FoMRHI Comm 2003 Marco TiellaA triangular spinet of unknown Italian maker (second part)The article describes the results of a series of physical investigations on the remains of old metal strings for keyboard instruments.1 A) Old metal strings possibly drawn in NurnbergFourteen reels of wire were found in a cardboard box together with the small triangular spinet2 whose details were published in the Comm.1983.The little wooden reels, all of the same weight (2 loth – 1 loth =1/30-1/32 of a pound) have four different designs imprinted on them (see the following table) and were numbered by the same hand (presumably that of the wire producer or dealer) that also wrote n6 on the reel (picture published by Domoulin).3 Wires of different gauges 1 The values published here are to be regarded as average evaluations. Denzil Wraight checked string samples very precisely by measuring the diameters in different directions. DENZIL WRAIGHT “Principles and Practice in Stringing Italian Keyboard Instruments”, Early Keyboard Journal 18 (2000), 175-238.2 At the time, many questions arose regarding the opportunity of getting wires with physical characteristics like those of the original old strings , having checked that the use of spring steel wire was completely inappropriate for getting any “old” tone colour, as was generally done for pre-war reconstructed keyboard instruments. Word was going around that in the Nürnberg Germanishes National Museum, wire strings, specially produced in Sweden for imitating the “old” tone colour, were being used. In fact, the remaining pieces of old strings showed that the iron alloys were lacking in carbon proving that the kind of wire drawn for the thin diameters required (as little as 0.15 mm) was at that time not yet on the market.It is unknown from where the firm Zuckermann got the wire that was sold with their harpsichord kits.To get strings of truly old iron, at the IROR (Istituto per la Ricerca Organologica e il Restauro, Milano, 1990) strings were made from shanks of nails pulled out of a wooden structure dating back to the end of 18th century. So, iron strings as thin as .20 mm were readily made by hand (the thinnest diameter obtained in the process of drawing before the breaking point at 120÷140 Kg/mmq, following the procedures depicted in RÉMY GUG “Histoire d’une corde de clavecin …”, musique ancienne 15 (1983), fig. XVI, p.18.3 PIERRE DUMOULIN, “La decouverte des bobines des cordes de clavicins du XVIIIe siecle”, Revue de Musicologie, Tome LXI – 1975 N°1, p. 115, planche A, where four different reels are shown. From the resemblance between the shape of reel N°6 in the picture (with the impression of an eagle) and the imprinted design of those preserved in the cardboard box (with the impressions of the initials HMF with a rose and a flamingo), it is now possible to suppose that all the reels might have had a common commercial origin in Nuremberg. Indeed RÉMY GUG (“En remontant la filière de Thoiry à Nuremberg”, musique ancienne 18 (1984), p. 30) quotes J.CH. SCHEDEL’s statement (Neues …Warenlexikon, Wien, 1811, p.398) that “the wires for musical instruments made in Nuremberg on reels … [are] marked with a deer, the Imperial Pommel or the globe”. The last two imprinted

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were wound around the reels.Designs imprinted on the reels:

a) Imprinted designs on the reels found together with the spinet:”Bell” (n.12), “II Flamingo” (n.9), “Imperial pommel” (n.11?) and “HMF rose” (n.6)

designs correspond exactly with the ones within the spinet cardboard box.

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b) Imprinted designs on two of the reels published by Dumoulin:”Winged lion”and “Eagle” (n.6).

Iron (I) or brass (B) wire drawing chart:Draw number Diameter Amount of wire on reel4 B 37/100 full or nearly full 5 B 33/100 full or nearly full6 I 33/100 nearly full7 I 28/100 nearly full7? I 25/100 small8 I 25/100 nearly full8 I empty8 I empty8 I empty9 I empty9 I empty11? B 17/100 empty12 I 16/100 nearly full12 I empty12 emptyPieces of the wire strings were still present on the instrument when

