Alteration Processes and Deterioration Phenomena of Faience Tiles: Complex of King Djoser at Saqqara, Egypt

The Complex of King Djoser (2667-2648 BC) at Saqqara was the earliest stone building of its size in the world. Some of the walls of the substructure of the Step Pyramid and the so-called Southern Tomb were covered with panels of blue-green faience tiles. The present work aims to study causes of decay the faience tiles which coated Southern Tomb of Step Pyramid. Investigations and analytical techniques including scanning electron microscopy combined with energy-dispersive X-ray microanalysis (SEM/EDX), X-ray diffraction (XRD), X-ray florescence (XRF) and polarizing microscopy were used. Results show that body of faience tiles contains high ratio of silicon oxide SiO2 and low amounts of alkaline oxide (Na2O, MgO), copper was used to obtain the blue colour in an oxidizing atmosphere and fixing mortar of faience tiles consists mainly of calcite, quartz, gypsum, in addtion to halite. High content of moisture and crystallization of salts mainly halite salt were the main factors of faience tiles degradation.