Crafted and hand-painted by local Japanese artisans, inspired by artworks painted by Kitagawa Utamaro. Each 'o-choko' (sake cup) Sakazuki is painted with a special non-toxic thermochromic pigment ink, and then coated with a food-grade clear ceramic glaze, to seal in the color changing ink.
Color Changing Feature: The color changes when the temperature of the hot color changing cup is above 103°F, and the color changes when the temperature of the cold color changing cup is below 70.5℉. The pigment is: temperature-sensitive materials are painted on the cup body and coated with a clear glaze, the materials used are heat-sensitive materials, high-temperature resistance of 608 °F, non-toxic, BPA-free, lead-free, chromium-free, and meets the FDA/EU standards.
Due to the delicate thermal reaction, there are cases where certain parts of the world are too hot or too cold that the cups arrive fully bloomed and activated out of the box. In this case, we recommend serving them at a different season or apply a heating or cooling method to reset the cups back to their original blank white with branches. Gentle hand wash is recommended to preserve the longevity of the cups and ink design, dishwasher is not recommended.