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Mar 12th 16 8:08 pm
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Kyusu, inside coating wearing off

by Balthazar » Mar 12th 16 8:08 pm

About six years ago I bought an inexpensive kyusu-pot. I've probably used it 2-3 times per week for five of those years, so it's been a dutiful little servant and I've definitely gotten my money's worth out of it.

The reason why I'm writing this post is that over the last year or so it seems like the internal coating has started to wear off. Have a look at this photo:

http://i.imgur.com/MDWhuQQ.jpg

I'm guessing the brown spots are the underneath clay. In terms of the taste of the brews, I haven't noticed any changes. What I'm wondering is if the black coating might be unhealthy to consume, even if it's only wearing off at a very glacial pace.

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Mar 12th 16 8:39 pm
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Re: Kyusu, inside coating wearing off

by Midwinter_Sun » Mar 12th 16 8:39 pm

Was the original glaze ( coating ) the blue color?

If it is glaze coming off/flaking, I would stop using this pot.

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Mar 12th 16 8:46 pm
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Re: Kyusu, inside coating wearing off

by Balthazar » Mar 12th 16 8:46 pm

Yup. The coating is actually black, although it looks blueish on the photo. I've never actually found flakes of coating in my tea, so they must be tiny.

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Mar 12th 16 9:50 pm
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Re: Kyusu, inside coating wearing off

by Midwinter_Sun » Mar 12th 16 9:50 pm

Balthazar wrote:Yup. The coating is actually black, although it looks blueish on the photo. I've never actually found flakes of coating in my tea, so they must be tiny.
Well, the kidneys do not appreciate them no matter the size.
If You want to get extra motivation to retire the pot, put some acidic boiling water in there ( a glass of hot water and a spoon of vinegar or lemon juice will suffice) , let stand for 8 hours, pour out into a clean glass and look at the particles through bright light.

Unglazed pots sometimes have slight flaking from accumulated tea patina, but that is quite different from the situation You are dealing with.

What were You thinking as far as replacement?

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Mar 12th 16 11:32 pm
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Re: Kyusu, inside coating wearing off

by Drax » Mar 12th 16 11:32 pm

So, it's hard to tell from the photo -- but are you certain that the brown stuff is *under* the black? And that it's not just mineral deposits or tea stains that have accumulated over the years?

Just from the photo, that's what I would have guessed it was first.

If the are just mineral deposits or tea stains, the vinegar/lemon-juice that MS suggested would probably remove them...

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Mar 13th 16 4:36 am
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Re: Kyusu, inside coating wearing off

by pizzapotamus » Mar 13th 16 4:36 am

Echoing what Drax said, just from that photo I'd have thought it was dark clay with lots residue from brewing. Especially as it looks a bit like it might be one of these tokoname dragonfly teapot https://www.o-cha.com/tokoname-dragonfl ... ory_id=164 which I definitely would have guessed to be uncoated on the interior.

Edit: I've added a photo of my interior bottom of first, oldest and mankiest pot, started off with dark almost black coloured clay and now it's stained to that. Which looks fairly similar. If it isn't actually a glaze or other coating flaking off I'm sure you could clean it up some if you feel the need but I'd be in a rush to soak it long term with anything.
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Mar 15th 16 5:52 pm
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Re: Kyusu, inside coating wearing off

by Balthazar » Mar 15th 16 5:52 pm

Well, this goes to show how much I know about Japanese pottery :)

It is indeed the tokoname dragonfly-pot. I actually have no basis whatsoever for claiming that it's coated, and by reading the last two posts I'm betting it's not. Aesthetically I have no problem with that's going on (I actually like that it's "changing"), it was more a concern that what I thought was coating was wearing off and floating into my body.

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Mar 15th 16 7:57 pm
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Re: Kyusu, inside coating wearing off

by Midwinter_Sun » Mar 15th 16 7:57 pm

If it is unglazed inside, enjoy the fine tea patina :mrgreen:
It should continue being a reliable servant!

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Mar 16th 16 12:33 am
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Re: Kyusu, inside coating wearing off

by Drax » Mar 16th 16 12:33 am

Hey, well on the positive side, you can continue to enjoy brewing with no concerns about consumption of a deteriorating interior (say that 5 times quickly :lol: )