Analytical Challenges in the Study of New Kingdom Plasters from Tombs in the Valley of the Queens

A comprehensive study of Egyptian New Kingdom period (c. 1570-1070 BCE) decorated plasters was undertaken as part of a collaborative project between the Getty Conservation Institute (GCI) and Egypt’s Ministry of State for Antiquities (MSA) for the conservation of the tombs in the Valley of Queens. The study focused on identifying the material composition of historic plasters and understanding their current mechanical properties in order to develop compatible repair materials for stabilizing surviving areas of tomb paintings. The plasters that cover the walls and ceilings of tombs in the Valley of the Queens were found to be primarily earth-based, made from a readily available calcitic soil deposit at the foot of the Theban Mountains, known locally as hiba. This material, composed of calcite with clays (smectite, sepiolite and palygorskite), dolomite and/or ankerite, anhydrite, and quartz, could be used on its own mixed with water or with the addition of other materials such as clay, sand, plant fibers or gypsum to modify its properties. This paper describes the challenges in investigating these plasters: in particular, looking at analytical methods considered including microchemical tests, ESEM mapping, particle size analysis, and thin-sections. The goal of the paper is to highlight the problems that were encountered during testing and the difficulties found in the interpretation of data. Also discussed is the selection of specific analytical methods and the modification of existing techniques to better suit the particularities of the earthen materials that make up these plasters.