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 © 2008 John Wiley & Sons, Ltd.