Cast iron kettle guide (history, benefits, tips, care, and FAQs).

Antique Japanese cast iron kettle

If you have or if you’re looking at purchasing a cast-iron kettle, then you probably have a few questions such as how can I use my kettle? Or my kettle has white spots. These questions are important, after all, you want to look after and take care of your kettle, so it lasts a long time. In this article, you can learn the history of Japanese kettles and how to use them. But also you can learn the following:

  1. What is a tetsubin?
  2. How artisan’s make tetsubin
  3. Important considerations if you want to buy a tetsubin online
  4. Learn the benefits of using cast iron kettles
  5. How to use your kettle correctly
  6. Important care instructions with easy to follow dos and don’ts
  7. Frequently asked questions
Guide to using cast-iron kettles

History of Japanese cast iron kettles

Japanese cast iron tea kettles are to boil water. The Japanese have used cast iron vessels for hundreds of years to boil water for the household and to humidify their homes. Today the kettle or tetsubin is as popular as ever, and if you buy one for yourself, it will likely to have the same traditional designs used hundreds of years ago.

Tetsubins originated in the early 17th century and were traditionally hand-crafted by Japanese artisans who utilized two traditional crafts that the Japanese are widely known for, pottery and metalworking.

The results are quite often stunning combining: simplicity, functionality, durability, and beauty.

Today the Japanese still make some of the best kettles, and many artisans make them using traditional methods. Ironware from Iwate is particularly famed and is called either Nambu Tekki or Nanbu Tekki, depending on the translation.

Artisans tools to make bespoke hand-made kettles
Iwachu cast-iron workers workbench. Most of Iwachu manufacture products on a large scale. But they still make individual cast-iron kettles.

What is a cast iron tea kettle? 

An authentic cast iron tea kettle does not have an enamel lining. Many kettles sold in the West often have an enameled finish on the inside but are sold as tetsubins. These are cast iron teapots — not kettles. They are known as Tetsu Kyusu in Japan. Enameled teapots are for steeping tea and not to boil water. You cannot use them to heat water on the stovetop. 

For more information about the differences between cast iron teapots and cast iron kettles, check out this article. 

Kettles come in a wide variety of sizes and colors. Many feature intricate designs on the outside like dragonflies or cherry blossoms. Try to avoid mass-produced cast iron tea kettles if you can. However, traditional Japanese tetsubins are not cheap. There are cheaper raw iron kettles on the market, but traditional Japanese kettles command premium prices.

How do artisans make cast iron kettles? 

High-quality tetsubins are labor-intensive to make, which is why they are often expensive. It can take 60 or more steps to make one tetsubin. In Iwate, local artisans have to train for years to make these vessels. Iwachu Casting Works has been making kettles since the early 1900s. Here is a simplified process on how an Iwachu Tetsubin is made:  

  • First, artisans make two clay molds, one for the body the other for the spout
  • Then, workers pour raw iron into a clay mold 
  • Workers break the mold to release the kettle while still red hot
  • Rough edges are rounded, and checked for imperfections
  • Finally, artisans apply a lacquer on the outside to protect the kettle from rust

Did you notice the first two steps use a clay mold? A clay mold is a traditional method to make cast iron kettles in Japan. Today only bespoke kettles are made this way, and they can be expensive. However, most ironworks now manufacture cast-iron kettles using sand molds. A sand molded kettles are significantly cheaper than a handcrafted kettle.

Cast iron kettle in clay mold
The light is terrible but the picture is a great example of how a cast-iron kettle is made. You can see the kettle is in a clay mold that was hand-made and is smash open after firing.

How are Tetsubins different from a regular tea kettle? 

Cast iron tea kettles are great for enhancing your tea drinking experience. That is because the high iron content of the tea kettle helps remineralize the water making it softer.

This means that tea brewed with water from a tetsubin is sweeter and more mellow than tea brewed in another fashion. Because of this, some tea connoisseurs like to brew water for tea with a good old fashioned kettle.  

Other considerations when purchasing a cast iron kettle

An authentic Japanese tetsubin traditionally has a special oxidized coating. This happens when the kettle is heated over charcoal fire until glowing hot. The charcoal firing slightly changes the atomic structure of the iron from standard Fe⁺3 into Fe⁺2. This oxidized layer helps prevent rust and adds to the taste of the water.

Benefits of cast iron tea kettles 

Besides the unique way of brewing tea, cast iron tea kettles offer many benefits. Here are just a few of them. 

  • Non-toxic. Cast iron has been used in cookware for thousands of years and is non-toxic. You don’t have to worry about drinking toxic chemicals along with your tea when you heat water in a tetsubin.
  • Durable. Cast iron is virtually indestructible. With the proper care, a cast iron tea kettle could last forever. 
  • Versatile. Tetsubins are versatile. You can use them for a variety of tasks: Brew iron-rich water for your morning oatmeal. Cast iron tea kettles are also pretty display items for the kitchen.
  • Retains heat very well. Iron naturally retains heat. This means that your water will stay warm and will cool slowly. 

Good for your health. By brewing your water in a tetsubin, you can add a little extra iron to your diet. Researchers know that cooking in cast iron adds iron to the food. The same goes for brewing water in a cast iron tea kettle. I also have an article called is cast iron safe? If you want to learn more.

