Digital Maping of Egyptian Blue : Conservation Implications

Egyptian blue was extensively used throughout the areas surrounding the Mediterranean from early dynastic Egypt until after the Roman Empire ended. A new, easily applied, technique to detect and map this pigment has been developed that takes advantage of its very strong photo-induced infrared luminescence. Using this method, single particles of pigment can be detected, even when concealed by layers of discoloured organic binding media, varnishes or inorganic patinas. A survey of sculptures, friezes, mosaics and wall paintings from the ancient cultures of the Mediterranean and the Middle East has revealed expected and unexpected occurrences of Egyptian blue and rediscovered lost decorative patterns. This technique not only offers information on the manufacture, decoration and condition of the object, but also provides an opportunity to map the use of Egyptian blue both geographically and temporally. These new perspectives on ancient polychromy can help to inform future preservation strategies and conservation treatments that take this new information into account.