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Compared to western wall paintings, the study, conservation and restoration of Far East Asian wall paintings is a more difficult task, owing not only to the varied supports and painting material constituents they are made of, but also to the particular social environments in which they are located and the consequences this has on the adopted theoretical and practical approaches to conservation. The recent availability of complementary non-invasive and micro-invasive analytical techniques led conservation scientists to have an increased interest in studying painting materials and techniques used in Far East Asian mural paintings. This chapter aims at presenting and discussing some of the most intriguing issues that conservation professionals are still confronted with. To this purpose, the chapter first introduces readers to the understanding of their material constitution and ancient painting techniques adopted with specific reference to plaster, preparation, paint layers and binding media and varnishes. Afterwards, the most advanced analytical approaches suitable for the achievement of a clear understanding of original schemes of polychromy, painting materials and technique are presented and discussed. This is of the outmost importance as the main issue when talking about Far East Asian mural painting conservation is the imminent risk of loss or damage.

The photoreduction of aqueous Ag+ to silver nanoparticles (AgNPs) on a substrate was studied aiming at the application of surface-enhanced Raman scattering (SERS) technique to the sensitive analysis of organic colorants directly on artworks. In particular, the presence of the synthetic dyes methyl violet (BV1) and fuchsine (BV14), in both standard and historical wool fibers, was analyzed. Scanning electron microscopy was employed to study the morphology and distribution of the NPs obtained on the fiber. We have carried out an investigation of the influence of several factors on the morphology of NPs: excitation wavelength, substrate, laser power and laser irradiation time. The resulting materials were analyzed at different laser wavelengths in order to evaluate the application range of the probe laser after the NPs formation. SERS spectra of the BV1 and BV14 dyes on the fiber were obtained and compared with those obtained in suspended conventional AgNPs, in order to deduce the possible influence of the wool substrate on the Raman spectra. SERS spectra were analyzed considering the possible resonance Raman processes. Bands attributed to the protein substrate were also identified. The main goal of this work was to assess and optimize a general method of analysis of organic dyes on natural fibers based on the direct preparation of AgNPs by laser SERS technique. Copyright © 2017 John Wiley & Sons, Ltd.

In the field of applied researches in heritage science, the use of multivariate approach is still quite limited and often chemometric results obtained are often underinterpreted. Within this scenario, the present paper is aimed at disseminating the use of suitable multivariate methodologies and proposes a procedural workflow applied on a representative group of case studies, of considerable importance for conservation purposes, as a sort of guideline on the processing and on the interpretation of this FTIR data. Initially, principal component analysis (PCA) is performed and the score values are converted into chemical maps. Successively, the brushing approach is applied, demonstrating its usefulness for a deep understanding of the relationships between the multivariate map and PC score space, as well as for the identification of the spectral bands mainly involved in the definition of each area localised within the score maps.

InthispapersomecoloredframescomingfromtheverypopularcinematographicfilmSardinianDrummerBoy,datingbacktothebeginning of the XX century, were analyzed. The presence in the emulsion of silver nanoparticles (AgNPs), which are formedthanks to the impression–development mechanism, confers to the cinematographic film the characteristic of being an efficientSurface Enhancement Raman Spectroscopy (SERS) substrate. This peculiarity makes it possible to investigate, in a non-invasiveway, the nature of the film components, such as the dyes used for the coloring process. In particular, Raman analyses allowedthe unambiguous identification of the dyes used in tinted frames, i.e. tartrazine and safranin, in which the colorant is absorbedby the gelatin, and intoned frames, i.e.Rhodamine B, wherethe dyeisfixed thankstothe formationofaninsolublespecies withAgIobtainedbyconversionofmetallicsilver.Thissecondcaseisofparticularinteresttoevaluatethepossibilitytoidentifythedyeeven when it is present as a silver iodide derivative. For this purpose an AgI-colorant derivative has been prepared and its SERSspectrum compared with that obtained on the film sheet. Copyright © 2015 John Wiley & Sons, Ltd.Additional supporting information may be found in the online version of this article at the publisher’s web site.Keywords: cinematographic film; tinting; toning; SERS; dyes

Analytical investigations were aimed at providing the wall painting conservator with information related to the painting materials’ constitution with particular reference to the identification of binding media, pigments and lime, and cement covering applied on the occasion of previous restoration interventions. Elemental, molecular spectroscopic (μFTIR, μRaman), and immunochemical methods applied directly on the paint cross-sections were used to characterize and spatially locate each paint component.

