Spectroscopic Analysis to Characterize Finishing Treatments of Ancient Bowed String Instruments

Abstract

Historical bowed string instruments exhibit acoustic features and aesthetic appeal that are still considered inimitable. These characteristics seem to be in large part determined by the materials used in the ground and varnishing treatments after the assembly of the instrument. These finishing processes were kept secret by the violinmakers and the traditional methods were handed down orally from master craftsmen to apprentices. Today, the methods of the past can represent a secret to be revealed through scientific investigations. The "Cremonese" methods used in the 17th and 18th centuries were lost as the last Great Masters from the Amati, Guarneri, and Stradivari families passed away. In this study, we had the chance of combining noninvasive and microinvasive techniques on six fragments of historical musical instruments. The fragments were detached from different instruments during extraordinary maintenance and restoration treatments, which involved the substitution of severely damaged structural parts like top plates, back plates, or ribs. Therefore, the fragments can offer to the scientists a valuable overview on the materials and techniques used by the violinmakers. The results obtained by portable X-ray fluorescence, optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry, and Fourier transform infrared microscopy allowed us to: (1) determine the stratigraphy of six instruments; (2) obtain new information about the materials involved in the finishing processes employed in Cremona; and (3) elucidate the technological relationship among the procedures adopted in the violin making workshops during the considered period.

Approaches for Detecting Madder Lake in Multi-Layered Coating Systems of Historical Bowed String Instruments

“…It is known that, even in the past, the selection of colouring materials has represented a very peculiar characteristic of each workshop [3] and therefore the characterization of the colourants is of paramount relevance for a proper identification of the artwork, sometimes reflecting the crucial influence on the commercial value.…”

A Micro-Tomographic Insight into the Coating Systems of Historical Bowed String Instruments

“…During the last decade, scientists have proposed analytical protocols and procedures dedicated to the identification and characterization of the materials. The musical instruments were tested both through the most common non-invasive spectroscopic techniques [4][5][6][7][8][9], such as X-ray fluorescence (XRF), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) in ATR and reflection mode, and by micro-invasive analyses, such as micro-FTIR and scanning electron microscopy coupled with energy dispersive x-ray analysis (SEM-EDX) [10][11][12][13][14]. These works allowed scientists to highlight the diversity of the materials used by the ancient violin makers.…”

“…The presence of a multi-layered coating system frequently composed of a very thin proteinaceous preparation, applied directly on the wooden substrate, and an oil-resinous varnish has been detected in several musical instruments manufactured both in Brescia and Cremona. Moreover, some inorganic materials, such as sulfates, carbonates, and silicates [4,8,12,[15][16][17], as well as dispersed colorants [6,13,[18][19][20][21][22], were identified. The characterization of this wide variety of organic and inorganic materials-combined together in order to seal the wood porosity, protect the instrument from moisture and biological agents, and enhance its aesthetic appearance-represents the most challenging task in the investigation of the finishing layers in historic musical instruments.…”

The elemental composition of Stradivari's musical instruments: new results through non‐invasive EDXRF analysis

“…Inorganic pigments, probably red ochres containing iron (Fe) and manganese (Mn), were found in low concentrations, although the hypothesis that they might be contaminants was not ruled out. Organic pigments like red anthraquinonoid on an alumina substrate were also detected . Moreover, the presence of Pb, although in low concentrations, suggests the existence of litharge (PbO) or other compounds containing Pb used as pigments and/or catalysts to accelerate the oil drying .…”

“…Organic pigments like red anthraquinonoid on an alumina substrate were also detected. [15,16] Moreover, the presence of Pb, although in low concentrations, suggests the existence of litharge (PbO) or other compounds containing Pb used as pigments and/or catalysts to accelerate the oil drying. [11,17,18] In a few cases, the presence of cinnabar (HgS) was also reported.…”