Non-invasive imaging and spectroscopy techniques for identifying historical pigments: a case study of Iranian manuscripts from the Qajar era

Abstract

In recent years, the expansion of non-invasive methods has been a trend in identifying historical pigments. Accordingly, this study aimed to identify the pigments used in three Iranian historical manuscripts from the Qajar era by utilizing a non-invasive and multi-analytical approach. A combination of various multi-band imaging methods, along with µ-XRF, Raman and FORS spectroscopy, were employed to identify pigments. The results revealed that emerald green, cochineal, ultramarine, orpiment, and red lead were used as pigments for green, red, blue, yellow, and orange colors on a golden leaf made of brass alloy. The study also demonstrated the mixtures of lead-barite white, lead white-ultramarine and lead white-red lead-indigo-cochineal in the white, light blue, and pink sections. While multi-band imaging was found to be a suitable tool for the primary classification of pigments, relying solely on this method without a complete pigment database is not advisable, as differences in underlying paint layers and mixed pigments can affect imaging results. Overall, the combination of imaging and spectroscopic techniques provides a reliable and non-invasive approach to identifying historical pigments and their alterations.