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Jan 7th 17 7:35 pm
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Clay teapots and waterproof film?

by jayinhk » Jan 7th 17 7:35 pm

I've long suspected this was the case with clay teapots--that a waterproof film forms on the pots, and that the film is made up of fatty acids from tea. A member from China suggested we should be scrubbing the inside of our pots out regularly for health reasons.

I sometimes wonder if what makes different clays perform differently is primarily varied heat retention, as one of our members suggested to me one day. I think there is still some absorption regardless of how much tea you brew; my heavily used shuipings still 'hang water' regardless of how much they're used and how much of a film forms. Porcelain will never do that.

http://www.jfda-online.com/article/S102 ... 5/abstract

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Re: Clay teapots and waterproof film?

by kyarazen » Jan 8th 17 1:15 am

jayinhk wrote:I've long suspected this was the case with clay teapots--that a waterproof film forms on the pots, and that the film is made up of fatty acids from tea. A member from China suggested we should be scrubbing the inside of our pots out regularly for health reasons.

I sometimes wonder if what makes different clays perform differently is primarily varied heat retention, as one of our members suggested to me one day. I think there is still some absorption regardless of how much tea you brew; my heavily used shuipings still 'hang water' regardless of how much they're used and how much of a film forms. Porcelain will never do that.

http://www.jfda-online.com/article/S102 ... 5/abstract
different clays different degrees of absorption. it is possible to patinate an yixing pot without tea but only with purely hot water :D

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 8th 17 3:48 am

kyarazen wrote:
jayinhk wrote:I've long suspected this was the case with clay teapots--that a waterproof film forms on the pots, and that the film is made up of fatty acids from tea. A member from China suggested we should be scrubbing the inside of our pots out regularly for health reasons.

I sometimes wonder if what makes different clays perform differently is primarily varied heat retention, as one of our members suggested to me one day. I think there is still some absorption regardless of how much tea you brew; my heavily used shuipings still 'hang water' regardless of how much they're used and how much of a film forms. Porcelain will never do that.

http://www.jfda-online.com/article/S102 ... 5/abstract
different clays different degrees of absorption. it is possible to patinate an yixing pot without tea but only with purely hot water :D
Just with calcium and other minerals? I guess so, I try to fight the limescale with my brush and rubdowns :)

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Re: Clay teapots and waterproof film?

by theredbaron » Jan 8th 17 6:38 am

jayinhk wrote:
kyarazen wrote:
Just with calcium and other minerals? I guess so, I try to fight the limescale with my brush and rubdowns :)

Lime scale, as in white scale? That would indicate a water problem, using water that is too hard.
My pots, depending on surface, develop over the years build up of tea particles in some areas such as near the rim and where the handle and spout connects with the pot, to some degree. But i find that this only adds to the beauty of the pots, contrasting with the deep shine on the surface.
And yes, some clays do develop patina much quicker than others, beginning at times already after the first brews.

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 8th 17 6:43 am

theredbaron wrote:
jayinhk wrote:
kyarazen wrote:
Just with calcium and other minerals? I guess so, I try to fight the limescale with my brush and rubdowns :)

Lime scale, as in white scale? That would indicate a water problem, using water that is too hard.
My pots, depending on surface, develop over the years build up of tea particles in some areas such as near the rim and where the handle and spout connects with the pot, to some degree. But i find that this only adds to the beauty of the pots, contrasting with the deep shine on the surface.
And yes, some clays do develop patina much quicker than others, beginning at times already after the first brews.
Even after four years of heavy use here, I got a very light white ring around the knob and where the lid meets the body (soft water here). I removed it easily with a few rubdowns after tea sessions. I was asking if calcium deposition (limescale) was what kyarazen meant by patina on pots with plain water. I brush my pots during tea sessions and rub them down once in a while now so I get a very even patina and shine.

https://www.instagram.com/p/BOyq944jBTc ... fehk&hl=en < --- pu erh pot

https://www.instagram.com/p/BN6rbOCAkDe ... fehk&hl=en < --- high fire oolong pot

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Re: Clay teapots and waterproof film?

by theredbaron » Jan 8th 17 7:17 am

jayinhk wrote: Even after four years of heavy use here, I got a very light white ring around the knob and where the lid meets the body (soft water here). I removed it easily with a few rubdowns after tea sessions. I was asking if calcium deposition (limescale) was what kyarazen meant by patina on pots with plain water. I brush my pots during tea sessions and rub them down once in a while now so I get a very even patina and shine.

