Paint Binder Research Articles

Co-occurrence of microplastics and microparticles containing Cu and Zn and other heavy metals in sea-surface microlayer in Osaka Bay, Japan

Antifouling biocides such as Cu, Zn, and organic compounds not only inhibit adhesion of sessile organisms on ship hull but also possess toxicity to non-sessile organisms in marine environment. Thus, we firstly investigated the heavy metals and polymer types of anthropogenic microparticles (MPs) floating in the sea-surface microlayer (S-SML) in Osaka Bay. 7 types of MPs containing different metals (Cu, Cu-Zn, Zn, Ti, Sn, Ba and Fe-Mn-Ni) were found. The polymer type for 97.8 % of Cu and Cu-Zn MPs (41 samples) and 52.6 % of Zn MPs (19 samples) was acrylic resins which are widely used as binders in contemporary antifouling paints for ships; concentrations of 511–54,000 mg/kg for Cu and 95.1–13,200 mg/kg for Zn were found in these MPs. The high metal concentrations found the co-existence of acrylic polymers point towards an origin from antifouling paint particles (APPs). Furthermore, to quantify Cu and Zn concentrations in these MPs based on X-ray fluorescence spectroscopy (μ-XRF), calibration curves obtained from standard paint particles containing different Cu and Zn concentrations and different particle sizes made with similar matrix used in commercial antifouling paint were firstly established, according to which highly reliable Cu and Zn concentrations in MPs were obtained.

Palaeoproteomic identification of the original binder and modern contaminants in distemper paints from Uvdal stave church, Norway

Two distemper paint samples taken from decorative boards in Uvdal stave church, Norway, were analysed using palaeoproteomics, with an aim of identifying their binder and possible contaminants. The results point at the use of calfskin to produce hide glue as the original paint binder, and are consistent with the instructions of binder production and resource allocation in the historical records of Norway. Although we did not observe any evidence of prior restoration treatments using protein-based materials, we found abundant traces of human saliva proteins, as well as a few oats and barley peptides, likely deposited together on the boards during their discovery in the 1970s. This work illustrates the need to fully consider contamination sources in palaeoproteomics and to inform those working with such objects about the potential for their contamination.

Unraveling the mummy's shroud: A multi-analytical study of a rare painted textile from Roman Egypt

This article describes a multi-analytical technical study of a rare painted shroud still wrapped around a female Egyptian mummy (MCABo EG 1974) in the collection of the Museo Civico Archeologico of Bologna, Italy. Long stored in the museum's warehouses, these mummified human remains were recently rediscovered within the Bologna Mummy Project (BOmp), an interdisciplinary endeavor promoted by the Museo Civico Archeologico and the Institute for Mummy Studies of Eurac Research, Bolzano, Italy. Dating to the Roman period (1st-2nd century C.E.), as confirmed by radiocarbon dating, this mummy displays a unique series of technical features, including the exceptional finding of a colorful painted shroud still preserved in its original location around the wrapped body, to which it is secured with textile straps and resin. In this context, scientific analysis aimed to deepen our current knowledge of the artistic practices of Roman Egypt through an in-depth study of the painting technique, context of production, and possible provenance of the mummy, while promoting a science-informed, enhanced approach to the preservation of the mummified human remains. This research relied on an integrated analytical protocol based on the combined use of imaging and mapping techniques, non-invasive point analysis, and micro-invasive investigation of minute samples, each carried out at the different partnering institutions. Computed tomography (CT) highlighted varying radio-densities for some of the flesh tones and red decorations. Visible photography and multiband imaging provided information on the nature and distribution of various materials on the surface. Fiber optics reflectance spectroscopy (FORS), X-ray fluorescence (XRF) spectroscopy, and Raman spectroscopy contributed to the characterization of the shroud's color palette along with optical microscopy (OM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), as well as high-performance liquid chromatography coupled with diode-array detection and mass spectrometry (HPLC/DAD and HPLC/MS). Materials detected include a limited number of mineral pigments and plant-derived dyes such as red lead, red ocher, madder, an unknown yellow dye, Egyptian blue and green, and a carbon-based black. Through access to MOLAB equipment and expertise, macro-XRF (MA-XRF), as well as combined X-ray diffraction (XRD) spot analysis and mapping, enhanced pigment identification. A combination of transmission Fourier-transform infrared (FTIR) spectroscopy with gas chromatography / mass spectrometry (GC/MS) was used to identify the paint binders and any additional organic substances possibly involved in embalming practices and ritual traditions, including animal fat, plant lipid, Pinaceae resin, gum, and beeswax. Mineralogical data gathered by XRD on surface deposits and soil residues collected from within the shroud's inner folds was crucial to put forward hypotheses, in support of the stylistic study of the shroud, concerning a possible provenance from Upper Egypt, most likely West Thebes. Both the shroud and inner bandages were found to be made with linen using OM. After undergoing scientific analysis and conservation treatment, the mummy was displayed in the “Mummies. Unwrapping the past” exhibition and was featured at the 10th World Congress on Mummy Studies, both held in Bolzano in the fall of 2022.

