Study of materials and techniques in painted ceiling panels from a palace in Cremona (Italy, 15th century)

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The exemplary case of a remarkably well-preserved historical musical instrument: the “Tuscan” Stradivari violin (1690)

In recent years, scientific diagnostic analysis has increasingly focused on historical musical instruments, especially bowed stringed ones. The materials composing the stratigraphy of these peculiar works of art are characterized by a complex and heterogeneous nature, which is representative of the working techniques employed by the great violin makers of the past. The entire coating system, so called wood finish [1], includes multiple varnish layers on a previously grounded wooden substrate to prevent varnish penetration. Over the time, however, the original stratigraphy of these centuries-old masterpieces could have been affected by the extended handling during performances and practice, the very close contact of the instrument with the musician skin, or, again, accidents and interventions of maintenance and restoration. As a consequence, variations in its coating thickness and composition have most often occurred. The object of the present study is one of the best-conserved instruments by Antonio Stradivari, namely the “Tuscan” violin (1690) today preserved at the Accademia of Santa Cecilia in Rome (Italy). Commissioned by the Medici family in 1684, as a part of the famous quintet, it is one of the earliest examples of the master’s multiple-layer varnishing method [2]. The remarkably well-preserved wood finish of the violin was non-invasively studied by UV-Induced Fluorescence (UVIFL) photography (by B. Brandmair), Fourier-Transform Infrared (FTIR) reflection spectroscopy and X-Ray Fluorescence (XRF) spectroscopy. The hypothesis drawn from the non-invasive approach was supported by a micro-destructive analysis performed on two micro-samples, one taken from the violin’s top plate (Fig. 1) and the other from the centre bass rib. The micro-samples were analysed by the Optical Microscope (OM) equipped with visible and ultraviolet lights and by the Scanning Electron Microscope (SEM) coupled with Energy Dispersive X-ray (EDX) spectrometer. The aim of the multi-analytical investigation was the characterization of varnishes, pigments and wood treatments constituting the violin’s stratigraphy, trying to understand the methods used by Antonio Stradivari to finish the instrument. From the results, the varnish is confirmed to be applied in a two-layer system: the uppermost salmon-fluorescent coloured varnish (Fig. 1, level A) is oil-resinous composed, with crystals of calcium oxalates witnessing the age of the varnish as a decomposition product of lipid materials [3]; the lowermost yellow-whitish fluorescent layer (Fig. 1, level B) is also characterized by an aged oil-resinous varnish with an aluminium- and oxygen-rich grain dispersed therein which gives rise to possible attributions, including that of alumina (Al2O3) as a substrate for lake pigments [4]. At the interface between the wood and the overlying varnish (Fig. 1, level C), probably related to a wood treatment, a proteinaceous compound can be likely identified as a binder of a few silica and silicates mineral phases. Moreover, rare particles of possible titanium-manganese-iron oxides and/or hydroxides as well as iron-containing aluminosilicates, both suggesting the possible presence of iron-based pigments such as red-ochre or umber earth [5], were found at this level. Under the treatment level, finally, small amounts of chlorine, sulphur, potassium and calcium could be ascribed to a wood pre-treatment method [2]. In conclusion, by combining data from the non-invasive and micro-destructive analytical campaign it was possible to propose a stratigraphic hypothesis of the “Tuscan” violin

“I Cantieri del Suono” project: a public-private cooperation for the valorization of the violin “Piccolo” by Lorenzo Storioni (1793)

