The first synthetic pigments were produced in antiquity. The methods used to create white lead, lead oxide, and verdigris did not change significantly until well into modern times. In the Middle Ages and the early modern era, innovations in color technology occurred mainly in connection with glass manufacture, smelting, and experiments by alchemists. Like the simple processes used to obtain white lead, verdigris, and lead oxide, these experiments were knowledge “in the public domain”. The knowledge was disseminated in artists’ recipe collections and in art books, though production was mainly in the hands of specialized craftsmen. By contrast, innovations in glass, ceramic and smelting technology tended to be handed down internally through apprentices and migrant craftsmen.