Near-Infrared Laser Scanning (NILS) to Differentiate Historical Inks, Deployed on a Stained and Faded Ninth-Century Fragment of Boethius Reused as Binding Material: Proving a Concept

Abstract

AbstractIn this paper we describe the use of a dual-wavelength near-infrared laser scanner (NILS) to reveal ink differences in a ninth century Boethius fragment. The scanning system worked at 680 and 780 nm excitation wavelength with a maximal resolution of 21 µm. Fresh images were recorded at both wavelengths and compared with others based on conventional methods, such as UV photography and infrared reflectography. Whereas the latter secured no new information for mapping and distinguishing via inks the layered genesis of the manuscript, images of the fragment based on infrared laser fluorescence revealed the different inks used to elaborate the manuscript. The method revealed and distinguished the respective inks used for glosses, other marginal notes, neumes and the main text. Furthermore, corrections and additions invisible under other types of light were discovered by NILS in combination with paleographic methods. The scope and limitations of NILS when used to investigate stained or faded reused parchment (Makulatur) and/or restored manuscripts are discussed in detail.