The present research is focused on the setting up of an advanced analytical system for the detection of synthetic dyes. The system is based on the combination of an innovative thin layer chromatography (TLC) plate coupled with enhanced infrared (MU-ATR, metal underlayer attenuated total reflection) and Surface Enhanced Raman (SERS) spectroscopy. In particular, a TLC plate made of silver iodide (AgI) applied onto a gold coated glass slide (AgI@Au) is proposed as an efficient stationary phase for the separation of dyes mixtures. The separated dyes are then identified by means of both enhanced FTIR and SERS, performed directly on the same eluted spots. The use of a mid-IR transparent inorganic salt as stationary phase coupled with the underneath gold layer avoids spectral interferences, enhancing the signal obtained from ATR analyses. At the same time, SERS spectra can be recorded as the TLC plate may act as a SERS active substrate due to the photoreduction of AgI to metallic Ag caused by the exposure to the laser during the Raman analysis. Different mixtures of synthetic dyes of known composition, widely used in dyeing processes, have been tested and the method resulted to be effective in identifying trace amounts in the order of tens nanograms. Moreover, the method has been further evaluated on a real case study represented by dyes extracted from dyed wool.

The identification of organic dyes is a challenging task in all the fields such as the forensic and conservation sciences, especially in cases where the amount of sample is extremely small. In this paper we propose a new enhanced FTIR method (MU-ATR metal underlayer ATR spectroscopy), which we believe is the first of its kind, for the analysis of a few ng of dyes. With this method, dyed fiber micro-extracts can be analyzed using a commercial FTIR microscope with a fixed incident angle, obtaining the same separation between the different classes of dyes investigated as we obtained analyzing pure dyes in transmission mode. Moreover, the new enhancement method has been validated on a real sample dated back to the 1893, showing how it can be promising for the analysis of trace amounts of organic substances in artistic samples such as dyes in paintings or textiles, varnishes and organic residues on archaeological objects.

none 8 si To study degradation processes occurring on painting materials, the use of high-resolution micro-analytical techniques is highly requested since it provides a detailed identification and localisation of both the original and deteriorated ingredients. Among the various pigments recently studied, the characterisation of verdigris has received a major interest. This pigment has not a unique chemical formula, but its composition depends on the recipe employed for its manufacturing. Moreover, verdigris paints are not stable and are subject to a colour change from blue-green to green, which occurs in the first few months after the application. In this paper, we focused our attention on the use of ATR-FTIR mapping as a useful method to identify verdigris secondary products and pathways. Several mock-ups and real samples have been analysed, and the correlation among the detected compounds and their spatial location, obtained by the application of ATR-FTIR microscopy in mapping mode, allowed formulating some hypotheses on the degradation pattern of verdigris, which may feed the discussion on the transformation and stability of this pigment. From an analytical point of view, we showed how FTIR mapping approaches may be extremely useful both for the identification of compounds in complex matrix in which single spectra may limit the exhaustive characterisations due to bands overlapping and for the study of degradation pathways by taking into consideration the relative distribution of degradation products. Prati, S; Bonacini, I.; Sciutto, G.; Genty-Vincent, A.; Cotte, M.; Eveno, M.; Menu, M.; Mazzeo, R. Prati, S; Bonacini, I.; Sciutto, G.; Genty-Vincent, A.; Cotte, M.; Eveno, M.; Menu, M.; Mazzeo, R.

We present an overview of recent advances in the application of Fourier Transform Infrared (FTIR) microscopy for analysis of complex, multicomponent, and multilayer samples such as those typically encountered in the field of heritage materials. This technique is particularly useful since it allows identification and localization of both organic and inorganic (if IR active) compounds. New improvements have been possible thanks to the introduction of ad hoc sample preparation methods to obtain either thin or cross sections that allow both avoidance of contamination from organic embedding resin and improvement of the quality of the acquired spectra. Moreover, integrated use of spectra registered in the near-infrared (NIR) and mid-infrared (MIR) regions allows better comprehension of cross section composition. Data interpretation has been improved thanks to the development of chemometric methods for elaboration of hyperspectral data. A new and very promising field is the development of enhanced FTIR methods for detection of trace components in microextracts. These systems, allowing detection of extractable organic compounds from about 0.1 mg of sample, will be extremely useful in the future for analysis of natural and synthetic colorants, varnishes extracted, for instance, from cotton swabs used during cleaning of paintings, and organic residues on archeological remains.

