Bluer than blue: Defining Pliny’s Egyptian blues

An ancient Roman wall painting with a blue sky tells little of the range of colorant choices from which a Roman artist potentially could have chosen. Gradients of Egyptian blue were available in a good commercial market. This range is made clear by two sources, Pliny the Elder’s Natural History (late 1^st c. A.D.) and Diocletian’s Maximum Edict of Prices (301 A.D.), both of which indicated that there more than one kind of Egyptian blue existed, each at a different price point. This study seeks to define the four Egyptian blues discussed by Pliny, exploring in particular what feature(s) might have differentiated the most expensive variety, known as Vestorian blue, from the other Egyptian blues. A tripartite study will be undertaken to explore the differences in Roman Egyptian blues. First, there will be a careful exploration of Pliny the Elder’s text. Then, the scientific analysis of archaeological examples of raw Egyptian blue will be surveyed in order to explore what variables in manufacturing techniques or ingredients could set these blues apart. Finally, the information gleaned from the literary and archaeochemical study will then be tested by manufacturing modern examples of Egyptian blue. These manufactured samples will be evaluated for their suitability for painting and measured archaeometrically in order to understand their properties. Such a study will make it possible to better understand the knowledge of materials that Egyptian blue artisans had in mind when making materials.