The cooler is made of naturally cooling black-colored terracotta. When you need to keep our wine in perfect temperature just soak the cooler in cold water and fill it with water and ice. For red wine you'll only need water. Water evaporates through the walls of the cooler while cooling the bottle. This cooling process maintains the temperature longer than in a normal cooler. The bottom surface of the cooler has been glazed to protect your table from any excess water from the soaking process.