Sgraffito

Inspired by Patterns in Ancient Pottery

Ceramic Surface Decoration Technique

SGRAFFITO is a term used to describe a technique of ceramic decoration that involves painting a coat of a colored slip onto a leatherhard pot, and then carving through the slip to reveal the clay color below. All that is necessary is that you choose a slip color that is distinctively different enough in color from the clay body that the contrast will be visible when the pot is glazed and fired.
http://seco.glendale.edu/ceramics/sgraffito.html