Each of our tetsubins has been enamelled on the inside and the quality of which conforms to various testing authorities specifications. As enamelled tetsubins they are known as 'kyusa' and are used for loose-leaf teas as well as herbal infusions and fresh herb teas. Each tetsubin teapot comes with a stainless mesh infuser to perfectly steep your loose leaf tea. Many tea enthusiasts claim the tea brewed in the cast iron Tetsubin teapot tastes better than tea brewed in any other teapot! Never use detergents to wash your cast iron teapots as this will have a negative effect on the taste of your tea, simply rinse with hot water. Enjoy!