Is Gold Yellow? Plant Dyes and Gold-Making in the Ancient Chemical Arts.

Ancient Greek colour terminology captures brightness, light, and brilliance rather than clear-cut portions of the chromatic spectrum, as scholars agree today. This also applies to the rich semantic of yellow, which we investigate starting from a philosophical and theoretical perspective. We then shift our focus to Graeco-Roman technical writings dealing with alchemical dyes, cosmetics, and other crafts that made use of the same set of ingredients and colouring substances. We compile a complete list of yellow-dyeing plants used in antiquity, which will update and enlarge the lists currently available in secondary literature on the topic, such as the seminal catalogue by Robert J. Forbes. Drawing on these data and on laboratory reconstructions, we address two main questions. First, which shades of yellow were usually associated with the colour of gold, and how were these tints produced by ancient craftsmen and alchemists? And second, how did these procedures contribute to the ancient discourse on the colour of gold and its artificial reproduction?