Identification of Green Pigment Used in Persian Wall Paintings (ad 1501-1736) Using PLM, FT-IR, SEM/EDX and GC-MS Techniques

The technique of oil painting was introduced to Iran via a cultural exchange with Europe in the Safavid period (ad 1501-1736). Since the first attempt at scientific conservation of wall paintings in Iran in the 1960s, the nature of green pigment used in Persian wall paintings has not been clear, although work on contemporary miniature paintings has identified malachite and verdigris. PLM, FT-IR, SEM/EDX, GC-MS and the study of contemporary historical treatises of the Safavid period were the main tools used in the present study to identify the green pigments in Persian (oil-based) wall paintings. Eight samples taken from the two famous Safavid buildings, Chehel Sotoon Palace and the Sukias House in Isfahan, were analysed. Here, the identification of copper-based pigment and of verdigris in oil as oleate amends the existing knowledge of the green pigment used in these paintings. It also suggests that oleate was introduced to Persian artists via the European influence on Persian painting as a result of cultural exchange in the Safavid period, when the technique of Persian painting changed from tempera to oil painting. However, as verdigris in oil and resin can appear as oleate over time, it is unknown whether the Persian artists did this deliberately or accidentally.