Comparison of 2 old and 1 new tetsubin

 

 A reader recently asked me to find him a new Japanese tetsubin. The nicest one I found (above on the right) reminds me of the 'dragon tetsubin' I used to have eight years ago! So, I even bought a second one in case someone else needs one! In the meantime, this gives me the opportunity to test and compare it with the 2 other tetsubin I have, which are both old.

The test is fairly simple. After cleaning this new tetsubin several times, I boiled water with each of them to compare the taste of their respective hot waters.

 On the left, the water turns out a little bit yellow and I can spot several small spots of metal at the bottom of the cup.

This water comes from this lovely shaped tetsubin with copper top. I especially like the curved handle. It looks elegant and provides a better grip.

The outside of the tetsubin is in good shape.

The reason for the yellow color of the water is that it's very rusty inside.

The bottom is in good shape, though. 

So, the problem comes for the inside. At the very bottom, the rust is a little bit more red and doesn't seem very thick. The biggest layer of rust is higher. I think I should try to remove it with a small sander. Boiling water often in it has helped, but hasn't cured it.

The water tastes soft at first, but quickly develops a strong rusty taste that one can almost smell!
I'm less concerned with the red rust on the bottom than the grey rust above. (The red rust seems active and similar to my other tetsubin, while the grey rust seems dead).

Here is the interior of the second old tetsubin (in the middle). It's the one I use regularly. There's also some fresh (red) rust, but much less than in the first.

This rust had no negative impact on the taste of the water. The water tasted very soft and clean. Excellent!

For the new Iwachu tetsubin, I made sure that the interior isn't covered with any glazing. I want the water to be in direct contact with the iron, so that it can benefit from its interaction.

Inside the new tetsubin

This tetsubin weighs 1.75 kg for a maximum volume of 1.4 liters.

This rough surface requires a good, gentle cleaning with rice water. Then, I boiled several times water in it, until the water that came out looked transparent.

Bottom of the new tetsubin

The result is hot water that doesn't taste as soft as the second tetsubin. It has some slight roughness and a young metallic/sparkling taste. There's more activity in the mouth, which would be a good fit with unroasted Oolongs or raw puerh.

I prefer the pure and soft feel of my regular tetsubin, but this new tetsubin has a better taste than more rusty tetsubin. So, age alone doesn't say much about the quality of the water.

Refined fixation for the handle

This comparison also shows that the regular use of a tetsubin is one of the best way to improve its performance. The more it's used, the less residues will come out. Thus, the modern tetsubin will loose its rough metallic taste over time. (This is what happened to my dragon tetsubin).