Table 4 Raman band positions for Iberian inks and iron-polyphenol references; Raman bands used for a positive identification of iron-gall inks are shaded in blue, in historic documents, occurred around 1470 cm⁻¹, between 1315 and 1350 cm⁻¹, 490–640 cm⁻¹ (broad) and 400 cm⁻¹

From: New insights into iron-gall inks through the use of historically accurate reconstructions