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the spinet was acquired. It is impossible to ascertain how it was originally strung due to the fact that the instrument seems to have been shoddily modified at some stage so that the keyboard lost its original shape as well as the correct order of the keys.From the confused pieces of strings found on the spinet, it is not possible to reconstruct any tone succession but the series of reels, even if not complete, allows us to assume that it is what remains of the actual string assortment.Amount of wire on the reels:full or nearly full: 4 (brass), 5 (brass), 6, 7, 8 , 12 (brass)empty 8, 8, 8 , 9 , 9 , 11 , 12 empty, 12 empty.Seeing that the number 8 reels are the most numerous, it is reasonable to assume that the spinet was basically strung with wires of 0,25 mm thickness, in accordance with what is usually thought to be normal for plucked keyboard scalings. It is more uncommon to find remains of wire thinner than 0,20 mm (0,17 and 0,16) on old instruments. The presence of brass wire of 17/100 mm is rare and we suppose that this gauge was produced for musical purposes also.Metallurgical investigationsUp to the moment when I acquired the reels of wire and started my research, the most detailed investigation into seventeenth-century metal string production was to be found in the articles by Remy Gug, where there appeared a picture of reels similar to the four above-named.Data not obtained before, has since been provided thanks to the intervention of several scientific institutions.

Collation of metallurgical specifications of strings of different origin

(1981) Work done by prof. G. Wolf and L. Calliari4 4 G. WOLF - L. CALLIARI, Università di Trento and IRST, Trento, “Caratterizzazioni meccaniche e chimiche di spezzoni di corde per strumenti musicali”, published in Comune di Milano, Atti del seminario per la didattica del restauro liutaio, Premeno (Novara) 1982, pp. 37-80.

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The micro-hardness was tested on at least 6 points of the string cross section using the Vickers method1) Samples of iron strings - Tensile strength.Material Abbreviation Max and min diameter Surface condition Piece of old iron string N° 8 0,24÷0,23 corrodedPiece of “Zuckermann” iron string 0,225÷0,24 corrodedPiece of “GNM”(5) iron string 0,24÷0,24 fair Hardness Standard deviation

Estimate stressPiece of old iron string 356 kg/mmq 22 120 Kg/mmqiece of “Zuckermann” 431 Kg/mmq 25 145 Kg/mmqPiece of “GNM” iron string 386 Kg/mmq 22 130 Kg/mmqThe “Zuckermann” sample was found to have the maximum micro-hardness dispersion value.2) Samples of brass strings - Tensile strength.Material Abbreviation Max and min Diameter Surface conditionOld brass string N° 5 0,315÷0,34 goodOld brass string (17th C.) 0,21÷0,22, good “Ormiston” brass string 0,25÷0,26 good Hardness Standard deviation

Estimate stressOld brass string N° 5 232 Kg/mmq 15 78 Kg/mmqOld brass string (17th C.) 248 Kg/mmq 18 83 Kg/mmq “Ormiston” brass string 254 Kg/mmq 28 85 Kg/mmqThe “Ormiston” sample was found to have the maximum micro-hardness dispersion value.- Chemical characteristics.

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In order to accurately identify the chemical composition of a wire’s external layers, a spectroscopical analysis with Auger electrons was carried out. Thus, any chemical substances were able to be detected through the examination of their energy spectrum. When the sputtering technique was combined with the Auger spectroscopy, the bombardment by Argon ions was able to wear away the external layers so as to arrive at the internal core of the sample. Therefore, by drawing up a profile of the consecutive layers, it was possible to reconstruct the history of the samples. 1) iron and steel wiresThe surface of the original iron wire had obviously been corroded by environmental pollution, so large amounts of carbon, oxygen and chlorine were detected, whereas traces of tin were present in the modern “Zuckermann” and “GNM” samples. It has to be presumed that the presence of tin is due to the wire drawing process. Moreover, the tin was also present in the deeper layers of the “Zuckermann” sample. Carbon and oxygen were still present at the depth of ca 0.5 mm where an interesting peculiarity appears; namely, the presence of a peak of aluminium. As this phenomenon could not be accounted for, further investigation is needed.2) brass wiresThe spectra and profiles of the three types of wire were similar. At the first sputtering, carbon, oxygen, chlorine and sulphur peaks were present but thereafter the most evident element became copper. The quantity of zinc varied between 27% and 30 % in both the original and modern alloys.Some remarksBrass wiresDifferences in the chemical composition and physical properties regarding the three samples of brass strings did not turn out to be evident but analyses on the re-crystallization phenomena of the string materials, which had been under stress for many years, were at a level near the maximum that they could withstand.Iron wiresThe coating of ferrous oxide covering the badly corroded original N° 8

