Tetsubin
鉄瓶/TET-soo-bin/
A traditional Japanese cast-iron kettle for heating water.
Also known as: iron kettle
A tetsubin is a Japanese cast-iron kettle used to heat water for tea, originally for sencha but adopted in modern matcha kitchens too. Cast iron retains heat steadily, releases trace iron into the water (some say it sweetens the brew), and looks like a small piece of furniture in any tea setup. For home matcha, an electric variable-temperature kettle is more practical — but a tetsubin makes the ritual feel more deliberate, and the iron contributes a small but real shift in water character.
In practice
- A cast-iron kettle used to heat water over a flame or brazier. The traditional ones are unlined inside, so the iron meets the water directly.
- Unlined iron leaches a small amount of dissolved iron into the water, which softens the mouthfeel — this is the reason people keep using them.
- Requires drying immediately after every use or it rusts. Empty it while still warm and let residual heat finish the job.
- Most 'tetsubin' sold in the West are enamel-lined teapots. These do not rust and do not season, but they also do not change the water — they are pouring vessels rather than kettles.
The common mistake
Putting an enamel-lined tetsubin on a hob. The lining cracks under direct heat. Only unlined cast iron goes over a flame.
