Tuesday, March 12, 2013

Heating water on charcoal- part two: Stoves and Kettles

Promised for ages, here it is: The post about stoves and kettles for boiling water for our tea. Since The Part one I was using and testing different stoves with different kettles. We were trying new clays, shapes and glazes and we had some succesful combinations as well as failures. The first part of this story was focused on charcoal itself and on how to use it. But as I have few new findnings about things which I have already spoken of there, I will start with those.

So some quick notes first:

- Even if you are not washing your charcoal, make sure it is dry enough. I find out that even opened bag of charcoal may absorb some air moisture. The charcoal will work but with much more smoke and smell, especially during lighting. So, if you would like to have smokeless time - dry your charcoal and keep it closed in dry place.

- If you are making tea outside, the heating water will, most likely, take more time. Especially cold, windy day (which can call for nice outdoor tea session) can be tricky. Moving air is cooling the stove, kettle and moves the heat all directions. It may seems to be marginal but lets try it and you will see. The putting the stove on sheltered place and using more of well lighted coal can fix that.

- Another combination which can slow your heating down is too big kettle or with wide bottom on small stove. Some stoves work with wide range of kettles, from big tetsubins to small glass boilling teapots. But usually there is certain size of the kettle which works best. Shortly: If you close the top of the stove with the kettle, there will be no draft and the fire will be inefficiant.

 There are many stoves or heaters around the world. I have experinces mainly with our own and I am going to talk about those. Our stoves are, basically, of two kinds. I call them "with the sieve grate" and the second one "with the flat grate" Those with sieves are Mirka's original invention and I am glad to admid that those works, in most cases, better. On other hand the stand or flat grate system allows shapes, which are not easy to make with sieve. To understand more, please take a look at picutres.

In first case there is kind of sieve, which works both as grate and as a place where the kettle sits. Great thing about this kind of stoves is that you can use charcoal of almost all sizes and shapes. You can put there big pieces (as far as they can fit there) as well as fragments from the bottom of your bag. Just if you are using your stove for more then one and half hour, still feeding it with new charcoal, you will need to clean holes in the sieve. I use old chopstick and it works just fine.

The flat grate is made as a stand and sit on the bottom of the stove. Or there is just grate which sit, thanks to shape of the stove, on walls of the stove. I like this style, but the burning of the charcoal is more tricky. You have to have rather bigger pieces of the charcoal and you need pay more attention how you set it up. Those simly needs more care.

To make sieves and grates more thermal shock resistant, Mirka mixes her own mixture of clay, silica, grog and sawdust. The main body of the stoves are usually made of clays manufactured for cooking. When you go through my pictures you can see several clays, with few glazes or slips which works for low temperature. We actually fire our stoves to two different temperatures. To thermal shock safe, but more fragile 850°C and to 1250°C in woodkiln. Those from 1250°C are much harder, but it is more risky for cracking with charcoal fire. So far, it did not happen with the clay we use now.


With kettles, there are many choices out there. And thruth is that for quality of your tea water is the kettle even more important then the stove. Your kettle can be made from silver, stainless steel, iron testsubin, ceramic, glass. Every material will impact the water its own way. All can be in different qualities, sizes, designes and, of course, price ranges. My experiences are limited to few testsubins, glass and many (mostly my own) ceramic kettles.

Glass is hard, clear, cold - they say that it leaves water how it is. Glass boiling teapots are pretty cheap and practical. I like to watch boiling water in glass with live fire under it. I think, it is good starting point, when you learn how to work with charcoal and stove. When there is not much going on it terms of improoving water it does not make it poorer either (as some stainless electric kettles do).

Iron kettles - Tetsubins, are incredible things. I am not an expert on those so just few words here. Good tetsubin ad to water some iron and makes water more live. If you had a chance to drink tea made with water from good iron cast teapot you know. Unfortunately there are many inferior as well as really bad ones. Even good testubin can get rusty and you will get more iron then you may like. I have very nice testsubin (spoussedly fifty years old), which isquite rusty inside. I dont use it on daily basies, which could help to clean it. The water taste nice, but for most teas is too irony. People ask me just for the water and nobody wants to drink tea.

Especially if your water is poor for minerals then good tetsubin can make you happy. But as good tetsubin is real  investment, in both money and what we expect from it, dont buy it in rush. Make sure you know what are you looking for, make some research first. One of MarchalN's posts can be helpful too.

Ceramic kettles are, as you can expect, my love. Again, there are many kinds and origins out there. When we put aside the size and dezigne what counts is material and firing. If your kettle is glazed, then it is closer to glass teapot. Unglazed clay impact water and the lower firing tempretaure usually means more porous clay and the stronger impact. I saw Jappanese teapots (boffura), which were fired so low that that water leaks through and whole body was covered by small drops of water. The water taste from lime (calcite) and clay. If your tea water is too soft (poor in calcium, Ca(HCO3)2) then it can be what you need. You can find kettles, which go from this porouse, underfired clay to hard and waterproof stoneware. For now, I use manufactured clay, which is sold for cooking ware. It works when we fire it around 1230°C and most teapots do not leak. The clay makes water more rounded, with nice mouthfeel. It is clean and live.