The analysis of dyes in cultural heritage samples is a well-known challenging task, due to their inherent high tinting strength and consequent low concentration in the carrying matrix a fact that severely limits the number of analytical techniques that can be efficiently and micro-destructively employed for their detection and unambiguous identification. In the present study, an advanced and alternative SEIRA based analytical protocol for the analysis of small quantities of synthetic colorants has been proposed. The method has been set up for the identification of Acid Orange 7 (AO7) using Au nanoparticles obtained by laser ablation in solution (LASiS). Analyses have been performed applying a drop containing a mixture between the colorant and the Au colloidal solution in its unaggregated state on a gold coated glass slide for RAS (Reflection Absorption Spectroscopy) analysis. The first results showed that, thanks to the enhancement produced by the nanoparticles, it is possible to analyze small amount of diluted solutions containing the colorant. Thus, the method has been successfully applied for the analysis of few pieces of dyed wool, after the development of a suitable micro extraction procedure.

The present research was aimed at exploiting and evaluating the potentialities of FT-NIR microscopy, as a complementary approach to analysis in the MIR region, for the chemical characterisation of paint cross sections. Even if FT-NIR technique is still underutilised in the field of cultural heritage investigations, the integrated use of information recorded in the NIR and in the MIR regions proved to be extremely useful in the molecular investigation of organic and inorganic substances. In fact, combination and overtone bands present in the NIR region, even if weaker and less selective than those in the MIR region, are not distorted by reflection phenomena. Furthermore, NIR spectra can be efficiently used as a spectral fingerprint for the stratigraphic characterisation of paint cross sections. The proposed analytical protocol was applied on two historical samples, presenting different stratigraphic structures. Suitable chemometric methods were applied for the elaboration of multivariate chemical maps recorded in the range 700–7500 cm − 1 . In particular, a comprehensive and efficient procedure based on an interactive brushing approach, which combines the structural information of the score scatter plots with the spatial information of the PC score maps, was used. Interestingly, NIR data allowed a thorough characterisation of paint structures, providing information for the identification of components and suggesting the differentiation among different types of proteins. Moreover, NIR spectra permitted to achieve an efficient distinction of different classes of natural resins, demonstrating that, even working at a microscopic level, the NIR region may support the identification of different terpenoid materials. Multivariate analysis performed on MIR data did not provide satisfactory results, probably due to the distortion of the spectra and overlapping of bands. Nevertheless, MIR outcomes were investigated to support the interpretation of NIR spectra and in attempt to define an integrated protocol for the characterisation of complex paint mixtures.

The role of lipids in controlling water exchange is fundamentally a matter of molecular organization. In the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. The analysis of molts from four snake species: tiger snake, Notechis scutatus, gabon viper, Bitis gabonica, rattle snake, Crotalus atrox, and grass snake, Natrix natrix, revealed correlations between the molecular composition and the structural organization of the lipid-rich mesos layer with control in water exchange as a function of temperature. It was discovered, merging data from micro-diffraction and micro-spectroscopy with those from thermal, NMR and chromatographic analyses, that this control is generated from a sophisticated structural organization that changes size and phase distribution of crystalline domains of specific lipid molecules as a function of temperature. Thus, the results of this research on four snake species suggest that in snake skins different structured lipid layers have evolved and adapted to different climates. Moreover, these lipid structures can protect, "safety", the snakes from water lost even at temperatures higher than those of their usual habitat. © 2013 Elsevier Inc. All rights reserved.

If compared to western wall paintings, the study, conservation and restoration of far east Asian wall paintings is a more difficult task, owing not only to the varied supports and painting material constituents they are made of, but also to the particular social environments in which they are located and the consequences it has on the adopted theoretical and practical approaches to conservation. For instance, in some countries an element of devotion and the desire to offer the best to the gods leads religious communities to rebuild damaged sections of structures instead of trying the preserve them. Therefore, when talking about far east Asian mural paintings conservation the main issue is their imminent risk of loss or damage. This has sometime led to certain standardization of treatments (pigments, consolidants, protective coatings and industrial products) as it happened, for example, with external architectural polychromies where the need to identify alternative treatments for conserving exterior surfaces that have retained a reasonable amount of historical material is of the outmost importance. Consequently further scientific research on traditional materials, techniques and skills would be desirable and could continue to improve the results in the future. In this regard collaborative studies on the subject of far east Asian architectural polychromy at the international level should be encouraged and implemented.