Identification of iron-gall inks with near-infrared Raman microspectroscopy

The identification of iron-gall inks on a number of 18th, 19th, and 20th century documents and a 12th century manuscript has been conducted using near-infrared Raman microspectroscopy. These historic iron-gall inks were found to display characteristic Raman bands generally occurring around 1475 cm(-1), between 1310 and 1350 cm(-1) (variable), 490-640 cm(-1) (combined broad band), and 400 cm(-1). These bands have promise as analytical spectroscopic markers for in situ non-destructive Raman identification of iron-gall ink on historic collections and were in good agreement with Raman data collected for laboratory-prepared iron-gall ink complexes and inks prepared following traditional iron-gall ink recipes. All historic ink spectra contained a fluorescent background, the degree of which varied between samples. Copyright (c) 2008 John Wiley & Sons, Ltd.