How To Use A Cast Iron Tea Kettle 

Traditionally, tetsubins were used over a charcoal fire. However, you can heat your kettle over direct heat or on the stove. Just make sure your tea kettle is 100 percent cast iron before using it on the stove. Otherwise, it may crack or warp. You can use a tea kettle on either an electric or gas stovetop. They can also be used on some glass burners. However, read the instructions to be safe.

Before using your cast iron tea kettle for the first time,

  • Wash the inside out with cold water
  • Then, boil water in the kettle over medium heat until the water becomes clear
  • You may have to repeat this process several times before using the water  
  • Now the kettle is ready to use, fill it three-quarters full of water and place it on your heat source
  • Use low to medium heat
  • After the water starts boiling, slide the lid aside to let out the steam. This will keep boiling water from dripping out of the spout, which will reduce the risk of burns.
  • Then simply pour the water over your tea leaves or steep your tea in a teapot. If you want to know how to use a cast teapot check out this article.

Tip: Heat you kettle on low to medium heat. I recommend a low to medium heat not only for cast-iron kettles but also for cast-iron cookware. This is because modern cookers heat very quickly, and cast iron is softer than modern cookware, so iron moves and expands when exposed to rapid temperature changes.

Important Use And Care Tips 

  • Do not touch any part of the tea kettle with your bare hands as it will be very hot. Always use an oven mitt 
  • After transferring the boiling water to your teapot, make sure you replace the lid on the kettle
  • Do not pour very cold water into an empty cast iron tea kettle that you have pre-heated. This could cause it to break
  • Do not leave standing water in your kettle. This is a surefire way to cause it to rust 
  • Avoid contact with oils and salt
  • When cleaning your tea kettle, do not use harsh soaps, detergents, or scrubbers. Simply wipe the outside with a clean, dry cloth. Then, turn the pot upside down to air dry
  • Store your cast iron tea kettle in a cool, dry place. Make sure you completely dry it off first
  • Use a trivet when your kettle is hot to avoid damaging your table and kitchen bench. Also, use the trivet to display your kettle as the high iron content can discolor surfaces

Frequently Asked Questions (FAQs)  

What Are The Red Spots Inside My Cast Iron Tea Kettle? 

These red spots are natural phenomena caused by the high iron content. They are no cause for concern. 

Why Are There White Spots On The Inside Of My Tea Kettle?

You might notice white spots on the inside of your cast iron tea kettle. These spots are normal and are minerals which are concentrated from evaporated water. These minerals form a layer on the kettle and will help prevent rust. 

How Do I Remove Rust From a Cast Iron Tea Kettle?

You can still use a cast-iron tea kettle that has rust. However, if you’d like to remove the rust, simply fill the kettle with tea leaves and boil the water. The tannic acid in the tea will help remove the rust and form a natural barrier helping to prevent a future recurrence. 

Can I Microwave My Cast Iron Tea Kettle? 

No! Cast iron tea kettles are not made for microwave use. They are suitable only for use on a stovetop or over an open fire. 

Can I Put A Cast Iron Tea Kettle In A Dishwasher?

A cast-iron tea kettle should not be put in a dishwasher. If you must clean a cast iron tea kettle, wash the inside with mild soapy water. Then, wipe out the kettle and place it upside down to dry completely. However, many will say you should never clean a kettle or teapot.

How Do I Keep My Cast Iron Tea Kettle Looking New

To polish the surface of the tea kettle, simply wipe it with a soft cloth soaked in tea. This will help keep it glossy. Also, keep your kettle away from the stovetop. So there are fewer chances of oils coming into contact with the kettle.

How much do cast iron tea kettles cost? 

Tetsubins or cast iron tea kettles usually cost a bit more than cast iron teapots. They run anywhere from less than $100, but hand made versions usually start at several hundred dollars for even small versions. I recommend the Iwachu Japanese iron Tetsubin Tea kettle.

Although it costs a bit more than other tea kettles, it is well worth the investment. And could very well be the last kettle that you will have to buy. Iwachu has a good reputation for making high-quality cast iron products. 

cast iron kettles on display
Iwachu tetsubins for sale in Morioka, Japan. Note: behind the kettles is information on who made which kettle.

A cast iron kettle is a great addition to any serious tea-brewing collection. These durable vessels can be handed down from generation to generation. Cast-iron kettles have many uses aside from just brewing water for tea. They also make pretty decorative items to display in your kitchen and are often a focal point with guests.

References:

  1. Holy Mountain Trading Company (Japanese cast iron Tetsubin)
  2. Go ask Alice (Does cooking with cast iron pots and pans add iron to our food?)
  3. National Center for Biotechnology Information (Dietary Iron by Fady Moustarah; Shamim S. Mohiuddin)
  4. Artistic Nippon (How to care for your rusty cast iron kettle)

2 COMMENTS

  1. This is very helpful, thank you! I am getting my husband a cast iron tea pot for our 6th anniversary gift. He loves having tea throughout the day and also has low iron, so I think this will be the perfect gift!

    • Hi Alana

      Thanks for your kind message, I’m so pleased you found the article useful.

      Congratulations on your anniversary. I hope you both have a very special day.

      I think a cast iron teapot is a great idea. If a teapot has an enamel inner there will be little to no iron added to the water. But it would be easy to clean. However, some cast iron teapots are seasoned on the inside instead of enamel which adds a little iron to the water. Both are a great choices and I’m sure your husband will be over the moon to receive such a thoughtful gift that will last many years.

      Cheers Alana

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