pH Stability of Saffron Used in Verdigris as an Inhibitor in Persian Miniature Paintings
Saffron has been identified as having a significant preventive effect on corrosion caused by copper-based green verdigris pigments in Persian and Indian miniature paintings. A scientific examination of the chemical mechanism responsible for the buffering properties of saffron was carried out. The Saffron solution was found to be stronger than common buffers, i.e. more resistant to a wide range of pH in acidic and alkaline media. The chemical mechanism of this phenomenon, based on earlier research by the authors was sought. In addition, Persian medieval texts are discussed where the use of verdigris together with saffron is reported historically. The treatises used were mainly from the Safavid (16(th) century) and Qajar (19(th) century) periods.