Your First Tetsubin: How to Use It

Nurturing a tool.

Just as we follow the process of a living thing as it grows, there is a particular pleasure in watching the tools we use every day change and transform over time.

This time, we'd like to introduce the tetsubin (iron kettle), a piece whose weighty, substantial presence leaves a strong impression. "Raising" iron is a practice that can't be accomplished overnight—it's part of everyday life. Yet the character a tetsubin develops after five, ten years of loving use holds a charm found nowhere else, precisely because you are the one raising it.

Here, we introduce the care methods that will let you use a tetsubin with this long history for many years, and raise it into something uniquely your own.

Traditional Nambu Tekki (Nambu Ironware): Komaru

The tetsubin we carry at ZUTTO is the "Komaru" by Ogasawara Rikucho.

Its rounded, gently curved shape perfectly suits its name.

The Komaru was born in Mizusawa Ward, Oshu City, Iwate Prefecture. It is made at the Ogasawara Foundry, where caster Ogasawara Rikucho served as head.

In Morioka City and Mizusawa Ward in Iwate Prefecture, cast metalwork has flourished since the Edo period. Alongside the development of casting, the tea ceremony grew popular, and it is said that the tetsubin—a smaller version of a hot water kettle fitted with a handle—was devised during this time.

Afterward, the tetsubin spread throughout Japan as an easy-to-use everyday tool. While Ogasawara Rikucho continued the tradition of the classic Nambu tetsubin, he also introduced a simple, modern design, creating the "Komaru"—a tetsubin suited to contemporary life.

The Komaru is cast by pouring molten iron into a mold and then firing it. In the finishing process, it is baked at a high temperature, which forms an oxide film on the interior, giving it a structure that resists rust. This oxide film is arguably the tetsubin's most important

feature. The technique of baking at high temperatures is called "kanakedome," and it is said to have spread from Nambu tekki.

Because the oxide film protects the metal from corrosion, it becomes resistant to rust even when it comes into contact with water.

The Komaru is made entirely of iron, from the spout to the interior. Pick it up, and you'll feel just how solid and heavy iron truly is. This substantial weight gives it stability during use.

Another appeal is its sheer durability—it's said that in the past, tetsubin were the only items to survive a major fire with their shape intact. Just having one in your kitchen gives a reassuring sense of dependability.

Using a Tetsubin

Now, what points should you keep in mind when actually using a tetsubin?

Iron rusts when it comes into contact with moisture.

Naturally, tetsubin share this characteristic, so the most important thing is to keep rust to a minimum. In the case of a tetsubin, the oxide film created through kanakedome acts as a rust preventive, so maintaining this film is essential.

So how can you maintain this oxide film?

The key is to build up "yuaka" (mineral deposits such as calcium contained in water) before the film has a chance to fully wear away.

Once the yuaka has fully formed, the interior takes on a whitish appearance, and you can leave water sitting in the kettle overnight without it rusting, boiling water that tastes smooth and pleasant.

1. Rinse the inside of the tetsubin with water a few times.

2. Fill it with water and bring it to a boil over low heat.

Once it boils, discard the water.

3. Repeat step 2 several times, until the water inside is no longer cloudy.

4. Once the water runs clear, you can begin using the tetsubin as usual.

Use it to boil water for tea or cooking.

*After boiling water, don't leave it sitting inside the kettle—empty it right away. Leaving it in can cause rust to form inside.

1. Empty the hot water while the tetsubin is still as hot as possible.

2. Remove the lid and place the kettle somewhere well-ventilated.

The residual heat of the tetsubin will evaporate any moisture inside.

3. If the tetsubin doesn't retain much residual heat, place it over low heat. Heating it while empty puts strain on the kettle, so never use high heat—it can cause the surface at the bottom to flake off.

Also, once you've confirmed the tetsubin is dry, remove it from the heat immediately.

*Never touch the inside of the tetsubin with bare hands, a sponge, a scrub brush, or similar items.

When using a tetsubin, the important points are:

・Don't leave water sitting inside—dry it out right away

・Never touch the interior of the tetsubin

These two points are all you need to follow. Do so, and you can raise your tetsubin with confidence.

Rust on a Tetsubin

Earlier, we mentioned that the most important thing when using a tetsubin is to keep rust to a minimum.

That said, some rust on a tetsubin is unavoidable.

Perhaps a spot didn't fully dry after washing, or oil or water splashed onto it while cooking nearby.

These things happen.

Above all, a tetsubin naturally oxidizes from moisture in the air. So there's no need to feel discouraged if rust appears—simply accept that rust can occur for various reasons, and continue using it as you always have.

Even if red rust appears on the inside, it isn't a problem as long as the water you boil doesn't turn cloudy and red. Even if the rust bothers you, be sure never to touch the inside directly. If the water does turn red and cloudy, repeat the process of boiling and discarding the water. After doing this a few times, the water should become clear again.

If the cloudiness just won't go away, or if the water has a metallic smell, try boiling it with tea leaves added. When iron combines with the tannin found in tea, it has the effect of suppressing rust.

Boil for about 30 minutes, let it sit overnight, discard the water, and boil once more—this should produce clear water.

Please also rest assured that even if you happen to drink some rust, it is harmless to the body.

Yamagata Imono Kettle, Chushin Kobo Teapot

ZUTTO carries one more piece of imono (cast ironware).

It's the Teapot, Marutsutsu, S (Iron) from Chushin Kobo.

This piece represents Yamagata imono, a traditional Japanese craft that stands alongside Iwate's Nambu tekki (Nambu ironware). The history of Yamagata imono is said to date back as far as the Heian period.

Chushin Kobo, too, proposes cast ironware suited to today's lifestyles, aiming to pass on Japan's fine old traditional crafts to the next generation.

This teapot is one example of that effort.

The Teapot, Marutsutsu, S (Iron) is a size smaller than the Komaru, making it easy to place on a table. And the biggest difference from the Komaru is that the Teapot, Marutsutsu, S (Iron) is not a tetsubin (iron kettle) but a kyusu (teapot).

A kyusu is, first and foremost, a tea utensil used for brewing tea. Since tea leaves are placed inside and hot water is poured over them, a kyusu is never set directly over a flame.

Depending on the type of tea, water that has cooled slightly from a full boil is often said to be more suitable, so it also serves as a tool for letting the water cool down.

Another distinctive feature is that, unlike the Komaru, the inside of this kyusu is not left as bare iron but finished with enamel.

An enamel finish makes for easy, hassle-free care. If you look inside, both appear black, but can you tell that the Teapot, Marutsutsu, S (Iron) has a glossy sheen? Comparing the lids makes the difference immediately clear.

Because of the enamel finish, no iron leaches into the water poured into the Teapot, Marutsutsu, S (Iron).

This means you can't take in iron from it, but just like other tableware, you can wash the inside with a sponge. Both the Komaru and the Teapot, Marutsutsu, S (Iron) are imono, but their uses differ—one is a tetsubin, the other a kyusu.

・Made entirely of iron, including the inside

・Boiling water in it allows you to take in iron

・The effect of the iron gives the water a mellow taste

・Sturdy and resistant to breaking

・Will rust if not properly cared for

・The inside has an enamel finish

・You cannot take in iron even by boiling water in it

・Just like other tableware, the inside can be washed with detergent

Though their uses and characteristics differ, both have designs that feel right at home on the dining table. Despite being traditional tools of old, the Komaru by Ogasawara Rikucho and the Teapot, Marutsutsu, S (Iron) by Chushin Kobo have each been refined along with the times.

Rather than shying away from them, try using them. By enjoying how they change over time, they can become indispensable, treasured tools in your daily life.