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Musings on Yixing ware
As far as gongfu cha goes, what, really, do zi sha clay et
al. do for the tea? I don't imagine ANY ceramic would lose heat so quickly that it would be an issue with 30/45 second brewings, and even if that WERE an issue, a hot water bath should be able to take care of that. Clay is a chemically reactive substance...anything there? .. |
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"dave" > wrote in message ... > As far as gongfu cha goes, what, really, do zi sha clay et > al. do for the tea? I don't imagine ANY ceramic would lose > heat so quickly that it would be an issue with 30/45 second > brewings, and even if that WERE an issue, a hot water bath > should be able to take care of that. > > Clay is a chemically reactive substance...anything there? > . Clays are considered exceptionally non-reactive chemically, especially in the ceramics form, after high-temp treatment, like all pottery would. That is why clay is almost indestructible even geologically. Only very high heating combined with high pressure (we are talking geological scale here) is capable of recrystallizing clays into other alumosilicates. Tea brewing in yixing pots is recommended because of centuries of experience that showed that yixing clay contains almost no heavy metals and its porous structure (yixing "clay" not actually a clay, but a clayey sandstone that is almost 60% quartz, that has to be continuously wetted and additionally weathered for years before usage) yields good tea tang (soup). Sasha. |
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Alex y.com6/9/05
> > "dave" > wrote in message > ... >> As far as gongfu cha goes, what, really, do zi sha clay et >> al. do for the tea? I don't imagine ANY ceramic would lose >> heat so quickly that it would be an issue with 30/45 second >> brewings, and even if that WERE an issue, a hot water bath >> should be able to take care of that. >> >> Clay is a chemically reactive substance...anything there? >> . > > Clays are considered exceptionally non-reactive chemically, especially in > the ceramics form, after high-temp treatment, like all pottery would. That > is why clay is almost indestructible even geologically. Only very high > heating combined with high pressure (we are talking geological scale here) > is capable of recrystallizing clays into other alumosilicates. > Tea brewing in yixing pots is recommended because of centuries of experience > that showed that yixing clay contains almost no heavy metals and its porous > structure (yixing "clay" not actually a clay, but a clayey sandstone that is > almost 60% quartz, that has to be continuously wetted and additionally > weathered for years before usage) yields good tea tang (soup). > > Sasha. Sasha, I was going to question your "needs to be weathered for years before usage" statement, but I notice you are referring to the raw clay pre-potted. This advice would serve for more conventional clays too as they become more maleable, if that's the word, after years of aging. The Chinese had buried their clays for decades before creating objects from them. Perhaps they aged clay and pu'erh together, who knows. Michael > > |
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Clay has been used as a storage vessel by all cultures since time
immemorial. I can't remember if it was used by our hominid ancestors. I remember the Egytians even made a primative battery out of it. Our local history museum has a world class exhibit of pre columbian pottery. I don't think they used heat or wheels. Take any clay, mold it, dry it and it'll last forever till somebody breaks it. If the original poster was thinking of leaching that can occur in unglazed pots. Modern clay has stuff added to it so glazing is a safety precaution. Jim Michael Plant wrote: > Alex y.com6/9/05 > > > > > > "dave" > wrote in message .... > >> Clay is a chemically reactive substance...anything there? > > > > Clays are considered exceptionally non-reactive chemically, especially in > > the ceramics form, after high-temp treatment, like all pottery would. That > > is why clay is almost indestructible even geologically. Only very high > > heating combined with high pressure (we are talking geological scale here) > > is capable of recrystallizing clays into other alumosilicates. .... > > Sasha, > > I was going to question your "needs to be weathered for years before usage" > statement, but I notice you are referring to the raw clay pre-potted. This > advice would serve for more conventional clays too as they become more > maleable, if that's the word, after years of aging. The Chinese had buried > their clays for decades before creating objects from them. Perhaps they aged > clay and pu'erh together, who knows. > > Michael |
