By Jessica R. Hallett, Michael Thompson, Edward J. Keall and Robert B. Mason
Canadian Journal of Chemistry, Vol.66:2 (1988)
Abstract: Microscopic examination and electron microprobe analysis were employed to determine the materials and techniques used to decorate ten glazed types of medieval Islamic ceramics from North Yemen. Eight types were underglaze-painted, one was slip-painted, and one was monochrome glazed. The glazes were of two compositions, soda–silica and lead oxide – silica with annealing temperatures of approximately 835 and 640 °C, respectively. The colourants used in the glazes and paints were cobalt (blue), iron (green), copper (green and blue), and antimony (yellow). Where clay slips or slip-paints were present, alumina enrichment of the glaze had occurred during application or firing, and pigment-paints on top of slip grounds masked enrichment. The Mellor ratio for the lead glazes ranges from 0.68 to 0.74 and is well above the acceptable safety limit of 0.5.
Introduction: The Yemen Archaeological Project is concerned with the history and culture of a medieval Islamic university town, Zabid, and its interaction with neighboring settlements and the outside world, from A.D. 700 to 1750. Zabid is 25 km inland, half-way between the Red Sea and the Yemeni highlands, on the Tihamah coastal plain. In the absence of any previous systematic archaeological work in the region, the initial surface reconnaissance involved collection of pot sherds from abandoned sites in order to establish a ceramic typology, as a way of determining the nature, location, and period of settlements in the region. Sherds (2400) were collected and classified from a total of 73 sites within the 100 by 70 km study area. Almost all of the pottery is considered to be of local manufacture, and can be divided into separate types according to the colour of the fired clay, shape, and surface decoration treatment. The pottery can be tentatively dated by association with import pieces from other countries, such as 15th century “Ming” blue-and-white porcelain or 13th century Yuan celadons.