Developing Approaches for Conserving Painted Plasters in the Royal Tombs in the Valley of the Queens

The Theban Necropolis on the West Bank of Luxor, Egypt preserves one of the world’s richest repositories of ancient painted tombs, including those in the Valley of the Kings and the Valley of the Queens. Over three millennia, many tombs have been subjected to flooding, causing severe rock collapse and loss of surface decoration. How best to conserve and repair vulnerable wall painting in the tombs is an urgent issue.

Understanding the nature and composition of original materials is necessary in the selection of appropriate treatments for stabilizing fragile painted plasters. As a result, investigation of Egyptian plasters became a focus of study as part of the ongoing Queens Valley collaborative project between Egypt’s Supreme Council of Antiquities (SCA) and the Getty Conservation Institute (GCI). Based on a review of the literature, it was clear that the binder and aggregate composition of Egyptian plasters is not well understood. Despite a generally accepted belief that plasters were bound with gypsum and clay, past and current treatment approaches have relied primarily on lime-based repairs, poorly matched to the properties of original plasters. During recent episodes of flooding, the presence of such repairs has caused more harm to wall paintings, where differential stress reactions have led to cracking and loss in the weaker ancient plasters.

This study allowed for characterization, investigation and analysis of a wide range of New Kingdom period tomb plasters from the Valley of the Queens in order to clarify many unresolved issues concerning binder and aggregate types and ratios. Findings indicated that the ancient craftsmen had an empirically informed understanding of the properties and uses of gypsum and clay binders in mortars and plasters. In particular, the role of clay as a binder appears to be far more widespread and nuanced than previously recognized, and the stabilizing role of calcite in
plasters has been largely overlooked. These results have fundamental implications for improving the formulation of repair plasters for stabilizing wall paintings. The development of compatible repair plasters is therefore a key outcome of this project.