Willow Creek, Athens County Ohio is the source of this clay, where it is harvested and hand-processed to create this unique pottery. More than ten separate steps are involved in the crafting of each of these mugs. The interior and handle are glazed with food-safe glaze that shows blue to milky white depending on the temperature in the kiln. The unglazed exterior shows off the beautiful red of the clay and is safe for microwave and dishwasher. Look for "wc" on the bottom of each piece as a mark that it is Willow Creek clay.