Cast iron teapots are not usually listed with other traditional types of Japanese teapots. As a matter of fact, this is a variant of the so-called tetsubin (鉄瓶), a cast iron kettle that, unlike teapots, is used only to boil water (not to brew tea). Outside Japan, it’s difficult to find this kind of kettle while its variant, the cast iron teapot that outwardly looks like a tetsubin, is more common. This type of teapot is glazed with enamel on the inside to make it more practical for tea brewing. The Japanese call them tetsu kyūsu (鉄急須), or iron teapot, to make a distinction from the kettle. Cast iron teapots often come with a tea strainer that fits inside.
Cast iron teapots are very delicate and need great care as they get rusty very easily. It’s very important then to dry the teapot immediately after rinsing it with water (do not use any washing-up liquid). Other than that, it’s a very enjoyable utensil that has the advantage of keeping your tea warm longer than other kinds of teapots so it’s perfect for reading time.
My cast iron teapot is of a small size so it’s great when I’m on my own, reading a book, and I need my tea to stay warm long enough. It was purchased from Peter’s Tea House (the coloured versions are also very beautiful).