02 October, 2010

The Aging Tetsubin II

Has it really been over two years since we bought our tetsubin?  Time flies!  I think that we bought it from Artistic Nippon, and it has served us very well.  I think it's a perfect pu'er pot.  It brings out the mineral-like characteristics of the tea, and swells it nicely.  

(Silver kettles are not really my thing - and we don't drink a huge amount of wulong.)

Here's our little baby when it was newly arrived, as described in "Nembu Tekki":

Tetsubin 2010
The original kettle

As yet unaffected by use!  Note the particularly clean spout, shown above.  After one year, I took the following photograph (from "The Aging Tetsubin"), in which you can see some chalk accumulating:


Tetsubin 2010
The spout after one year

Now our pot is coming on for being two-and-a-half years of age, and it has quite a build-up:


Tetsubin 2010
The spout after two years

However, most interesting is what's been happening on the inside.  Shown below is the original pot - note the orange spots of rust that came with it (and which are entirely normal for tetsubin), and the central mark which is a result of the fabrication process:


Tetsubin 2010
The original interior

After one year, it looked as shown below, where the rust-spot has grown to cover most of the fabrication blob, and where some chalky sediment has been accumulating:


Tetsubin 2010
The interior after one year

Now, after two years of heavy use, the base is almost entirely coated:


Tetsubin 2010
The interior after two years


...which we can see a little more clearly if we zoom in:


Tetsubin 2010
Detail of the interior, after two years

I am very careful not to disturb the interior of the kettle - we pour water in, pour water out, and dry it by leaving it on the warm hob for a moment after each session.  So, the above has accumulated simply through use - between sessions, it sits entirely dry.

We use spring water for almost all of our sessions - had we used the tap water here, it would no doubt be several orders of magnitude more white.  Even with "good water", the process is obvious.

So, don't fear a little chalk or the odd spot of rust.  I remember seeing some old kettles in which the sediment had formed a thick mat inside the kettle.  I rather like it; it is like the patina on a teapot - a sign of use.

18 comments:

Simeon ( Tofu Miso ) said...

Hi Hobbes , have the characteristics of the water your tetsubin produces changed since it was new ? I can remember you saying that when compared side by side to Nada's antique tetsubin , your tetsubin produced water that was a little rougher and not quite as sweet , thick and deep as the antique one . I'm thinking about purchasing a tetsubin myself . All the best !

Hobbes said...

That's a difficult one, because the changes are so gradual! It would need another comparison to determine for sure. It does taste good, nonetheless :)

Good luck with your purchase - please let us all know how you get on. Where will you buy it?


Toodlepip,

Hobbes

MarshalN said...

Actually -- it depends entirely on what kind of water your local source uses. Where I used to live, after a whole year of use (filtered, that is) I got nothing in my tetsubin. Now, after moving here, my tetsubin is starting to show whiteness in the interior. Since you use spring water, the amount of minerals that gets left behind is probably much higher than what you would get with filtered tap water, actually.

Simeon ( Tofu Miso ) said...

If I decide to go for a new tetsubin I thought either Hojotea or Artisticnippon ( Hojotea have a very detailed , informative and interesting section on their website about tetsubins ). If I decide to go for an antique one ------ I thought the Moon and Stars tetsubin from Nada , although this would just about cripple the tea budget !

DK said...

Rust is still bad in larger quantities, right? I thought too much rust would make the kettle crack or leak, and the layer of white sediment was supposed to slow down or prevent rusting.

I also wonder if the sediment reduces the tetsubin's effect on the flavor of the water, since less water is touching the iron surface.

Jamus said...

We accept others with their flaws and blemishes. Why wouldn't we extend the same for our wares? ^__^ I think it's beautiful.

best wishes,
jamus~

Asiatic Fox said...

I completely agree with Jamus.

Btw, you should see my teacup:
http://asiaticfox.deviantart.com/gallery/#/d2yfb8e

It's on its way to maturity. I can't wait until the whole cup is completely brown inside. Then it will truly be a thing of beauty.

Jason said...

Dear Hobbes and All,

The white build up is Calcium Carbonate(CaCO3) that precipitates out of water at high temperature.

Calcium Carbonate is a strong base and is technically mildly salty (it interacts with the salt taste receptors on ones tongue).
In my experience, I have found that waters with a higher calcium content have a slight sweet taste.

In precipitate form the Calcium Carbonate would have a very chalky mouth feel; while in solution (aqueous) it actually gives water and tea umami (to be precise, it stimulates the umami taste receptors, a distinct group).

Calcium Carbonate would be ineffective at combating rust in a wet environment as it likely to redissolve with disturbance, or just chunk off into your tea without.

This Research brought to you by the Penn State GongFu Cha Club and future Institute!

All the Best,
Jason M. Cohen

Rob said...

Hi, Do you have any pictures of how the bottom of your tetsubin kettle(exterior) looks like? does it rust alot?

Nick Dilks said...

This is a timely discussion! I have just returned to the UK after using my new tetsubin in Taiwan for 6 months. Whilst there, there was zero white deposit and zero rusting. The water used these was picked up by a local man and sold at the very reasonable rate of 40p for 20 litres! However, after returning to the UK and using Co-op Fairbourne Springs mineral water for a week a lot of chalky white build up crept over most of the tetsubin base. This continued when I switched to Sainsbury's Still Scottish mountain water (both I see now have a 55mg/litre Calcium concentrate. Over the last week, I switched to water I collected myself from a public spring in Malvern and the rate has slowed down.

The rusty orange/brown rusting spotting has spread too, and I am still a little alarmed by this.

John's comments on Calcium Carbonate are very useful, as is the whole article, which once again has helped me with a couple of concerns docking again in the UK.

I hope to report in in the future to say that my tetsubin is OK! Thanks for the reassurance :-)

Hobbes said...

Dear Nick,

It's heartening to read that I'm not the only one battling with Co-op's "Fairbourne Springs"! My tetsubin is rather white these days; I should post an update. :)


Toodlepip,

Hobbes

Nick Dilks said...

Very interesting occurrence . . . After two weeks of switching to Malvern water (and now filtered municipal water) the white at the bottom of my tetsubin is receding by the day! The rust is still proliferating though, which is a shame. Hope she'll be OK!!! By the way, I'd love to come and have a cup of Tea with you some time. I'm just back after a few years in Asia and it would be great to eet another Tea-lover :-)

Hobbes said...

Dear Nick,

A tea session would be a great idea - we should also invite the locals! (I.e., The Jakub and Apache.)


Toodlepip,

Hobbes

Jakub Tomek said...

I'd be all for that :)
Jakub

nada said...

did someone mention a tea party?

Hobbes said...

Its nice to see the (tea) party enthusiasts popping up - let's organise!


Toodlepip,

Hobbes

Jamus said...

*crawls out of the woodwork and waves*

I'd have a rather large puddle to hop over.

jamus~

Nick Dilks said...

Well, this is proving to be a lovely idea! I am free on Sunday 20th & 27th of July and August 3rd. Do any of those work for you? If not, suggestions, please. My email is livingteauk@gmail.com, if you wish to discuss finer details etc. I will bring down a few samples of the puerhs I have gathered whilst out in Asia these last few years. Really looking forward to meeting
:-)