Kathleen M. Garland and John Twilley
Egyptian limestone sculpture in Western collections has often been subjected to repeated, well-intentioned treatments that are the result of an incomplete understanding of the issues surrounding the removal of sculpture from an archeological setting to a poorly controlled interior environment. Remedial treatments often follow without scientifically investigating the causes of deterioration. An important Old Kingdom painted limestone relief from the tomb of Ka-aper (fig. 1) at The Nelson-Atkins Museum of Art will illustrate past treatment failures and successes, and the need for consultation and scientific investigation in planning re-treatments.
Severe flaking of the surface required consolidation to withstand de-installation from a wall in 1992, resulting in major staining. In 2006 experts gathered to study the deterioration and staining with re-treatment of the stone in mind. A scientific study included mineralogical analyses, pore size measurements and soluble salt content studies. Analyses of areas with staining or apparent prior consolidation revealed applications of natural resins, a drying oil, polyvinyl acetate and cellulose nitrate.
These results and the experiences of the consultants formed the basis for the re-treatment. Backing removal and desalination posed greater risks than surface treatment, while environmental control was seen as the means for preventing future damage. Consolidation was undertaken with methylcellulose paste. The stains from previous consolidation attempts were reduced using benzyl alcohol in Laponite poultices.