Egg vs. Oil in the Cookbook of Plasters: Differentiation of Lipid Binders in Wall Paintings Using Gas Chromatography-Mass Spectrometry and Principal Component Analysis.

Wall paintings are integral to cultural heritage and offer rich insights into historical and religious beliefs. There exist various wall painting techniques that pose challenges in binder and pigment identification, especially in the case of egg/oil-based binders. GC-MS identification of lipidic binders relies routinely on parameters like the ratios of fatty acids within the plaster. However, the reliability of these ratios for binder identification is severely limited, as demonstrated in this manuscript. Therefore, a more reliable tool for effective differentiation between egg and oil binders based on a combination of diagnostic values, specific markers (cholesterol oxidation products), and PCA is presented in this study. Reference samples of wall paintings with egg and linseed oil binders with six different pigments were subjected to modern artificial ageing methods and subsequently analysed using two GC-MS instruments. A statistically significant difference (at a 95% confidence level) between the egg and oil binders and between the results from two GC-MS instruments was observed. These discrepancies between the results from the two GC-MS instruments are likely attributed to the heterogeneity of the samples with egg and oil binders. This study highlights the complexities in identifying wall painting binders and the need for innovative and revised analytical methods in conservation efforts.

Reduction of polystyrene/polyurethane plastic wastes from the environment into binders for water-resistant emulsion paints

Waste management is fundamental to resource and environmental sustainability. Expanded polystyrene (EPS) and polyurethane (PU) waste plastics were recycled and applied as binder in emulsion paint formulation. The recycled polystyrene (rPS) and polyurethane (rPU) were blended into composite resins, where toluene was used as the solvent. The blends of rPS and rPU were optimized, while some physicochemical properties of the composite blends (rPS/PU) were evaluated. The results showed that the incorporation of rPU into rPS increased the viscosity (1818 mPa–3924 mPa), rate of gelation (dry-to-touch time: 15 min–0.25 min), moisture content (2.7%–8.1%), moisture uptake (3.2%–5.0%), solid content (48%–53.4%) and density (0.82 g/cm3 to 1.050.82 g/cm3) of the rPS/PU composite resins. Characterization was carried out using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and atomic force microscopy (AFM). The results summarily showed that there are interactions among the rPS and rPU molecules in the composite, where complimentary structural and morphological characteristics were also achieved. The composite resin also exhibited superior bond strength (0.5–4.24 Mpa) on wood, cast mortar, ceramic, and steel surfaces due to its stronger intra- and inter-surface interactions compared to the neat rPS resin. The composite resin was used as a binder in the formulation of emulsion paint. The paint exhibited stronger resistance to water, among other superior properties, when compared to the paints formulated using neat rPS and conventional polyvinyl acetate (PVA) resins. The reduction of plastic waste in this study holds potential for the production of highly water-resistant emulsion paint for outdoor and indoor applications.

New insight from MALDI-TOF MS and multivariate data analysis on the botanical origin of polysaccharide-based paint binders in ancient Egypt.

Polysaccharide-based materials of plant origin are known to have been used as binding media in paint and ground layers of artifacts from ancient Egypt, including wall paintings, cartonnages and sarcophagi. The use of gums from Acacia, Astragalus and Prunus genera has been suggested in the literature on the basis of their qualitative or quantitative monosaccharide profile after complete chemical hydrolysis. The introduction of partial enzymatic digestion of the polysaccharide material, followed by analysis of the released oligosaccharides by matrix assisted laser desorption ionization-time-of-flight mass spectrometry, has proved effective in discriminating among gums from different genera, as well as among species within the Acacia genus. In this study, the previously built Acacia database was expanded, principal component analysis (PCA) was used to aid in grouping of the samples, and data interpretation was refined following a modified acacieae taxonomy. Application of the analytical strategy to investigate the paint binders in artworks from ancient Egypt allowed qualitative discrimination of gums at a species level, and provided new insights into the artists' material choices.

