Sep 17th 12 10:02 pm
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Mineral Deposits On Bottom Of Teapot

by thenarfer » Sep 17th 12 10:02 pm

Hello, TeaChaters!

I've enjoyed reading many of the threads here on TeaChat. Today it's my turn to ask a question:

About two months ago I bought my first teapot (Tetsubin cast iron) which I use solely to boil water for my teas. The first weeks I only used it with tap water; then I read that the choice of tea water is supposed to be important for the taste of the teas. I had also noticed a slight mineral deposit at the bottom of the teapot (no picture).

I decided that bottled water was worth a try, so I decided to buy Vittel water. After boiling about 5 pots I noticed small "floaters" on the surface of the water which stayed there during the whole heating process (Picture #1). When the pot dried out, the floaters formed crystals at the bottom of the pot (Picture #2) and on the spout (Picture #3).

I checked the label of the bottle (Picture #4), but could not tell much from it.

After I used up all the bottled water (9 liters) and switching back to tap water again (Picture #5). The floaters were now gone! I decided to scratch the deposits a bit (Picture #6). Today, about 2 weeks since I ran out of bottled water, I noticed a piece from the deposits had broken off (Picture #7).

I've decided not to clean out the pot since I read different things:
- minerals being good for the flavor of the water
- not to disturb the deposits (wipe the bottom of the pot)
- not to switch water (which I did)
and because I thought it was interesting to see it develop.

What does your water boiling vessel look like on the inside?

What do you do about the mineral deposits, if this has happened to you?

How could this positively/negatively influence the taste of the tea?

PS: I have no idea if my tap water is hard or not. Note that mineral deposit increased when I used bottled water and decreased again when going back to tap water.
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Sep 17th 12 10:04 pm
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Re: Mineral Deposits On Bottom Of Teapot

by thenarfer » Sep 17th 12 10:04 pm

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Sep 18th 12 6:17 am
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Re: Mineral Deposits On Bottom Of Teapot

by jayinhk » Sep 18th 12 6:17 am

What you're seeing is limescale, which is perfectly normal: it implies you have less dissolved calcium in your tap water than in Vittel. Your tap water is probably fine. Yes, mineral content will affect flavor due to it affecting the solubility of different compounds in the tea. You can remove it with vinegar if you really want to, but it's entirely harmless and merely an aesthetic concern.

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Sep 19th 12 5:16 pm
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Re: Mineral Deposits On Bottom Of Teapot

by BioHorn » Sep 19th 12 5:16 pm

These deposits are completely normal. Your post motivated me to re-shoot my tetsubin after about a year of use. Our Cleveland water seems to have moderate to high scale.

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Nov 20th 12 3:40 pm
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Re: Mineral Deposits On Bottom Of Teapot

by tkellyd » Nov 20th 12 3:40 pm

Hello thenarfer:

Judging by the handle of your pot, it looks like you've got an enameled teapot and using it for a tetsubin. There is a difference. Enameled pots are not made to be heated on the stove. I am not sure how this will affect your health, but eventually the enamel will come apart from the iron.

BioHorn's pot is a true tetsubin, seen with mineral deposits. it is made to be heated on the stove.

Best,

- T

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Nov 20th 12 4:41 pm
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Re: Mineral Deposits On Bottom Of Teapot

by AdamMY » Nov 20th 12 4:41 pm

tkellyd wrote:Hello thenarfer:

Judging by the handle of your pot, it looks like you've got an enameled teapot and using it for a tetsubin. There is a difference. Enameled pots are not made to be heated on the stove. I am not sure how this will affect your health, but eventually the enamel will come apart from the iron.

BioHorn's pot is a true tetsubin, seen with mineral deposits. it is made to be heated on the stove.

Best,

- T
I am not sure you can completely make that assumption based on the handle alone. you would honestly need to inspect the pot personally to figure out if it is enameled inside. While yes that type of handle is more often used on tetsubin that are enameled inside, I have seen ones with that handle that were pure cast iron.

In fact I have one with that type of handle that while it was billed as a teapot and came with an infuser basket, I really really looked at it, when I saw it in the store, and saw no sign of enamel on the inside I decided to take a 20 dollar gamble, and took it home, used it as a kettle a few times, and the inside actually started to rust ever so slightly. confirming my suspicions that it was not enameled.

So you can not tell by the handle alone, ( but I have often thought the handle would be the first place to go on my "kettle").

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Nov 20th 12 7:57 pm
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Re: Mineral Deposits On Bottom Of Teapot

by tkellyd » Nov 20th 12 7:57 pm

Hello AdamMY:

You may be right about my assumption on the pot not being a true tetsubin. But as I see it, not only is the handle suspect, so too is the shine on the bottom of the pot in the first picture. I have not seen a new (or for that matter, old) tetsubin with a shiny interior. Certainly my new Kunzan was not shiny on the inside. No antique or vintage tetsubin that I own looks shiny on the inside.

Also, for a pot that is two months old, there are no orange or white mineral spots on the inside bottom. Even you acknowledged that your own pot rusted after using it a few times. There are no katamochi plugs that I can see either. And it looks as though the enamel is flaking off (see picture #7). So I'm sticking to my original assumption of teapot.

Best,

- T

Dec 12th 12 4:00 pm
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Re: Mineral Deposits On Bottom Of Teapot

by thenarfer » Dec 12th 12 4:00 pm

You're right, tkellyd.

I've used it for boiling water for half a year, but no damage to the enamel yet. I will stop using it now that I know better.

Looking for a real tetsubin now.

Thanks for saving my health :-)

Mar 20th 20 10:35 pm
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Re: Mineral Deposits On Bottom Of Teapot

by RakhMT » Mar 20th 20 10:35 pm

Glad to finally post after many years of reading threads on the site. I recently (last September) went to Japan, and during my time there went to an antique market in Osaka on the look for a tetsubin. I found one that was within my price range after a couple days!
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Now, it has for sure seen some use, in fact it had quite a buildup of scale already when I purchased it, and some general rust - not really well taken care of, but I like restoring things, so I thought I'd come home and give it some green tea baths and see how it goes...

It has been a challenge, but the water, even with the rust, tastes really smooth and light and sweet as I expected - definitely enjoy using it. So, as you can see from pics, it still has some rust restoration to go...

My real question here is the scaling is not a pure white, in fact it is almost greenish. I didn't really realize this till a part of it flaked off, and then some really white scaling began reforming where it had been, showing me the contrast. And now I wonder... is it safe to use this tetsubin?

I don't know anything about it's history or use, like what water, what time frame, and where, which makes me feel a bit weary lately for using it vs. setting it aside as just decoration.

Could the scaling on an antique pot from Japan potentially be harmful to my health?
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