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"Michael Plant" > wrote in message ... > Space 6/10/05 > > >> Clay has been used as a storage vessel by all cultures since time >> immemorial. I can't remember if it was used by our hominid ancestors. >> I remember the Egytians even made a primative battery out of it. Our >> local history museum has a world class exhibit of pre columbian >> pottery. I don't think they used heat or wheels. Take any clay, mold >> it, dry it and it'll last forever till somebody breaks it. If the >> original poster was thinking of leaching that can occur in unglazed >> pots. Modern clay has stuff added to it so glazing is a safety >> precaution. >> >> Jim > > Jim, > > If your memory pops back, please let me know which of my hominid ancestors > used clay. Also, I'm thoroughly interested in the Egyptian battery, so if > you come by anything more detailed, I'd love to see it. > > On the heat issue, I beg to differ. Clay unheated will disintegrate. The > physical structure of the clay needs altering by heat to stablize the > vessel. You can do it in a bon fire, but you've got to do it. Otherwise, > mush. > > Michael All known archeological pottery underwent heat treatment one way or another. Otherwise clay sucks the moisture out of the air or soil and disintegrates. The ability of clay minerals to suck water inside their crystallographic structure (up to 100s times its dry volume in montmorillonites, for example) is fixed by high-temp baking (at least 800 Celsius at prolonged times). Drying never gets the intercrystallic "inner" water out of clay, even if you dry it for millions of years in a desert. Even the Shumer clay tablets for writing were baked, although they could have been used in just dried form easier than any cooking utility. The process of baking eliminated the possibility to water the surface and alter the text. Baked tablet text was fixed forever and could be destroyed only with the tablet itself. Sasha. |
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"Michael Plant" > wrote in message > On the heat issue, I beg to differ. Clay unheated will disintegrate. Certainly, but that can take a very long time. >The physical structure of the clay needs altering by heat to stablize the > vessel. You can do it in a bon fire, but you've got to do it. That was a quite recent improvement. Many generations have lived with raw potteries. Even after the heating technique was known, that was considered too costly for everyday objects. > Otherwise, mush. That depends on the material. The clay I got from a riverbed in my village is water-resistant. We used some to make decorative pots that, after drying during a few months, stayed several years in a rainy garden, they were broken and didn't show signs of desintagration. Other types of mud can be kept for ages inside the house. You can glaze or wax them to protect them from liquids. Kuri |
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The earliest examples of fired clay is from the Jomon period in Japan
around 10000BC. The earliest examples in the Americas is Equador around 3500BC. The first civilization of Sumerians used it as a matter of fact but I couldn't find a date for earliest use. The fire remains of Homo Erectus the first hominid to settle Asia is found in clay hearths as a byproduct. I think it was the independent discovery by Homo Sapiens around the world who discovered fire could harden clay as a useful material and not passed down from a lost Atlantis. I've seen three dimensional solid clay objects in Mexico that were cured in the sun and not fired but more adobe or cob like. It's when you move to thin wall you need heat. Jim kuri wrote: > "Michael Plant" > wrote in message > > > On the heat issue, I beg to differ. Clay unheated will disintegrate. > > Certainly, but that can take a very long time. > > >The physical structure of the clay needs altering by heat to stablize the > > vessel. You can do it in a bon fire, but you've got to do it. > > That was a quite recent improvement. Many generations have lived with raw > potteries. Even after the heating technique was known, that was considered > too costly for everyday objects. > > > Otherwise, mush. > > That depends on the material. The clay I got from a riverbed in my village > is water-resistant. We used some to make decorative pots that, after drying > during a few months, stayed several years in a rainy garden, they were > broken and didn't show signs of desintagration. Other types of mud can be > kept for ages inside the house. You can glaze or wax them to protect them > from liquids. > > Kuri |
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I'll take the simple answer here and just say, it keeps heat well. For
those teas that require a super high heat, zi sha is very useful. |
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Quote:
Your answer makes sense, however...with the whole "tea boat" part of the process, as well as the short (15-30 seconds) brew times, is it that much of an issue? Has anyone really checked this out with, say, a thermistor and a computer? Would, say, porcelain in a hot-water bath lose heat quickly enough in those 15-30 seconds, in comparison to zi sha, to make that much of a difference? I begin to think that the "advantages" of Yixing teapots can best be expressed in the following formula: cool + traditional + sexy = Yixing.  I was holding out hope for the whole surface-reaction-of-the-clay thing. Even glass has a slighty acidic surface reaction (this is how electronic pH probes usually work). |
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I haven't been that scientific in my investigations, but I will say
that I drink all of my Chinese tea gongfu style and I have noticed a difference with brewing certain teas. For instance, I got a decent mid-grade Tie Guan Yin that when I brew with a gaiwan, it seems some of the flavor and the scent gets lost, and I think it's partially because the heat escapes quicker using this brewing method. I consider heat as the main variable because I keep the time of the brewings and the amount of tea the same. When I brew it with the yixing pot that I have for my Tie Guan Yin, the flavor and the scent is retained better. I haven't noticed it with the stronger teas like Pu'er or my Nong Xiang TGY, though, which is interesting. Maybe it's just a TGY thing? |
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?> Clay is a chemically reactive substance...anything there?