Immunofluorescence microscopy for the characterization of paint binder in wall paintings: A two-step procedure of using anti-ovalbumin and anti-casein antibodies on the same micro sample

The aim of the study was to use immunofluorescence microscopy to identify two types of protein binders in 10 polished cross sections of micro samples, which were obtained from real and mock-up wall paintings. A two-step antibody hybridisation procedure was employed, in which the same micro samples were hybridised with anti-ovalbumin and subsequently with anti-casein antibodies and between the hybridisation steps, the sample's cross section was slightly re-polished and cleaned in order to remove all primary and secondary antibody remnants, which remained attached from the first hybridisation step (anti-ovalbumin). This allowed us to reduce the costs and operational difficulties, which are normally encountered, when antibodies, targeting two different proteins, are simultaneously mixed together. To reduce unspecific fluorescence, to amplify the fluorescence of the proteinaceous binders and to construct 3D surface topography models, apart from widefield fluorescence, laser-scanning confocal microscopy was performed. In parallel, FTIR spectroscopy analysis, of finding proteinaceous materials in micro sample cross sections, was also conducted. Results show that our two-step hybridisation procedure allowed for an accurate localisation of both types of proteinaceous binders without any interference from the first hybridisation step. Three micro samples proved positive for ovalbumin and one for casein and none of these proved positive for both analysed binder types. For eight micro samples, FTIR spectroscopy results completely matched those of immunofluorescence microscopy. According to our knowledge, this was the first immunofluorescence microscopy attempt of targeting two different types of proteins on the same cultural heritage micro sample.

Preparation and Testing of Anti-Corrosion Properties of New Pigments Containing Structural Units of Melamine and Magnesium Cations (Mg2+)

This paper deals with the properties and testing of newly prepared organic pigments based on melamine cyanurate containing magnesium or zinc cations depending on their composition and anticorrosive properties in model coatings. Organic pigments based on melamine cyanurate with Mg2+ in the form of a complex differing in the ratio of melamine and cyanurate units were prepared. Furthermore, a pigment based on melamine citrate with magnesium cation Mg2+, a pigment based on melamine citrate with magnesium cation, and a pigment based on melamine cyanurate with zinc cation were prepared. The properties of Mg-containing organic pigments were also compared with those of selected magnesium-containing inorganic oxide-type pigments. The above-synthesized pigments were characterized by inductively coupled plasma-optical emission spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction. In addition, the basic parameters that are indicative of the applicability of the pigments in the binders of anti-corrosion coatings were determined. The anti-corrosive properties of the tested pigments were verified after application to the epoxy-ester resin-based paint binder in three different concentrations: at pigment volume concentrations of 0.10%, 0.25%, and 0.50%. The anticorrosive effectiveness of pigmented organic coatings was verified by cyclic corrosion tests in a salt electrolyte fog (NaCl + (NH4)2SO4) in an atmosphere containing SO2 and by the electrochemical technique of linear polarization. Finally, the effect of the structure of the pigments on the mechanical resistance of the organic coatings was investigated. The results obtained showed that the new organic pigments exhibit anticorrosive properties, and at the same time, differences in performance were found depending on the structure of the pigments tested. Specifically, the results of cyclic corrosion tests and the electrochemical technique of linear polarization clearly demonstrated that synthesized pigments of the organic type based on melamine cyanurate containing magnesium or zinc cations ensure the anti-corrosion efficiency of the tested organic coatings. The highest anti-corrosion efficiency was achieved by the system pigmented with synthesized melamine cyanurate with magnesium cation (C12H16MgN18O6), whose anti-corrosion efficiency was comparable to the anti-corrosion efficiency of the tested inorganic pigment MgFe2O4, which was prepared by high-temperature solid-phase synthesis. In addition, these organic coatings achieved high mechanical resistance after being tested using the most used standardized mechanical tests.

Poly(Vinyl Acetate) Paints: A Literature Review of Material Properties, Ageing Characteristics, and Conservation Challenges.

