Enamel is the fusion of powdered glass to metal, and artists like enameling because it allows them to add a painterly or illustrative quality to their work. Evidence of enameling goes back to ancient Greece. Throughout history, far-flung cultures favoured different techniques. For example, cloisonné enamel was popular during the Byzantine Empire, while artisans living in France and Germany in the Middle Ages preferred champlevé. And Art Nouveau jewelry designers favored plique à jour.