Tetsubin cleaning tutorial

DailyTX
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Wed Mar 09, 2022 3:12 pm

.m. wrote:
Tue Mar 08, 2022 3:03 pm
DailyTX wrote:
Tue Mar 08, 2022 2:18 pm
Update on the tetsubin lid. I was debating on using the traditional urushi method or the western method of restoring cast iron cookware. Due to lack of experience and materials here in the west, I decided to use the western method. The lid was heated up on a gas stove for about 30 minutes per side, and scrubbed with iron brush to clean off old urushi finish. The lid was rinsed in water to clean off the burnt particles, and then the whole lid was submerged in pure vinegar for about 2 hours. Fine steel wool was used to clean any uneven color surface, rinsed in water, and dried with a cloth. The outer side of the lid was oiled with grapeseed oil, and then heat it up again for oil to absorb into the iron. Not the best looking lid but it looks much better than the original photo :lol:
Image
I like the look of it very much. Well done! I think taking off the residues of the coating was a good idea. This way it can keep developing patina over time.
Thanks! This tetsubin is bigger than I expected, estimated 2-3 liters. I am thinking of using it as a camping kettle lol
akbarjan
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Sat Nov 26, 2022 5:13 am

To season your teapot, simply rinse it out with warm water and then dry it thoroughly. Next, rub a thin layer of cooking oil all over the inside and outside of the pot. You can use any type of cooking oil, but vegetable oil or olive oil work well.
Place the pot upside down on a baking sheet and then bake it in a preheated oven at 300 degrees Fahrenheit for about an hour. After an hour, turn off the oven and let the pot cool inside.

Once it’s cooled, rinse it out again with warm water and dry it thoroughly. Your teapot is now ready to use
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Victoria
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Sat Nov 26, 2022 3:43 pm

akbarjan wrote:
Sat Nov 26, 2022 5:13 am
To season your teapot, simply rinse it out with warm water and then dry it thoroughly. Next, rub a thin layer of cooking oil all over the inside and outside of the pot. You can use any type of cooking oil, but vegetable oil or olive oil work well.
Place the pot upside down on a baking sheet and then bake it in a preheated oven at 300 degrees Fahrenheit for about an hour. After an hour, turn off the oven and let the pot cool inside.

Once it’s cooled, rinse it out again with warm water and dry it thoroughly. Your teapot is now ready to use
Hmm, seasoning with oil makes sense for cast iron cooking kettles and pots, but for seasoning a water kettle for tea, I’d just stick with boiling tea leaves.
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Patjulian80
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Sun Jan 29, 2023 2:18 pm

Hi teaheads

I'm attaching the care instructions for my own tetsubin (not everything might be applicable to your make). It also confirms what Victoria has mentioned.

Hope this helps.

Cheers

Patrick
Tetsubin_care_instructions.pdf
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Victoria
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Sun Jan 29, 2023 3:13 pm

Patjulian80 wrote:
Sun Jan 29, 2023 2:18 pm
Hi teaheads

I'm attaching the care instructions for my own tetsubin (not everything might be applicable to your make). It also confirms what Victoria has mentioned.

Hope this helps.

Cheers

Patrick

Tetsubin_care_instructions.pdf
Thank you for posting this very good instructional @Patjulian80. Mind if I download pdf and share link in my original post?
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pedant
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Sun Jan 29, 2023 3:34 pm

thanks. OCR'd text:
Patjulian80 wrote:
Sun Jan 29, 2023 2:18 pm
Hi teaheads

I'm attaching the care instructions for my own tetsubin (not everything might be applicable to your make). It also confirms what Victoria has mentioned.

Hope this helps.

Cheers

Patrick

Tetsubin_care_instructions.pdf
About Iron kettle
1) High-temperature oxidation method (Uncoated finish)
In the traditional technique, the inside of the pot was baked at high temperature (about 800 °C/1472°F). The light gray film generated by the process plays two roles: "preventing rust inside the iron pot" and "eluting iron moderately".
* lf you scrape off the oxide film, it may cause rust, so be careful not to wash it strongly with a scrubbing brush or sponge.
•The original color of iron is silver, but once an oxide film is formed, it becomes light
gray.

1) Iron kettle cum teapot
A small iron kettle (with oxide film) that comes with a tea strainer.
It can be used not only for boiling water but also as a teapot.
Iron elutes inside.
• The inside of lron kettle or Iron kettle cum teapot is rough and light gray.

*The difference from Enamel teapot
Enamel teapot is coated with a glassy glaze inside and has a characteristic of being resistant to rust, but iron does not elute at all.
•The inside of Enamel teapot is glossy like glass and has a smooth black color.