The Cultural District of Violin Making is a network of Cremona municipality that keeps the search for quality violinmaking alive and constantly strives to defend traditional craftsmanship. It coordinates various groups in the city involved in education, teaching and research in the field of music and violinmaking. The Bracco Foundation, one of the leading arts patrons in Italy, has chosen to finance the “I Cantieri del Suono” project, dealing with this highly promising area. One of the projects aims consists in the acquisition and valorisation of a rare violin made by Lorenzo Storioni (Cremona, 1744-1816), involving all the main organisations in the District, plus the violin makers that work in the city of Cremona. This small-size violin, known as “Piccolo”, was probably made for a child. The instrument was played in the decades following its construction (1793), but then it has not been used for a significant period. It provides an extraordinary piece of evidence when it comes to construction techniques, the materials used and the composition of varnishes in late eighteenth century Cremona. The analytical protocol developed at the Laboratorio Arvedi di Diagnostica non Invasiva allowed collecting new data on the instrument through a non-invasive approach (XRF and FTIR spectroscopy, X-ray radiography, VIS-UVIFL photography, 3D laser scanning, OCT, NMR). The obtained results were discussed with the students of the Master’s degree in Conservation and Restoration of Cultural Heritage, aiming at identifying the best procedures to preserve the instrument and its materials. Meanwhile, the students of the International School of Violin Making took advantage from 3D model, making a playable copy of the instrument. The violin and its copy will soon enrich the Civic Collections and will be exhibited at the Museo del Violino in Cremona. Up to now different strategies of communications have been put in place (publication of a monography, social network notifications, congress for experts in the field). During the exhibition, attention will be given to the diagnostic results, accompanying visitors through different levels of technical insights

Discovering the coating structure of historic bowed string instruments: an analytical campaign by SR-FTIR microspectroscopy

In many cases, the possibility to analyze a micro sample from an ancient bowed string instrument allows researchers to collect a wealth of information concerning materials used by the great Masters of violin-making and their construction procedures. In fact, the stratigraphic investigation may provide important information about (i) the treatments of the wood, normally involving proteinaceous materials and inorganic fillers such as carbonates, silicates, sulphates, (ii) composition of the different superimposed layers of varnish, and (iii) organic or inorganic pigments dispersed in the binders of the different superimposed layers of varnish [1]. In the present work, a set of four micro-samples - collected from well-preserved violins made by Antonio Stradivari, Francesco Ruggeri and Lorenzo Storioni - have been mounted in cross section and investigated throughout. The analytical approach has been developed on the embedded samples by means of Synchrotron Radiation (SR) FTIR microspectroscopy in reflection mode using a 15X objective, at the Chemical and Life Sciences branch of SISSI beamline (Elettra - Sincrotrone Trieste) [2]. Data have been collected in the MIR range in correspondence of each single layer of the stratigraphy, setting the lateral resolution in order to match the layer thickness (from few microns to tens of microns). A classification model has been constructed and validated to discriminate classes of materials according to the spectral information [3]. Preliminary results obtained from measurements performed by the micro-invasive SR-FTIR approach are elaborated and discussed, together with the analytical procedures, in order to characterize the features of the different samples

Combining OCT and NMR-MOUSE techniques to study the stratigraphy of historical violins: the thickNESS project

In this work, Optical Coherence Tomography (OCT) and Nuclear Magnetic Resonance (NMR-MOUSE) have been applied to precious historical violins made by the most renowned makers of the Italian lutherie, such as Amati, Stradivari and Guarneri ‘del Gesù’, and hosted in the Museo del Violino in Cremona. Several large fragments removed during past restorations from instruments produced by the luthiers Stainer, Gasparo da Salò, Maggini and Guadagnini, as well as laboratory models simulating musical instruments stratigraphy, were further examined. OCT study was carried out with a prototype high-resolution portable SdOCT instrument providing layer thickness measurements and information about the presence of particles, cracks and delaminations. NMR analyses were performed with a Magritek Kea spectrometer and a Profile NMR-MOUSE (PM5) giving information on the wood density and elasticity, the last one possibly related to adopted treatments. The analyses have been conducted within the MOLAB Transnational Access - EU H2020 Project IPERION CH (thickNESS Project). Data interpretation is still in progress and promising results are expected to reveal in-depth insight into the finishing violin making process. These outcomes will be integrated with the results from UVIFL, FT-IR, Raman and XRF techniques in order to set up a methodology which allowed researchers to non-invasively characterize the stratigraphy of historical violins

From IR to X-rays: approaches to go through the coating system of historical bowed string musical instruments

