For hundreds of years, cast iron tea kettles, known as "tetsubin," have been used in Japan and they are today 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 this even distribution of heat, the leaves gradually infuse the greatest amount of tea flavor into the water, offering you the greatest potential of flavor and nutrients from your tea. Additionally, a cast iron tea kettle keeps your tea warm for up to an hour and is more durable than clay or ceramic.

For your tetsubin to last, take the following steps before your first use:
– Rinse the cast iron thoroughly under hot water
– Dry the kettle with a cloth while it is still warm

Things to avoid:
– Do not wash it in a dishwawher
– Do not use detergents or abrasives on your kettle
– The inside of the kettle is glazed, so avoid using metal utensils inside it
– Avoid leaving tea or water in it for long periods of time
– While the kettle is warm, always wipe the outside with a dry cloth
– Do not cool the kettle suddenly while it is still warm
– Avoid salt or oil on and in the kettle
– Do not use in a microwave oven