Calcium deposition is never meant to be patina. What he mean was what he said - that some clays develop patina - meaning the deep shine that pots develop - very quick only with hot water.
For example, the grapes and squirrels pot i recently unearthed in my storage, seems to be made from such a clay.

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 8th 17 7:47 am

theredbaron wrote:
jayinhk wrote: Even after four years of heavy use here, I got a very light white ring around the knob and where the lid meets the body (soft water here). I removed it easily with a few rubdowns after tea sessions. I was asking if calcium deposition (limescale) was what kyarazen meant by patina on pots with plain water. I brush my pots during tea sessions and rub them down once in a while now so I get a very even patina and shine.

Calcium deposition is never meant to be patina. What he mean was what he said - that some clays develop patina - meaning the deep shine that pots develop - very quick only with hot water.
For example, the grapes and squirrels pot i recently unearthed in my storage, seems to be made from such a clay.
Thanks, but I'll wait for kyarazen's clarification. A patina is developed through use, so calcium deposition developed through use is also patina. Tea stains are also patina. ;)

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Re: Clay teapots and waterproof film?

by stevorama » Jan 8th 17 4:50 pm

There's an interesting article discussing patina here: http://www.kyarazen.com/patina-developm ... xing-pots/

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 8th 17 7:31 pm

Thanks Steve, that answered my question! I hadn't really considered that clay expanded and contracted during use. That explains why some of the teapots' lids fit better when they're in use than when they're cold.

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Re: Clay teapots and waterproof film?

by pizzapotamus » Jan 9th 17 12:28 am

With regards to the movement of water within the spout, wouldn't simply the volume of the water decreasing with temperature be at least as much a factor as the pot expanding?

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 9th 17 6:34 am

pizzapotamus wrote:With regards to the movement of water within the spout, wouldn't simply the volume of the water decreasing with temperature be at least as much a factor as the pot expanding?
I hadn't considered that, but that's a good point. I was thinking the leaves would absorb some, which would lead to the volume falling.

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Re: Clay teapots and waterproof film?

by kyarazen » Jan 9th 17 7:37 am

pot expansion is still the more important factor in surface changes :D although many aspects will contribute to the water level falling.

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 9th 17 7:44 am

Anyone got a micrometer? Would be interesting to see how much a pot really expands :)

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Re: Clay teapots and waterproof film?

by .m. » Jan 14th 17 3:22 pm

jayinhk wrote:Thanks Steve, that answered my question! I hadn't really considered that clay expanded and contracted during use. That explains why some of the teapots' lids fit better when they're in use than when they're cold.
Not sure how does it explain it... When you pour hot water in the teapot, the teapot will be typically hotter than the lid, so it should expand more, and the lid fit would be worse... (unless you're talkin about tight fitting lids) ... :twisted:

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Re: Clay teapots and waterproof film?

by jayinhk » Jan 14th 17 6:40 pm

.m. wrote:
jayinhk wrote:Thanks Steve, that answered my question! I hadn't really considered that clay expanded and contracted during use. That explains why some of the teapots' lids fit better when they're in use than when they're cold.
Not sure how does it explain it... When you pour hot water in the teapot, the teapot will be typically hotter than the lid, so it should expand more, and the lid fit would be worse... (unless you're talkin about tight fitting lids) ... :twisted:
I can't explain it either, but it happens :D

Oh, I pour hot water and tea over my pots. That should make the heat rise and the lid would be just as hot (or hotter) than the body.