Some historical bowed string musical instruments produced in Italy from the 16th to 18th Centuries are considered until now peak-quality masterpieces of the violin-making art. Technical skills were mostly lost after the disappearance of the prominent workshops, and nowadays ancient methods and materials are charming secrets to be revealed by scientific techniques. This work discusses the results obtained by investigating the complex coating systems on bowed string instruments produced by four violin-makers, namely: Jacobus Stainer, Gasparo da Salò, Giovanni Paolo Maggini and Lorenzo Guadagnini. They were selected in order to represent convincingly - albeit not exhaustively - the variety of situations that can be encountered when multi-layered coatings on historical bowed string instruments are considered. The coating systems have been investigated though micro-invasive and non-invasive procedures [1], employing UV-imaging, portable X-ray fluorescence, optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry and Fourier transform infrared microscopy. In addition, two tomographic techniques (synchrotron radiation micro-computed tomography and optical coherence tomography) have been used to image the finishing layers spread on the wood substrate [2,3]. Chemical investigations and images on cross-sections have been compared with the morphological view obtained by tomography, with particular attention to the ability of the tomographic insight to distinguish and measure the various overlying layers, and to highlight the presence of dispersed particles

Investigations through the coating system: the curious case of the historical bowed string instruments

The most outstanding violin-makers - among whom Antonio Stradivari is the most celebrated - were active during the 17th and 18th centuries, a period known as the “golden age” of violin-making. Since few documents have been left about methods of the ancient violin makers, most of their know-how have been lost through the centuries. Nowadays, ancient methods and materials are charming secrets to be revealed by scientific techniques. The present scientific investigation discusses the results obtained by investigating the complex coating systems on bowed string instruments produced by four violin-makers: Jacobus Stainer, Gasparo da Salò, Giovanni Paolo Maggini and Lorenzo Guadagnini. They were selected in order to represent convincingly - albeit not exhaustively - the variety of situations that can be encountered when multi-layered coatings on historical bowed string instruments are considered. The coating systems have been investigated though micro-invasive and non-invasive procedures [1], employing UV-imaging, portable X-ray fluorescence, optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry and Fourier transform infrared microscopy. In addition, two tomographic techniques (synchrotron radiation micro-computed tomography and optical coherence tomography) have been used to image the finishing layers spread on the wood substrate [2,3]. Chemical investigations and images on cross-sections have been compared with the morphological view obtained by tomography, with particular attention to the ability of the tomographic insight to distinguish and measure the various overlying layers, and to highlight the presence of dispersed particles

Mid and Near-Infrared Reflection Spectral Database of Natural Organic Materials in the Cultural Heritage Field

This study presents mid and near-infrared (7500-375 cm−1) total reflection mode spectra of several natural organic materials used in artworks as binding media, consolidants, adhesives, or protective coatings. A novel approach to describe and interpret reflectance bands as well as calculated absorbance after Kramers-Kronig transformation (KKT) is proposed. Transflection mode spectra have represented a valuable support both to study the distorted reflectance bands and to validate the applicability and usefulness of the KK correction. The aim of this paper is to make available to scientists and conservators a comprehensive infrared reflection spectral database, together with its detailed interpretation, as a tool for the noninvasive identification of proteins, lipids, polysaccharides, and resins by means of portable noncontact FTIR spectrometers

The case study of an Italian contemporary art object: Materials and state of conservation of the painting "Ragazzo seduto" by Remo Brindisi

This paper deals with the scientific survey of Remo Brindisi's painting “Ragazzo seduto” (Seated boy), made at the end of the 1950s, that is a symbolic figure of both his personal artistic solitude and the crisis of values determined by the economic boom in the post-war period. In a period of great changes and economic regrowth, the need to find a new style that could be the most authentic and personal as possible pressed the artist to experiment innovative products, including non-conventional support. Photographic and analytical techniques demonstrated the use of innovative products as an experimentation tendency, that pressed the artist to use non-conventional support, industrially treated with plasticized PVC and primed with acrylate polymers and to paint with traditional and industrial pigments mixed with an oil-modified alkyd resin. In the span of a few years, an unexpected and extended degradation on the whole surface of the painting took place, with the consequent formation of lifting and detachment of the paint film. The detected alteration is mainly due to the fast ageing of the employed polymeric materials, actually responsible of the impermanence of many contemporary works of arts. Clarifying the unknown aspects of the Remo Brindisi's stylistic choices together with the deterioration processes of the employed painting materials, this paper highlights the general problems related to the conservation of contemporary art, a neglected area of research in Italy, where more efforts are committed to the enormous and more ancient cultural heritag