With ceramic kettles or boiling teapots, there is always issue of cracking over the fire and thermal shocks. For our kettles we give some qurantie, all kettles are tested, but basic rules have to be kept.

-our quranties aplly, when our kettles are used on charcoal fire, not gas or electric. Some of them will works even on gas or electric burners and for very long time (I use mine) But, if I had some of them cracked then it was on electric and ges fire - never on charcoal. .

-don't put empty or almost empty kettle on the fire

-never pour cold water in to hot, empty kettle

-do not put hot kettle on very cold place (floor, stone table), fabric or wooden pad is good choice

-ceramic is generally fragile. So please, do use common sence when using them.

As I have already said, boiling water over the charcoal fire takes my tea experience on new level. And it is not "just" about taste of the water. It is about paying atention to what is going on your tea table. Live energy of fire. It is about being in The Rhythm during your tea time.

For those who are interested, here you can see our available stoves and kettles.

Thank you for the reading!


  1. Petr,

    Awesome post- having the potters point of view and your experimentation with the different sizes are interesting and invaluable information.

    The spherical stove from last post is especially striking! It is very feminine looking and balances nicely the fire inside.



    1. Thanks Matt,

      I was actually inspired by your water and charcaol posts- after reading those I started to pay more atention to all this. So thanks again:)

  2. Actually heat the water for tea with coal is a relaxing and rewarding experience that I would like to practice more often.

  3. Hmm, great stuff!

    I have seen some of the first stoves you made in action and both the stove and the kettle were absolutely lovely. And in means of taste, the water tasted (to me, at least), better than from a tetsubin on a stove (however, I still thought the water boiled in Chao zhou kettle a bit better). I remember the great feeling of holding your kettle in hand and enjoying its texture.

    My current experience seems to hint that the more porous the clay is, the better the resulting water. The Chao zhou kettles are highly porous and at least the one I have is wet to touch after an hour of keeping cold water inside. The fact the kettle is quite thin may be a factor too. The two of your kettles I've seen had much thicker walls than the Chao zhou kettle.

    Anyway, I can surely back up the observation that heating the water outside, in a windy, takes a lot more time. While inside (or in hot summer days), my stove seems to yield the first boiling water in circa 20 minutes, it went up to 60 minutes on a colder autumn day.

    Do you have any tips on cooling the stove down? When I use it outside in a park, I don't always want to wait two hours until it gets cool enough to carry it back home... I generally pour water over it, but it sometimes cracks a bit.

  4. Hi Jakub,

    Thank you for your comment!

    Porous clay will always affect water more. But it also means that the clay have to be better or lets say right- it can also give taste which you are not going to like. Does your CHaoZhou kettle leak?

    Lately, I realized that the more charcoal you use the quicker boil you will get. It is quite obviouse, I know. But when I am outside I just load much more charcoal, and alternatively feed the fire, and the boiling is pretty quick.

    Tips for cooling down? hm, I would say waiting:) I usually use them around the house and I dont have problem to bring it inside if I need. I can also take the sieve out, then it cool down quickly. Wind and air- water is too sadistic to my taste.

    Happy day

    1. Hi,
      indeed, porous clay with bad taste is not what one wants.

      No, I would not say the kettle leaks really. However, it has a tendency to ejaculate when the water reaches boiling state, so I have to fill the kettle less than full or put something under it :)

      Do you have any tips concerning charcoal? Do you think that the aroma of charcoal may affect the taste of water?

    2. I am not sure if aroma affect the taste, but rather quality of the charcoal. As you know, in China, Korea and especialy in Japan there are special woods and technique how to make the right charcoal for tea water. And I belive it is not just a game...But I never made side by side testing of the same water heated with different charcoals.

  5. And now I am very curious about taste of water from your tetsubin. Doupě is very far away from me, Chocerady was closer. But if I will be near sometime, I will try to arrange a meeting, I really want to taste "old" water from old tetsubin.

    Nice writing.

    1. I will be happy to share a cup of tea with you. Just let me know...


  6. This is really a nice and informative, containing all information and also has a great impact on the new technology.

  7. I can see that you are an expert at your field! I am launching a website soon, and your information will be very useful for me.. Thanks for all your help and wishing you all the success in your business.

  8. I was reading your article and wondered if you had considered creating an ebook on this subject. Your writing would sell it fast. You have a lot of writing talent.Hot water Heating Systems


  9. I think your article is very helpful for me.
    Thank you for sharing your content with us. It's always great when we get The Things What We Prefer For in our comfort zone so I prefer having facial
    at home for easy and healthy skin!
    Hibachi Charcoal Burner