The Diversity of Newly Discovered Deterioration Patterns in Ancient Egyptian Pigments: Consequences to Entirely New Restoration Strategies and to the Egyptological Colour Symbolism

Polished cross sections through more than 1000 pigment samples from ancient Egyptian monuments (5th Dynasty to Roman Times) were investigated in reflected light, with SEM, and with electron microprobe techniques (EMPA). These combined analytical techniques allow many insights into the painting layers and down to the substrate. Textural relations of both the primary paintings and of the deterioration products can then be delineated. They also discern the stages of the various deterioration processes and the degree of damage of the painting layers. The textural patterns of six deterioration processes not known before are discussed in detail and are documented in BSE-micrographs. Five of these processes commence in synthetic Cu-pigments (Egyptian Blue, glass pigment, and Green Frit) and Fe-bearing glass pigments. The 6th process leads to the formation of complex phosphates and is mainly exogenous. It causes severe damage to natural and synthetic pigment layers. These processes result in destruction of the primary pigments and coloured decorations. Consequences as to the colour symbolism and future treatment of befallen paintings are discussed.