DAD) and Mass Spectrometric Detection (HPLC-ESI-Q-ToF) were all applied to three small samples detached from the three painted (green-blue, white and red-yellow, respectively) areas of the flag.The combination of the data obtained with all these techniques made possible a comprehensive understanding of both the chemical composition and physical behaviour of the materials used by the artist and supported curators in defining the preventive conservation of this artwork.