2) How to use Iron kettle
1. First, lightly rinse the inside with water or lukewarm water (do not use detergent or
sponge). Next, boil water with the kettle and flush it 2-3 times.

2. lfyou add a full amount of water, it will boil over, so make it at most 70 to 80¾ and
heat the kettle over low to medium heat. To prevent water from boiling over, move the
lid slightly or remove it.

3. When water is boiled, put the lid back on the kettle, hold the handle and the lid with a
mittens or cloth, and pour slowly.

4. After each use, pour all the water until the very last drop and boil the kettle on a very
low heat without water. The water inside will evaporate in about 30 seconds to l
minute.

5. After the water evaporates, turn off the heat and let it cool. Gently wipe off any water
droplets on the iron kettle or the lid with a cloth.

3) How to remove the rust: "tea dyeing"
Using tea leaves, the tannin component contained in the tea leaves reacts with red rust to
tum black. lt is a method to prevent rust, and also recommended when the reddishbrown
color of rust is transferred to boiled water or metallic odor is felt too strong.
*You don't have to do it every day.
[ How to clean rust is also introduced in our You Tube video.]

*Put half or a cup of tea leaves such as sencha in a pack used for making Japanese
dashi, put it in an iron kettle with water, and heat it. Please adjust the amount of tea
leaves according to the size of the iron kettle and the spread of rust. The following is a
guideline for the amount of tea leaves.

-----
• Iron kettle or iron kettle cum teapot with a capacity of 0.3 to 0.7 liters
>a half cup of tea leaves
• Iron kettle or Iron kettle cum teapot with a capacity of 0.8 to 1.0 liters
>a cup of tea leaves
• Iron kettle or Iron kettle cum teapot with a capacity of 1.2 to 1.8 liters
>one and a half cup of tea leaves
-----

•When it boils, tum off the heat and leave it for about half a day (about JO hours).
•Drain the blackened water and tea leaves and lightly rinse the inside of the iron kettle.
•Finally, heat it on a very low heat without water to be dried.
By repeating this process 1 to 3 times, you can reduce the turbidity and metallic odor of
boiled water.

You can wipe off the rust on the back of the lid, the spout, and the handle by gently
pressing it with a cloth soaked in tea. The point is for tea tannins to permeate the rust.
Oolong or Pu'er tea leaves are recommended because they strongly dye rust black.
•Tea tannins can also stain, so be careful when using a light-colored cloth such as
white, pink, or pale blue.

Precautions for use
*The heated iron kettle becomes very hot, so use a mat to avoid damaging the table.
Please note that a cloth or wooden mat may be burnt or the color of rusi may transfer to
it.

• When you put the kettle on the fire without water for drying, please allow about 30
seconds to I minute. If you do ii for a long time, it will damage the kettle. Never take
your eyes o!T while the fire is on.

• Quenching a hot iron kettle can cause cracks. If you have heated the kettle for a long
time without water, be careful not to pour cold water into it (which will bum you with
steam) or place it on a wet cloth. Leave it as it is to cool down.

• To maintain the quality of iron kettle, basically only rinse it. Be careful not to rub the
inside or outside with a scrubbing brush or sponge. Also, do not use a detergent as its
odor will remain.

*Dishwashers and microwaves cannot be used for Iron kettle.

*Iron kettle cum teapot comes with a tea strainer. After using it as a teapot, do not leave
the tea leaves and hot water in it, but remove them completely. If they are left in, the
tannins contained in the tea leaves will continue 10 react with the iron. Thus, the taste of
the tea will gradually become bitter, or the color of the tea will turn black.

FAQ
Q1: Immediately after using it, rust appeared inside the iron kettle. Is it okay to use ii as
it is?
A: The inside of iron kettle always rusts. It is the proof that iron elutes, so please use it
with confidence. If you try to scrape off the rust forcibly, the oxide film applied inside
will be scraped off, so never do it.

Q2: Rust spread inside, and the hot water became reddish-brown and cloudy. It also
smells of metal. Is it okay to drink? What should I do to clean it?
A: A reddish-brown turbidity indicates an excess of iron. There is no harm in drinking
it, but if the boiled water or brewed tea doesn't taste good, try ©"tea dyeing".

Q3: The inside, the spout, and the back of the lid have become white. Should it be
washed off?
A: The white deposits are scale. Since they arc crystallized minerals contained in tap
water, they do not harm the body. Scale also prevents rust, so be careful not to scrape it
off. By regularly using mineral water (hard water) rich in minerals, scale will be quickly
formed.

