Near-Infrared Reflectance Spectroscopy and Authenticity of Performance: Indications in Bach's Music Manuscripts

Abstract

It is quite well known that supplementary entries were made in music manuscripts of Johann Sebastian Bach after his death in 1750. In most cases, however, the positive separation of later entries from original ones has remained an unsolved problem in Bach research. It is here demonstrated that reflectance spectroscopy in the wavelength range from 700 to 1200 nm can be used to detect and identify such amendments. As will be shown, irongall inks, commonly used in those days, often exhibit a characteristic optical behavior in the near-infrared region, which enables one to distinguish between entries made by different authors. In this particular study, performance indications in the oboe I part of Bach's cantata Wer da gläubet und getauft wird, BWV 37, could be traced to the hand of Carl Friedrich Zeiter, musical director of the Singakademie in Berlin (1800–1832), by comparing the reflectance spectra of the inks used for articulation markings (slurs) and ornaments (trills) with those of an undoubtedly authentic comment by Zeiter, found in the manuscript.