Non-destructive wood identification of historical Instruments based on 3D-reflected-light microscopy
In the history of musical-instrument making, traditional instrument builders consider it a fact that certain wood species used for different individual components of the instrument produce a defined sound which can be related to specific structures of the applied wood. In this context, one can assume that there is a great interest from contemporary instrument builders to know which species of wood the old masters like Torres or Stradivarius used.
The standard non-destructive method for wood identification is the macroscopic assessment of structural features. Regarding the results of a macroscopic identification, it should be evaluated as tentative; macroscopic observation (Figure 1) can refer only on a limited set of structural characters, as compared to the standard microscopic analysis (Figure 2). For identification of wood species in historical instruments, a microscopic examination is not possible due to the protection of the instruments, since no wood samples can be taken and prepared. In fact, in cases of closely related trade timbers, the use of macroscopic characters will finally end with a choice of several likely matches whose safe separation must be left to microscopic analysis. For “official” or “judicable” wood identification, microscopic analyses are routinely conducted. Using light microscopic techniques, up to 160 anatomical characters can be used which are internationally standardized according to the IAWA lists of “Microscopic Features for Hardwood and Softwood Identification”. The defined microscopic features describe the individual cell and tissue types: vessels, fibres, and parenchyma provide additional information about min-eral inclusions as part of a wood “anatomical fingerprint”. The use of digital 3D reflected light microscopy allows the microscopic investigation of flat and uneven surfaces of solid wooden components down to the smallest marquetry work without damaging the individual components.
This study aims at applying a state-of-the-art non-destructive identification method with a much higher resolution than offer standard microscopic image analysis systems.
In the frame of an STSM (COST Action FP1302), the authors analysed several classical instruments of the collection of the Museu de la Música de Barcelona.