AC> Clays are considered exceptionally non-reactive chemically, especially in AC> the ceramics form, after high-temp treatment, like all pottery would. That AC> is why clay is almost indestructible even geologically. Only very high AC> heating combined with high pressure (we are talking geological scale here) AC> is capable of recrystallizing clays into other alumosilicates. I've heard of various extreme brewing strategies, Alex. I am still waiting for one which can metamorphose the clay into mica (muscovite in your case, I would suppose). That would be impressive. But, although clay doesn't react easily itself, doesn't it serve as a substrate for other reactions? Couldn't it be a catalyst? If I remember right, the origin-of-lifers now suspect that our great[etc.] grandparents started out as clay scum (yes, I know that this is a good opening line - go for it). DogMa, what do you think? (I think that I couldn't tell the difference between clay, glass or stainless, but my palate isn't very sensitive.) If clay does improve taste, why aren't we partially filling our pots with little fired clay marbles or tori, I suppose, to increase surface area? Best, Rick. |
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"Rick Chappell" > wrote in message
... >?> Clay is a chemically reactive substance...anything there? > > I've heard of various extreme brewing strategies, Alex. I am still > waiting for one which can metamorphose the clay into mica (muscovite > in your case, I would suppose). That would be impressive. > I am surprised that you question that. Actually its quite common in regional metamorphism (but none of that can be found in TX, I guess  Look at the link below under III C. 2.a http://pls.atu.edu/physci/geology/pe...arocks_htm.htm Recrystallization into minerals with which we are familiar: -Quartz (usually doesn't alter, stays quartz but grains may recrystallize into larger size grains of quartz that are visible) -Clays alter into Muscovite & Biotite (micas -- weathering of micas creates clays; so clays are cooked back into micas -- has been demonstrated in research laboratories) -Clays and micas, if alteration is intense enough, may alter into Feldspar and Amphibole (Hornblende) Sasha. "Rick Chappell" > wrote in message ... >?> Clay is a chemically reactive substance...anything there? > > AC> Clays are considered exceptionally non-reactive chemically, especially > in > AC> the ceramics form, after high-temp treatment, like all pottery would. > That > AC> is why clay is almost indestructible even geologically. Only very high > AC> heating combined with high pressure (we are talking geological scale > here) > AC> is capable of recrystallizing clays into other alumosilicates. > > I've heard of various extreme brewing strategies, Alex. I am still > waiting for one which can metamorphose the clay into mica (muscovite > in your case, I would suppose). That would be impressive. > > But, although clay doesn't react easily itself, doesn't it serve as a > substrate for other reactions? Couldn't it be a catalyst? If I > remember right, the origin-of-lifers now suspect that our great[etc.] > grandparents started out as clay scum (yes, I know that this is a good > opening line - go for it). DogMa, what do you think? (I think that I > couldn't tell the difference between clay, glass or stainless, but my > palate isn't very sensitive.) > > If clay does improve taste, why aren't we partially filling our pots > with little fired clay marbles or tori, I suppose, to increase surface > area? > > Best, > > Rick. > > > |
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Quote:
Well, at least I follow the catalytic thing. Quote:
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[various posters]
> Would, say, porcelain in a hot-water bath > lose heat quickly enough in those 15-30 seconds, in comparison to zi > sha, to make that much of a difference? Unlikely. I'd guess that the initial temp drop, mainly a mass effect and most relevant to first steep, dominates. Thin pot has less wall heat capacity, so less initial drop. Heat loss to air is insignificant unless outside of pot is wet. > I begin to think that the "advantages" of Yixing teapots can best be > expressed in the following formula: cool + traditional + sexy = > Yixing. You left out "expensive." > I was holding out hope for the whole surface-reaction-of-the-clay > thing. Even glass has a slighty acidic surface reaction (this is how > electronic pH probes usually work). I don't think so; thin glass is an ionic conductor; the action occurs inside - not the same thing. Very unlikely that clay does any chemistry, especially