Factors Affecting Ancient Egyptian Wall Paintings

Coming from the past: lotus effect coatings for the conservation of ancient Egyptian wall paintings

Hussein H. Marey Mahmoud

Lecturer, Department of Conservation, Faculty of Archaeology, Cairo University, 12613 Giza, Egypt

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Abstract:

The tombs and temples of ancient Egypt are famous with their wall decorations. Different weathering factors are affecting the ancient wall paintings in Egypt. The main deterioration factors affecting these decorations are resulting mainly from the photochemical and physiochemical agents. In addition, the human factors play a significant role in the deterioration process. Visual observations of different wall paintings in Egypt have shown

An excellent example is an Egyptian blue sample from the tomb of Imhotep at the site of Sheikh Said (the 6th Dynasty). The glass phase is selectively decomposed and replaced by basic copper chloride, this phenomenon called ״Copper Chloride Cancer״. Egyptian monuments are known to contain considerable amounts of sodium chloride, when dissolved, it will also react with Cu (I) chloride in solution or copper oxide in the pigment to form paratacamite. Evaporation of water at the outer surface of the walls will lead to high concentration of sodium chloride (NaC1) in the residual liquid thus causing the precipitation of paratacamite on the outer surface of the pigment. This disease develops in stages; it starts with the diversification of the glass phase, followed by decomposition of the residual material. Migration of chlorine-bearing solutions leads to the reaction with copper in the residual glass. Copper and chlorine bearing solutions will then react with calcite and precipitate basic copper chloride to form atacamite. These solutions may migrate either inwards to the plaster layer thus filling the interstices between the gypsum or calcite crystals and replacing them, or to the surface of the pigment layer to deposit atacamite or paratacamite ( ). Fig. 1 shows different deterioration aspects on the wall decorations of the festival hall of Thutmosis III at Karnak temples complex, Upper