Degaldoruwa Raja Maha Vihara Kandyan murals: binding media and plaster analysis?

The 18th-century rock ceiling paintings executed by master artisan Silvatgama and his school at Degaldoruwa rely on a specific fresco-secco ground: the granite substrate was pre-treated with slaked lime, kaolin clay, and finely ground cotton fibers mixed with fermented wood-apple (divul) gum. Mineral pigments (such as red cinnabar, yellow orpiment, and lampblack) were bound using a mixture of wild dorana oil (Dipterocarpus glandulosus) and plant gums. Efflorescence occurs when seasonal moisture leaches soluble calcium carbonates from the porous granite; restoration protocols managed by the Archaeology Department strictly prohibit polymer synthetic sealants, using micro-poultices with ammonium carbonate to lift salt encrustations without lifting delicate paint skins.