after rapidly passivating on first steep. > But, although clay doesn't react easily itself, doesn't it serve as a > substrate for other reactions? Couldn't it be a catalyst? Certainly. But the origin-of-life bit occurred under much more extreme conditions, with dilute organics, refreshed clay surfaces, high salt concentrations, electrical discharge, high UV flux, and a few other activating factors. > ... the origin-of-lifers now suspect that our great[etc.] > grandparents started out as clay scum (yes, I know that this is a good > opening line - go for it). DogMa, what do you think? I'll ask my mother - she has some opinions on the scum-like nature of some people's ancestors. > (I think that I > couldn't tell the difference between clay, glass or stainless, but my > palate isn't very sensitive.) Ditto, but I strongly doubt that most "experts" could tell the difference in a blind tasting if temperature and steep time were normalized. Remember that famous wine tasting where blindfolded experts couldn't all tell red from white? -DM -DM |
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Dog Ma /14/05
reply w/o spam > [various posters] >> Would, say, porcelain in a hot-water bath >> lose heat quickly enough in those 15-30 seconds, in comparison to zi >> sha, to make that much of a difference? > > Unlikely. I'd guess that the initial temp drop, mainly a mass effect and > most relevant to first steep, dominates. Thin pot has less wall heat > capacity, so less initial drop. Heat loss to air is insignificant unless > outside of pot is wet. Aha!!!! To bring down the temperature of the tea within, I wet the pot wall without? Cool. > >> I begin to think that the "advantages" of Yixing teapots can best be >> expressed in the following formula: cool + traditional + sexy = >> Yixing. > > You left out "expensive." Yup. > >> I was holding out hope for the whole surface-reaction-of-the-clay >> thing. Even glass has a slighty acidic surface reaction (this is how >> electronic pH probes usually work). > > I don't think so; thin glass is an ionic conductor; the action occurs > inside - not the same thing. Very unlikely that clay does any chemistry, > especially after rapidly passivating on first steep. Like unto rocks in the kettle presumably. Funny that I had a similar discussion in one of the pet mouse groups this morning about passivating on the first steep. Quite a coincidence. Oh, that was pAssivating. Never mind. Disregard. > >> But, although clay doesn't react easily itself, doesn't it serve as a >> substrate for other reactions? Couldn't it be a catalyst? > > Certainly. But the origin-of-life bit occurred under much more extreme > conditions, with dilute organics, refreshed clay surfaces, high salt > concentrations, electrical discharge, high UV flux, and a few other > activating factors. > >> ... the origin-of-lifers now suspect that our great[etc.] >> grandparents started out as clay scum (yes, I know that this is a good >> opening line - go for it). DogMa, what do you think? > > I'll ask my mother - she has some opinions on the scum-like nature of some > people's ancestors. > >> (I think that I >> couldn't tell the difference between clay, glass or stainless, but my >> palate isn't very sensitive.) > > Ditto, but I strongly doubt that most "experts" could tell the difference in > a blind tasting if temperature and steep time were normalized. Remember that > famous wine tasting where blindfolded experts couldn't all tell red from > white? So, you've been nibbling on steel and glass and clay, have ye? Oh, you refer to tea steeped in them. Sorry, my love and understanding of chemistry and physics permits no further elicidation. Perhaps Jim can add. Michael |
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SS is indestructable but spout acts like fire hydrant. Clay is
generally heavy and noted for handling problems. Glass is elegant but fragile. I think a pot is aesthetics and ergonomics. I'm a big fan of the agony of the leaves. I am surprised at how lifeless some teas are with the Indians being at the top. There was some cheap Darjeeling white on Ebay yesterday and I forgot to bid. I came across some 750ml glass pots in plastic cradle with metal infusers which I'll remove and use as teacups. They were cheap at a couple of bucks each. I also got some Chinese tall cups,handle,infuser,lid for the same price but came in the boxes for convenient storage. For this style I recommend the flat lid which can hold the infuser. Jim Michael Plant wrote: .... > So, you've been nibbling on steel and glass and clay, have ye? Oh, you > refer to tea steeped in them. Sorry, my love and understanding of chemistry > and physics permits no further elicidation. Perhaps Jim can add. > > Michael |