Q4: The bottom inside the kettle now glows blue-green. Is it okay to use it?
A: Depending on the water quality of the area, it may react with iron to make the inside
glow blue-green, but there is no problem in use. Also, you may see something like a
thin oil film of seven colors on the surface of the water, but please be assured that it is
iron.

Q5: Does the color of the outside of the iron kettle fade during use?
A: Due to the heating of gas or IH, the color of the outside gradually changes from the
bottom. If you continue to use the kettle on high heat, the color will fade quickly, so it is
recommended to heat it slowly over low to medium heat. In addition, the color of the
handle, the spout, and the back of the lid, which are exposed to steam, will change and
also rust will generate there, but it is safe to use if you clean it regularly. Enjoy the
changes over time, which is called wabi-sabi in Japanese.

Q6: Is it okay to leave it on the stove?
A: Yes, it's fine. However, please be careful to keep water inside the kettle on low heat.
In some cases, the hot water evaporates while you take your eyes off the stove for a
while, and it has been boiled without water for a long time. Excessive heating without
water will damage the inside oxide film, bum the outer color, and accelerate aging.
Since a stove is difficult to adjust the heat, please use a little ingenuity such as placing it
away from the center of the fire.

Q7: Can it be used with an induction cooktop?
A: Yes, no problem. However, strong healing accelerates deterioration over time, so use
it over low to medium heat (The same applies when using with gas or stove).

Q8: When boiling water, black grounds are left on the bottom of the kettle. Arc these
pieces of iron? Is it okay to drink it?
A: They are the oxide film. In rare cases, the oxide film may peel off due to water
pressure when you start using the iron kettle. The film is light gray, but it becomes
black grounds when peeled off. Also, if you have done "tea dyeing" or brewed tea, the
fine powder of tea may dry out while adhering to the inside, and when boiling water, it
may come out as black powder. There is no harm in drinking the film or tea powder. It
will gradually disappear as you use the kettle.

Q9: Tell me how to store it when it will not be used for a long time.
A: First, boil the empty kettle until no water remains and let it cool as it is. Allow it to
cool c-ompletelyw, rap it in newspaper,a nd store it in a place where moistured oes not
collect easily. However, if it is left for many years, it may rust due to summer humidity,
so we recommend that you use it regularly.

Q10: When l opened the box, it smelled like ink. I can't get rid of the smell even if I boil
water. What should I do?
A: The ink-like odor is the odor of the outer paint. For a while after starting to use the
iron kettle, you may feel a strong odor when it is heated, but the odor will gradually
disappear by boiling water without a lid or continuing to use it Also, if you boil tea
leaves several times, the smell will disappear.

Q 11: ls there a way to tell if the iron ware I have is an iron kettle or a teapot?
A: If you want to tell whether it is an iron kettle, a teapot, or an iron kettle cum teapot,
check the inside of the main body. See"(!)High-temperature oxidation method
(Uncoated finish)"and "@Iron kettle cum teapot" for detail.

Q 12: When I was cooking, the oil flew into the iron kettle and it became a stain. How
can I get off it?
Since a stove is difficult to adjust the heat, please use a little ingenuity such as placing it
away from the center of the fire.
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Victoria
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Mon Jan 30, 2023 7:02 pm

Thanks for posting ocr’d text @pedant. I went ahead and added those links to my OP here.

Updates on this thread lead me to realize my tetsubin needed to be re-treated with tea leaves on the inside. I notice small flakes of rusted iron had fallen off from the inside of the uppermost underside of the pot. Happen to have a few days worth of spent black, oolong and green leaves (still fresh) so used those with filtered water. Once a slow simmer was established, I carefully spooned tea onto the hard to get to upper inside of the kettle and inside the spout that had some light rust going on. Brushed some tea onto outer surface of kettle as well since I was already at it. I let tea leaves and tea sit in the heated kettle (turned off heating element) for +-5 hours after which I simmered filtered water in the kettle two times. Just one 30 minute tea simmer is all it needed, all blackened again and water tastes good.