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string would presumably change its acoustic response. Therefore, replacements with suitable modern wires should not give a tone quality presumably near to the original one.

Profiles of three iron samples “MHF”(1), “Zuckermann”(2), “GMN”(3)Brass wires

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Profiles of three brass samples (1) “Ormiston”, (2) “HMF Rose” 5 and (3) Brass String found on the Spinettino

(1981) Work done by Prof. Gianni Podda5 The tests were done with an Instrom material testing instrument, although the machine attachments used to hold the samples proved to be not firm enough. For this reason it was impossible to determine the elasticity modulus of the wires.A sample of an Ormiston brass wire was tested to draw parallels with the other iron wires.Material Abbreviation Diameter Breaking stress Breaking tensionAncient wire N° 8 A 0.225 mm3.18 Kg 80 Kg/mmq“GNM” wire S 0.235 mm4.9 Kg 13 Kg/mmq5 Prof. GIANNI PODDA – Politecnico di Torino, published in the Comune di Milano, Atti del seminario per la didattica del restauro liutaio, Premeno (Novara) 1982, pp. 32-36

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“Zuckermann” wire K 0.225 mm5,9 Kg 48 Kg/mmqOrmiston” brass wire O 0.225 mm4,6 Kg 0 Kg/mmqStress/elongation diagrams are shown.

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Figures from 1 to 5 show which stressing cycle each diagram refers to

B ) Other investigative techniques which were applied:- Spectroscopy ICP-MS (Inductively Coupled Plasma Mass Spectrometry)A highly sensitive technique which can detect a range of metal at concentrations below one part per trillion by linking together an inductively coupled plasma as a method of producing ions with a mass spectrometer as a mean of separating and detecting the ions. Thus the presence of various metals (impurities) in the wire can be ascertained.(1991)Work done by Dr. Giovanni Intelisano, Dr. Vanes Poluzzi, Dr.

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Massimo Baldi6 The results obtained from testing a number of strings found on ancient keyboard instruments are listed:1) Reels in the box with brass wire HMF N° 4 – Fe 1% Zn 70% Cu 37%HMF N° 5 – Fe 0,3% Zn 72% Cu 14%HMF N° 10 – Fe 1% Zn 74% Cu 25%2) Reels in the box with iron wire HMF N° 7 – Fe >95% Zn tracesHMF N° 8 – Fe >95%HMF N° 9 – Fe >95% Zn tracesHMF N° 12 – Fe >95%

6 GIOVANNI INTELISANO, Dr. VANES POLUZZI & Dr. MASSIMO BALDI, Presidio Multizonale di Prevenzione USL31, Ferrara, “Analisi delle corde mediate spettroscopia ICP-MS”, published in MARCO TIELLA & ROMANO VETTORI, Strumenti per Mozart, Rovereto, Longo Ed. 1991, pp. 357-360.

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Fig. 1 – Scansion of the so-called “white” (the comparison sample)Fig. 2, 3, 4, 5 – Scansions of the iron wire samples HMF 7 and Pianoforte N° 12 at different scales.

Examples were selected from 43 tests of various strings7 as:3) Reels in a box found in an antique shop (Turin - Italy)N°0, N°1/0 ½ , N°2/0, N°3/0 ½ , N°4, N°4 ½Fe >95% nd traces of Zn in all the samples4) Other pieces of strings found elsewhere:7 MARCO TIELLA & ROMANO VETTORI, Strumenti per Mozart, Rovereto, Longo Ed. 1991, pp. 359.