Since their development in the 1950s, poly(vinyl acetate) [PVAc] paints (also known as vinyl) have been used by many artists, most notably in countries such as Spain, Portugal, and the United Kingdom; they are also used globally as a common binder for house paints. However, only a relatively limited number of heritage scientific studies have focused on vinyl paints. Consequently, many critical aspects of this material, such as the degradation processes, variations in paint formulations, and responses to conservation treatments, remain largely understudied. This article aims to summarise the available relevant information on poly(vinyl acetate) paints from both the scientific and the conservation practice perspectives. The article provides a brief overview of the development of poly(vinyl acetate) paints as artist-grade and household products and the known differences in their formulations. It also focuses on poly(vinyl acetate) ageing behaviour, the physicochemical properties, the recent scientific research on poly(vinyl acetate) material characterisation and degradation, and the main conservation issues regarding these paints, such as those relating to cleaning treatments.

Pigments and Binders Used in Bark Paintings by Aboriginal Artists from Across the Northern Territory and the Kimberly Region in Western Australia

ABSTRACT Bark paintings represent a unique artform that originated in Australia and continues to this day. This paper presents a scientific investigation into both the pigments and binders used by Aboriginal artists from across the Northern Territory (NT) and the Kimberley region in Western Australia (WA) and represents the first major study dedicated to identifying these materials in samples taken from paintings. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), Fourier transform infrared (FTIR) and Raman spectroscopy were used to identify the pigments in the four colors commonly associated with works by Aboriginal artists: red, yellow, black, and white. Iron oxides are used for red and yellow. Typically, kaolin is used for white and carbon or natural manganese ores are used for black, although the use of other pigments such as huntite (white) and battery black were seen in paintings from specific locations. Evidence of trade could not be established during this study; however, analysis shows that artists may use different pigments based on location and availability. A combination of FTIR and pyrolysis-gas chromatography-mass spectrometry (pyrolysis-GC-MS) was utilized to investigate the presence of a binder in the paint. Plant-based materials were identified as the binder in the majority of the paintings. The use of orchid juice was common, both as a preparatory layer on the bark substrate and as a paint binder. The presence of synthetic resins was more widespread than anticipated, attributed to both conservation efforts and more modern painting practices.

Predicting the mass spectrum of polymerizing linoleates using weighted random graph modeling

Biopolymers and biopolymer networks that form via autoxidation, like in drying of oil paint or fat degradation in food components, contain a large variety of monomeric building blocks. While the monomer variety complicates the modeling itself, obtaining experimental validation of infinite polymer networks is inherently difficult as well. A new model is developed, where an automated reaction network generation (ARNG) procedure is used to automatically generate the monomer components, structures and masses, and their reactions. This methodology is combined with random graph (RG) modeling to predict global polymer properties: distributions of numbers of monomer units and molar masses, gel point and gel fraction. This computational framework is applied to two model systems for linseed oil paint binder: the polymerization of ethyl linoleate (EL) and methyl linoleate (ML). A novel method was constructed to deal with the variability of monomer masses that complicates inferring molar mass from monomer number distribution. By modeling the polymer as a weighted random graph where the nodes contain information about the monomer masses in the system, the total weight of the finite connected components is computed. The predicted mass spectrum of finite connected components is used for validation with experimental data. A size exclusion chromatography (SEC) trace of ML is employed, which after calibration using the proposed framework, proves consistency between model and SEC data. The model provides a practical approach to both characterize complex biopolymers as polymers in terms of molar mass distribution and gel point, while preserving the information down to the level of monomeric units.

CNSL oxyacetic derivatives, new bio-based binders for paint preparation

The global coating industry produces tens of millions of metric tonnes of paints each year, and this quantity continues to grow. Most of these paints are obtained totally or partially from fossil resources, and many of them still use volatile organic compounds (VOCs) and/or other harmful chemicals. This paper describes the use of the cashew nutshell liquid (CNSL) as a raw material for synthesis of paint binders (sustainable materials). These binders are obtained in a single chemical step without tedious separation. These new bio-based materials (renewable resources) form stable films (green coatings) in a short drying time. The formulated paints are 100% aqueous, have low toxicity and ecotoxicity and require no additional drying agents or VOCs. Oxidative coupling of the alkylidene chain and addition of carboxylic acid to the carbon–carbon double bonds are implemented. The products obtained can be applied on different kinds of surfaces, such as glass slides, metal, wood or concrete, and exhibit good stability against various solvents and tropical conditions.