In a corkscrew fashion I spooned heated tea onto inside of inner-top of kettle, and ran tea through the spout many times.

greywolf
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Thu Jun 08, 2023 1:56 am

Hello everyone, I recently found this tetsubin at an antique store, and it is exactly what I've been searching for! Not sure of its age, but I'm thinking it's no more than 40 or 50 years old, based on condition. It seemed to be in decent shape, but there was some rust built up inside of it. It seems like that oxide layer has peeled off in some places, leaving rusty spots a few millimeters in diameter. So far I tried brushing the inside first with a brush made of natural material (like straw), just to get the big pieces off. Then I rinsed with water and boiled with some black tea. I let it sit for about 5 hours, drained and rinsed again. The rust was already turning black. So I boiled more black tea again and let it sit for around 15 hours. The tea that came out was even darker than before, almost black, and the rusty spots were more black than before. I boiled water once, and decided to do black tea once more. It is sitting and cooling off now.

I'm guessing it's normal to have a little bit of rust, as long as the water is clean and tastes ok. Is it dangerous to drink the water that comes out of the kettle if it is too rusty? Also, is it possible to send these type of kettles to a repairer to be reconditioned? Maybe someone can reheat them back up to 1000 degrees again and rebuild that "oxide layer" on the inside?

Anyway, here's some pictures. Any thoughts on its age or where it might have come from? I can't read Japanese kanji, but my fiance (who is fluent in Mandarin) figured out it is from the Morioka region of Iwate prefecture. I'm thinking it might be from Iwachu workshop.

Image

Image

Image

This one shows the remaining rust after two black tea treatments

Image

Can anyone read this?
DailyTX
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Thu Jun 08, 2023 7:49 pm

@greywolf your tetsubin is from the Kunzan workshop. I can’t read Japanese, but I have a tetsubin with similar mark. You can look at the tetsubin thread.
.m.
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Thu Jun 08, 2023 9:22 pm

@greywolf Nice score! It is in a great condition, barely used. Once you're done with the tea treatment, you can just start using it. There is always gonna be a little bit of rust inside, it is ok as long as it is under control. Not sure how much of iron can your body actually absorb this way, but it is good for you. Do not attempt to heat it empty, you'd burn off the urushi coating and plugs, possibly ruining it. ;)
greywolf
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Sun Jun 11, 2023 12:17 am

@DailyTXI think it might actually be from the Iwachu workshop. They have one identical to mine on their site, and after doing a bit of research, it turns out that is what the characters say on the outside of the kettle, but they are in an older formal way of writing (it's the lower character that appears to be outlined in a box)

@.m. Thanks for the advice! I did a third tea boil treatment, and that seemed to get it tip top, I'd say 95% of the rust turned black. I boiled fresh water in it a few times and I've been using the kettle daily ever since. It's working great!

If anyone's curious, I have a cheap dissolved solids test meter, so I ran a few water tests. First I used tap water, which registered at 33ppm, then after boiling the tap water in the kettle, it tested at 53ppm. Next I tried filtered water (I have a Zerowater filter) which showed 0ppm, boiled that filtered water and strangely enough, it only registered 1ppm after boiling in the kettle. I was expecting to see around 20ppm. Well, either way, it does seem to have a very mild effect on the flavour of the water, perhaps it is something that isn't detectable with the test meter I was using. Super happy with my purchase though!
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Baisao
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Sat Jul 01, 2023 5:43 pm

My understanding is that boiling tea leaves in a rusty tetsubin stains the existing rust and perpetuates the formation of Fe3O3 (red iron oxide, aka rust) by the exposure to tannic acid. The kettle would need to be treated with an alkaline solution like sodium bicarbonate to form blue Fe3O4.

Which oxide is preferable, I wonder?

Oddly enough, some carbon steel knives develop a protective blue-gray patina by cutting onions or smearing the blades with ketchup. Perhaps this patina isn’t an oxide but something’s else caused by sulfur in the onions (which is also an ingredient of ketchup, though acidic).
.m.
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Sat Jul 01, 2023 6:44 pm

@Baisao Good point. Things look to be more complicated than it has been reported here.
https://en.wikipedia.org/wiki/Tannic_acid wrote: Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue.
https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/tannic-acid-rusted-iron-artifacts.html wrote: When applied to iron, tannic acid reacts with the iron ions to form ferric tannate, a somewhat porous blue-black film whose degree of protection can be controlled to some extent by the method of application.
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Baisao
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Sat Jul 01, 2023 10:21 pm

.m. wrote:
Sat Jul 01, 2023 6:44 pm
Baisao Good point. Things look to be more complicated than it has been reported here.
https://en.wikipedia.org/wiki/Tannic_acid wrote: Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue.
https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/canadian-conservation-institute-notes/tannic-acid-rusted-iron-artifacts.html wrote: When applied to iron, tannic acid reacts with the iron ions to form ferric tannate, a somewhat porous blue-black film whose degree of protection can be controlled to some extent by the method of application.
That’s eye opening! Thanks
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