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.
Lee, A., Otieno-Alego, V., & Creagh, D. (2008). Identification of Iron-gall links with Near-Infrared Raman Microspectroscopy. Journal of Raman Spectroscopy, 39(8), 1079-1084. https://doi.org/10.1002/jrs.1989