For hundreds of years, cast iron tea kettles, known as "tetsubin", were used in Japan and they are still a part of the Tea Ceremony in Japan. Why Use a Cast Iron Tea Kettle? Cast iron absorbs heat evenly allowing for the tea leaves floating in the water to evenly heat up. With the distribution of heat, the leaves gradually heat up infusing the greatest amount of tea flavor into the water. You get more flavor and the nutrients are infused water with the even heating. Your t