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Nanbu tekki: cast iron teapot or kettle, what is the difference?

Read it in Spanish!

Did you know that cast iron teapots are used to brew tea? Until not that long ago I always thought that cast iron teapots weren’t made to brew tea but just to heat water & therefore they were kettles. This was until I saw a comment in one of the tea groups I belong to & I decided to do some research. What I found left me perplexed & kind of confused too.


Yes, I also got confused myself. However, when doing the research about the topic I found an industrial designer who designs gorgeous cast iron teapots to be used to brew tea in the modern world. Surely there are many more outhere. There are cast iron teapots built with the only purpose of brewing tea & there are cast iron kettles which are used to heat up the water like the ones used in the tea ceremony. Before I continue, I want to say that you might see it written down as nambu instead nanbu (なんぶ 南部). It happens sometimes in Japanese language since there are different systems to be used when transliterating the Japanese characters into their romanized form. The Hepburn system is the most widespread one, especially outside Japan but it is not the only one. And there are two versions of it: Traditional & Modified. I learnt Japanese using the Modified system. For example, maccha, according to Japanese grammar this should be the correct way of transliterating the name of the powdered green tea. The reason, double sound duplicates first consonant of the next syllable (cha so c) then last syllable comes. It used to get me nuts seeing it written down as matcha yet it is the term that became popular & widely accepted so I ended accepting it too. The word nambu, is also interesting since the letter n is the only one together with vocals in the Japanese language that is used as a single letter. There is not such thing as m as a single letter but a syllable in this case would be mu. Namubu, but the name in Japanese is written as nanbu, this is because in Traditional Hepburn the syllabic n changes into m before the consonants b, m & p. After the off-topic geeky Japanese language mini-lesson, let’s continue talking about the Japanese cast iron teapot & kettle.



It literally translates into ironware/tekki (鉄器) from Nanbu (南部). It is produced in Iwate prefecture (岩手県,) Japan & its name comes from the feudal Nanbu clan which ruled the northeastern part of Honshu (本州)for over 700. The area was very iron rich & the iron making industry flourished in part thanks to the artisans that got invited to establish their workshops within the region in the 17th century. Overtime, the iron work from this area became a local specialty. It was expensive so not many could afford it yet it was really popular among feudal lords & the ruling classes.

The craft made it into modern times despite the World War II when many iron items were converted into weapons such as cannons & is still very expensive. The ironware artisans use traditional methods & techniques that take long time, effort & a high degree of skill. Handmade clay molds are used to make the iron wares & the name is geographically protected. Only the cast iron items made in the region of Iwate can be called Nanbu tekki.
There are around 70 companies that produce Nanbu tekki. They produce kettles, chimes, teapots & bowls. I have seen a nice pair of chopsticks rest shaped as a Nanbu kettle as well, they are in my list of things I want to get since they look super cute. There are other famous cast iron ware producing areas in Japan such as Yamagata. The cast iron ware produced in this region is called Yamagata imono.


For years, I have seen European cafés using cast iron teapots to serve Asian teas. This is thanks to a French tea merchant who visited Iwate in 1990 & suggested to create a wider variety of products for the European market. These type of cast iron teapots have enamel coating inside. According to what I read, the enamel coating is used for hygienic reasons, which makes sense since iron oxidizes easily. They cannot be used to boil water since the enamel coating would break when heated. This is one of the main differences between a cast iron teapot & an a cast iron kettle. But there are more. A good number of the cast iron teapots sold over the world are mass produced & made in China. They aren’t handmade & therefore we cannot know for certain which is the material that has been used in the manufacturing process. Often, they are coated with a layer of bright colour outside. I remember seeing some purple & bright pink ones in a mall when I lived in Germany.
The cast iron teapots are called tetsu kyuusu not to be confused with tetsubin (鉄瓶) which is the name for the cast iron kettle. I have one tetsu kyuusu that I got as a birthday present from one of my friends years ago. It is green outside, the interior is coated with enamel but the rim is not so it gets oxidized easily. I use baking soda to clean that part on regular basis. I never used it to brew any teas though. I don’t do teabags & I believe the water temperature is preserved for too long inside a cast iron teapot. I use it to cold down my tea brewing water since the iron absorbs the heat rather quickly though, then I move the water to my yuzamashi.
Said that, I brewed some black Japanese tea in it out of curiosity, just to analyze how the brew came out & how the material behaves. I roasted the tea leaves a bit before brewing them in the cast iron teapot. I used same parameters I use to brew in a kyuusu. The brew tastes nice (aftertaste) but I find it slightly flat actually. I will need to do a comparison by brewing the same tea using the same parameters but different teapots in order to grasp the subtle differences. So maybe, a future project for this blog.


A tetsubin is the Japanese cast iron kettle which has no enamel lining. It is usually handmade by high skilled artisans & used to boil water over a charcoal or electric heat source.
Since the tetsubin don’t have any lining they can get rusty really easily. They also need proper care & some prepping before you can begin to use them. And definitely they cannot handle sudden changes in temperature, from too hot to too cold in a split second, this might crack your kettle. If not made of 100% cast iron the kettle might also crack by being heated.
We used a traditional cast iron kettle during the tea ceremony classes. We had to heat it up after the ceremony until all the water evaporated & we had to allow it to cool down naturally. We scrubbed the bottom sometimes with pieces of newspaper in order to keep it clean.


Yes, there is more than one reason.
It is said that iron helps to improve the water for tea brewing among other things. In Asian countries like Japan or China especially they like to drink warm water since it is believed it promotes good health. This practice is called sayu (白汤) or shirayu in Japan & an iron kettle is used to boil the water. The water is to be drunk warm. This is a topic I would like to write about more in the future since there are a lot of things to say. If you have ever looked into the world of Japanese pickles (tsukemono/漬物) you surely have seen they sometimes use a piece of iron when they are pickling their vegetables.
Also, iron is a non-toxic material that has been used for centuries. It is also durable, it is not really easy to break a cast iron teapot unless placed on a stove which will make it crack. They look pretty & stylish, so when teas are served using these type of teapots they tend to look more authentic to end customers. Iron retains heat very well naturally, this is an ideal feature for cast iron kettles.
In some countries they use iron enriched water to prevent anemia. I found a study about this topic, you can have a look here. Since I am not a scientist, I will not recommend the use of cast iron teapots for health benefit reasons. It’s up to yourself as a consumer to read, get informed & make decisions.


It all depends on your needs & budget. Investing in a proper Nanbu kettle can be pricey. If you have a tea room & want to offer the whole experience, I would definitely recommend it. Or if you are tea ceremony practitioner & want to do it properly at home. You can always get a Nanbu teapot instead. I might invest in one of them in the future. But for now, I will keep using the one I got as a present since I don’t like to replace things unless I really need to. One of the disadvantages is their weight. They are not light, they are really heavy which makes it more difficult to lift them. Another thing to take into account is that if they fall on the ground, they will not break but they might break the tiles or the wooden slates. Or worse, the lid could fall on your toe & cause a concussion. I can be very clumsy sometimes, so I have to be extra careful when using my cast iron teapot. While there are no iron cast teapots or kettles in the shop at the moment if you are interested in getting one feel free to send me a message & I will see what my suppliers can do. Did you like the article? Hit the like button! If you haven’t subscribed to my blog, you can do so right now so you won’t miss any of my posts.

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