cast iron kettle

Japanese Cast Iron kettles and teapots – the Story of the Water Energizing Tetsubin 

The cast iron kettle, or tetsubin in Japanese, is a hand crafted iron utensil, traditionally used in the Japanese tea ceremony for the heating of water. Of course, a kettle being used to heat water for tea isn't exactly newsworthy, but there is something pretty special about the tetsubin. 

The origin of the cast iron kettle in Japan is disputed, but it is thought that the tetsubin began gaining in popularity following the warring states period. After Tokugawa united Japan in 1603, weapon makers ceased their travelling and settled down. Looking for new markets, they began to satisfy the newly stable country's increasing demand for more domestically suited iron wares. The Tohoku region, abundant in iron resources, and ruled by a tea-enthusiast King called Nanbu, became the home of tetsubin. This holds true today, with Tohoku's Morioka, Mizusawa, and Yamagata prefectures still producing Japan's highest quality iron wares. 

Another theory holds that the Japanese cast iron kettle became popular with the introduction of sencha whole leaf tea from China, which was considered less formal, and was thus more widely consumed, than the powdered matcha. Regardless of its origins, the tetsubin rapidly became an essential part of the Japanese tea tradition, and several hundred years on, the cast iron kettle is a must-have for contemporary fans of Japanese tea culture. A large part of the tetsubin's appeal is the water enlivening properties of its cast iron material. 

A hand poured (and often exceedingly elegant looking) lump of high-carbon iron, this Japanese kettle imparts a distinctive flavour to the water boiled within. On a molecular level, the charge of the cast iron interior affects the viscosity of the water, and on a chemical level, the iron imparts a sweet mineral flavour to the water, which works particularly well with darker teas. 

Japanese brewing

We've touched upon the importance of water to a good brew before, and with a Japanese cast iron kettle, you certainly get tasty water. Whether you drink this water straight, or with your instant noodles is up to you, but we recommend it for enhancing the flavours a sweet, aromatic tea like Wuyi Black.

A real tetsubin is for life

The Japanese tea kettle is also celebrated for its longevity. When you buy a tetsubin, it's for life. It might  even be  an item to leave in your will for future generations to enjoy. That's because a tetsubin is essentially just a well-crafted lump of iron. For the same reason, it is also prone to rust. Medically, rust is completely harmless, but to avoid a build up of the red stuff, pour out any excess water after use and leave the lid off, so as to let excess moisture evaporate. 

If you do accidentally leave water in your tetsubin overnight, you can utilise the antioxidant power of tea: simply place some green tea leaves in the kettle, boil it for a while, and leave to stand for a few hours. If the rust really starts to bother you, you can scrub it gently with half a potato, but most experts strongly advise against using physical force to remove rust from the inside of your kettle. 

If rust appears on the outside of the tetsubin, you can heat the kettle, then rub it gently with a tea soaked cloth. To ensure the longevity of your tetsubin, it's also important not to add cold water to the hot tetsubin, or to heat the tetsubin when empty, as this will stress the metal. Tetsubin are traditionally heated over charcoal fires, but your gas or electric stove will work just as well. However, if you are using an induction heater, make sure to heat the kettle slowly, as the localised heat of an induction heater can also stress the iron (also check that your hot plate can stand up to the rough cast-iron of the tetsubin!). 

Japanese teapot

What do you call a Japanese teapot? 

That's the tetsubin covered, but how do you engage with centuries of Japanese culture while brewing the tea itself? The cast iron Japanese teapot, or tetsu kyusu, adopts the characteristic shape of the tetsubin, but is lined with enamel on the interior. This makes it suitable for combining tea and water in the typical fashion of the teapot, but means that you can't use it on the stove. 

The tetsu kyusu's enamel lining prevents rust, but it doesn't detract from the heat distributing and retaining properties of the cast iron. In an ideal world, you'd want both a Japanese cast iron tea kettle and teapot, but if you fancy a variation in materials, the Japanese are also responsible for a variety of exquisite clay teapots. If we've roused your curiosity in Japanese cast iron ware, then feel free to peruse our range of Japanese teapots and cast iron kettles. We stock a couple of charming tetsubin from Yamagata prefecture, along with cast iron teapots from Yamagata, and a few elegant pots made from Tokoname clay.