Investigation of painted stucco in historic buildings of Delta, Egypt

Samples removed from stucco ornaments of two mosques (seventeenth century) in El-Mahalla El-Kubra, Delta, Egypt, are investigated using optical microscopy, micro-Raman and micro-FTIR spectroscopy and X-ray diffraction (XRD). Samples are studied as removed from the ornaments and after treatment with trichloromethane, which was used to extract the organic content. Moreover, the stratigraphies of the ornaments are investigated through a sample’s cross-section analysis revealing a bulk stucco layer, a colouring layer (either red or black) and overpainted layers of later interventions. Red and black colouring layers are composed mainly of fired brick enriched with hematite and carbon black, respectively. Shellac, found in high quantities, is the binding medium used in the colouring layers where small amounts of tree resins are detected as well. Bulk stucco is composed of gypsum and calcite. Metal soaps, oil and tree resins are also detected in the stucco layers. Other identifications are described in the report which, to the best of our knowledge, is the first effort to identify the materials contained in the “Delta style” stucco used in Ottoman buildings in Egypt.