Flame-retardant performance of phosphorylated furan-containing alkyd resins

Over the past decade, with the emergence of environmental and human health concerns, research has focused on developing new solutions to replace fossil resources with more sustainable biobased resources. Furan derivatives can be obtained from plants, and their structures provide high resistance to high temperatures. Furan derivatives have been functionalized with phosphorus (P) to increase their fire-resistance properties. Thus, a new biobased bisfuran containing nitrogen and phosphorus (diethyl (((3-((((diethoxyphosphoryl)(hydroxy)(4-(hydroxymethyl)cyclopenta-1,3-dien-1-yl)methyl)amino)methyl)benzyl)amino)(hydroxy)(4-(hydroxymethyl)cyclopenta-1,3-dien-1-yl)methyl)phosphonate (HMF-MXDA-DEP)) was synthesized and used for the first time in polymerization to develop alkyd resins. The flame-retardant (FR) properties of these resins were studied. Alkyd resins are generally used as a binder in paint or varnish formulations. The use of a reactive FR during the polycondensation reaction of alkyd resins makes it possible to form covalent bonds and offer better durability over time. The impact of HMF-MXDA-DEP on film properties such as drying time, flexibility, adhesion and color was studied, and the thermal and FR properties were evaluated by differential scanning calorimetry, thermogravimetric analysis and pyrolysis–combustion flow calorimetry. Increased thermal stability and good FR properties of alkyd resins were demonstrated. In the cone calorimeter test, the lowest peak heat release rate (pHRR) was obtained with a coating of 2 wt% phosphorus HMF-MXDA-DEP on wood, and a 49% decrease in pHRR compared with that of FR-free alkyd resins was demonstrated.

A portable microfluidic device integrated with electrochemical sensing platform for detection of multiple binders in ancient wall paintings

The aging of the proteinaceous binders will cause the cultural relics to suffer from diseases such as flaking, cracks, and even peeling. Identifying the type of binders in a timely manner is conducive to restore diseased cultural relics. High-throughput and portable detection system are of great significance for researching cultural relic materials on the archaeological site. Therefore, in this work, a portable electrochemical microfluidic device for the simultaneous detection of casein, ovalbumin, and peach gum binders was developed. The proposed electrochemical immunosensor technology integrated with microfluidic device achieve the goals of miniaturization, portability and reagent-saving. For casein, ovalbumin and peach gum, excellent performance was obtained in terms of their limits of detection (LOD) at 0.237, 0.507, and 0.403 ng mL−1 (S/N = 3), respectively. In addition, the microfluidic sensing platform exhibited acceptable anti-interference ability, stability, and storage capacity. In order to evaluate the practical application value, the proposed microfluidic sensing device was applied for detecting eight archaeological samples from different historic sites. This work demonstrates great potential for high-throughput, portable detection of cultural relic proteinaceous binder materials.

Evolution of coalescent agent-free ultra-low VOC paint with formaldehyde capturing properties

The majority of people spend a significant portion of their waking lives indoors, they are continually exposed to a higher concentration of indoor air pollutants. As new technologies emerge and more people become aware of the issue, it has become crucial to discover new methods for cleaning up polluted indoor air and minimizing people's exposure to it.This research aims to develop a waterborne, low-VOC, formaldehyde-capturing formulation for interior paint. In paint formulation, biocides, coalescing agents, ammonia, binders, and liquid phase additives are all possible sources of volatile organic compounds. In this study, formulations of coalescing agent-free and formaldehyde-free waterborne coatings with high performance characteristics and ultra-low VOC content were created by chemically adsorbing formaldehyde using an active ingredient. The colorimetric method, which is developed based on the color concentration change, and the cabin method test methods, which monitor the change of formaldehyde concentration in the interior environment, were developed within the scope of the study in order to test the effect of the product. The final formulation complies with the A + French VOC labeling and the Indoor Air Comfort Gold criteria for VOC emissions, and tests demonstrated an 87% decrease in ambient formaldehyde concentrations within 24 h of application (ISO 16000–9:2006, EN 16516:2017).

On the way to tempera grassa: Unraveling the properties of emulsion-based paint binders

Painting technique in Europe underwent a major change in the 15th century, when the use of egg yolk as a binder in tempera painting was gradually replaced by oil paint. This transitional period probably saw the occasional use of a mixed technique called tempera grassa, in which both types of binders, egg and oil, are mixed in the form of an emulsion. In order to better understand and document this historical painting practice, this article describes the physico-chemical aspects of emulsion-based binders, prepared with egg yolk and either raw linseed oil, or linseed oil partially saponified with lead oxide. Highly stable direct emulsions can be prepared with linseed oil (raw or lead-treated) and egg yolk. Remarkably, lead-treated oil also allows the formation of stable inverse emulsions. The rheological properties of direct emulsions are driven by the oil fraction: as this parameter increases from 0 to 70 wt% oil, the emulsion changes from a viscous liquid to a viscoelastic solid, which allows its flow to be easily tuned by the painter. The impact of egg yolk on the drying mechanism of the emulsion is elucidated thanks to the combined use of NMR relaxometry and FTIR spectroscopy.