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a) on a harpsichord modified into a fortepiano (Sicily, 17th-18th C. shown in Comm. 1915, 2010)brass string : Fe 3% Zn 61% Cu 42%iron strings : Fe >95%, traces of Zn in a single sampleb) on a fortepiano constructed by Luigi Rasori (Bologna, Italy, first half of 19th C.)brass string : Fe 5% Zn 72% Cu 31%c) on a fortepiano constructed by F.lli Sander (Turin, Italy, end of 18th C.)iron string : Fe >95%in all the samplesd) on a fortepiano constructed by an unknown maker (Austria, first half of 19th C.)iron string : Fe >95%in all the samplesf) on a fortepiano constructed by Streicher (Austria, 1820).iron string : Fe >95%; traces of Ag in a single sample- Microanalysis by SEM (Scanning Electron Microscope)(1991) Work done by Dr A. Aleotti and Prof. F. Zucchi8

The samples were prepared according to the procedure for metallographical tests, by incorporating the sample within a slide of acrylic resin and then corroding the wire section with NITAL. The samples were previously covered with an Edwards 4 carbon film. The tests were carried out by a Cambridge Stereoscam 360 at 20 KV and 70 nA.Traces of Ca, Al, Mg came evident on the wires by using nitric acid diluted in water. Due to the presence of chemical elements traces in the comparison sample in concentrations near to those of the impurities detected in the string alloys, it would be incorrect to assign reliable values to the elements Pb, Ni, Al, Ar, Ba, Cu and Zn, if present. So, the results clearly show that it is the presence of traces of Zn, Ag in the iron samples (Fe) and Fe in the brass (Sn, Cu) samples which have enlarged the spectra graphs. In fact, other chemical substances (ArN, 8 A. ALEOTTI, Centro di Microscopia Elettronica, & Prof. F. ZUCCHI, Dipartimento di chimica, Università di Ferrara, “Osservazione e microanalisi al microscopio elettronico a scansione SEM”I, published in MARCO TIELLA & ROMANO VETTORI, Strumenti per Mozart, Rovereto, Longo Ed. 1991, pp. 369-373

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Cr. ArO, ArOH) had interfered with the Fe isotopes.In contrast, in the brass wire samples the Fe peak does not prevail over Cu and Sn peaks, thus remaining a mere impurity.- Microanalysis by EDAX (Energy Dispersive X-ray Analysis)This method detects the X-rays produced as the result of the electron beam interaction with the sample under SEM (Scanning Electron Microscope)

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Fig. 1 - Micography of a cross section of the string HNF 4 at 200 enlargements.

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Fig. 1 A - Scansion microanalysis of the string HNF 4 by retrodiffused electrons.Fig. 1 A bis - Scansion microanalysis of an impurity in the string HNF 4.a) Brass stringsResults : A number of linear flaws are visible on the brass string of fig.B. They have been enlarged (fig. A) and an extraneous substance highlighted (fig. A bis). As elements not pertaining to the alloy Cu/Zn were not made evident, the extraneous substance was probably produced by oxidation. A Zn phase rich of Zn, presumably of “beta” phase, was found in negligible quantity.

Fig. B – “Sander n. 3” iron string - Microscopy scansion by secondary electrons (on the left); Microscopy scansion by retrodiffused electrons (on the right)b) Iron stringsResults : Extraneous substances were not found in iron strings, except for flaws visible on the iron string “Torino 4 ½ “possibly of earth substances (fig. C).

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Fig. C – “Torino 4 ½” iron string - Microscopy scansion by retrodiffused electrons (on the left); Microanalysis (on the right)- HardnessMicrohardness values (HV) tested by “Vickers” Miniload Leitz gave the following result for the iron string samples:HMF 4 HV 297“Turin” 4 ½ HV 311“Sander” N°23 HV 306Interesting to note the uncommon structural flaw found in a sample of an ancient iron string by C. Canevari, IROR, Milano, 1981.

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