Can traditional artist's pigments hinder paint binder characterization using immunofluorescence microscopy? Application of widefield fluorescent and confocal laser scanning microscopies for advanced imaging and surface topography scans

Can traditional artist's pigments hinder paint binder characterization using immunofluorescence microscopy? Application of widefield fluorescent and confocal laser scanning microscopies for advanced imaging and surface topography scans

Characterization of Freeze-Thaw Treatments Upon Binders in Ancient Chinese Wall Paintings by X-Ray Diffraction (XRD) and Attenuated Total Reflection – Fourier Transform Infrared (ATR-FTIR) Spectroscopy

This study investigated the physico-chemical properties of the binders used in ancient Chinese wall paintings under repeated freeze–thaw cycles. Gum Arabic, cow bone, and fish bladder glue samples were prepared before and after three, six, and nine freeze–thaw cycles. The surface morphology, crystallinity, and spectral characteristics were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The secondary structures of the protein binders were also analyzed before and after thaw–freeze cycles. The results show that the surface morphologies of the gum Arabic, cow bone, and fish bladder glue gradually changed from undulating to smooth as the number of freeze–thaw cycles increased. The intensities of the XRD peaks and crystallinity of the binders gradually decreased after six freeze–thaw cycles. ATR-FTIR spectroscopy indicated that no significant changes occurred in the original chemical compositions of the binders after multiple freeze–thaw cycles. The wavenumbers of the characteristic peaks remained unchanged but the intensities of the peaks changed significantly. Analysis of the secondary protein structures indicated that the α-helix contents of the cow bone and fish bladder glue samples decreased significantly, whereas the parallel β-sheet and random coil contents increased.

The Wall Paintings in the Russian Church St. Nicholas in Sofia: a Technological Study by Integrated Analytical Approach

For the first time, wall paintings of 20th century Russian artists in Bulgaria were analysed by means of complementary analytical methods. Representative samples collected from the Russian church St. Nicholas in Sofia, decorated by the famous Russian artists Vasily Perminov, Michail Maletski and Nikolay Shelehov during different periods of time, were examined by means of micro-Raman spectroscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and X-Ray fluorescence (XRF). The results of the study reveal that colourful palette was achieved by using various pigment mixtures of traditional and modern synthetic pigment as titanium white, barium white, calcite, chrome green, green earth, hematite, ultramarine, madder lake, carbon black, vermilion, Naples yellow. The analysis of the paint binders allow to conclude that Maletski and Shelehov have used egg tempera as painting technique, while Perminov has worked in two painting techniques - oil and egg tempera.

Spectroscopic and mass spectrometry-based in-situ investigation of a 17th-century handwritten academic diploma on illuminated parchment

In 2008, more than 300 ancient scrolls, some of which were preciously illuminated, were recovered in Chicago (USA) after being stolen and illegally exported. These scrolls consisted of private and public documents, including papal and royal, dating from the 14th to the 19th century. The scrolls were returned to Italy and 42 of them, known as the Chicago Parchments, are now preserved at the State Archives of Bari (Italy). An illuminated academic diploma from the 17th century, known as doctoratus privilegium, was among them, and it was of particular interest to restorers and conservation scientists. To identify the pigments, painting binders, and animal skin origin of the parchment, non-invasive analyses were carried out on several points using portable X-ray fluorescence (XRF), µRaman, and fibre optic reflectance spectroscopy (FORS). Gold and silver decorations were confirmed by XRF, highlighting the significance of the document. A quasi-non-invasive sampling approach was used to analyze the painting binders by applying a trypsin-chymotrypsin enriched hydrogel for in situ digestion of the proteinaceous material. The extracted binders were successfully identified as bovine and rabbit glues by both matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry (MALDI-ToF-MS) and reversed-phase liquid chromatography with electrospray ionization tandem mass spectrometry (RPLC-ESI-MS/MS). By using bottom-up proteomics, the sheep skin origin of thin parchment samples was established from very small fragments that were digested in solution with trypsin.