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"Dog Ma 1" (reply w/o spam)> writes:
> [various posters] > > Would, say, porcelain in a hot-water bath lose heat quickly enough > > in those 15-30 seconds, in comparison to zi sha, to make that much > > of a difference? > > Unlikely. I'd guess that the initial temp drop, mainly a mass effect > and most relevant to first steep, dominates. Thin pot has less wall > heat capacity, so less initial drop. Heat loss to air is > insignificant unless outside of pot is wet. So when a gongfucian pours a bit of hot water over a Yixing pot just after setting the lid, he's *cooling* the brew (whether he knows it or not?) /Lew --- Lew Perin / http://www.panix.com/~perin/babelcarp.html |
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Lewis Perin wrote:
> So when a gongfucian pours a bit of hot water over a Yixing pot just > after setting the lid, he's *cooling* the brew (whether he knows it or > not?) Certainly could be. Soaking the pot with water at the same temp as the contents can't warm it, and rapid evaporation from the rough surface probably drops a few degrees in a few seconds. Water has an enormous latent heat of evaporation. But I suspect that it's just another empty (if charming) ritual, or a carryover from another style - say, using an un-preheated pot. -DM |
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Dog Ma /15/05
reply w/o spam > Lewis Perin wrote: >> So when a gongfucian pours a bit of hot water over a Yixing pot just >> after setting the lid, he's *cooling* the brew (whether he knows it or >> not?) > > Certainly could be. Soaking the pot with water at the same temp as the > contents can't warm it, and rapid evaporation from the rough surface > probably drops a few degrees in a few seconds. Water has an enormous latent > heat of evaporation. But I suspect that it's just another empty (if > charming) ritual, or a carryover from another style - say, using an > un-preheated pot. > > -DM > > As we are aware, the core of being is an empty ritual -- to mix metaphors -- but no, there is purpose. Pouring water over the outside of the filled teapot serves to clean off spotting and homogenize stains. In addition, and more importantly, the pouring causes the tea water on the inside to move around in its attempt to commune with the water on the outside, causing a further mixing. Finally, I've noticed that pouring hot water over the filled pot facilitates an eructation of the pot lid in an oft' bemusing way. Michael |
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Michael Plant > writes:
> Dog Ma /15/05 > reply w/o spam > > > Lewis Perin wrote: > >> So when a gongfucian pours a bit of hot water over a Yixing pot > >> just after setting the lid, he's *cooling* the brew (whether he > >> knows it or not?) > > > > Certainly could be. Soaking the pot with water at the same temp as > > the contents can't warm it, and rapid evaporation from the rough > > surface probably drops a few degrees in a few seconds. Water has > > an enormous latent heat of evaporation. But I suspect that it's > > just another empty (if charming) ritual, or a carryover from > > another style - say, using an un-preheated pot. > > As we are aware, the core of being is an empty ritual -- to mix > metaphors -- but no, there is purpose. Pouring water over the > outside of the filled teapot serves to clean off spotting and > homogenize stains. In addition, and more importantly, the pouring > causes the tea water on the inside to move around in its attempt to > commune with the water on the outside, causing a further > mixing. Finally, I've noticed that pouring hot water over the filled > pot facilitates an eructation of the pot lid in an oft' bemusing > way. Wow, there must be powerful forces at work in that little pot. I can't remember eructating anything solid in my whole life. /Lew --- Lew Perin / http://www.panix.com/~perin/babelcarp.html |
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Thanks guys....
I had almost forgotten how much fun good people can be in a forum. All that aside its not about heat loss directly. Its about heat retention. The pot is properly heated first and properly timed reheating makes the pot hotter each time or if properly timed maintains an optimum temp as you pao. This is because it is preheated and doesn't have to rise as much in temp. Nothing else in the world matches good yixing pots for this. It will never get as hot as the water inside for reasons well covered here already. That keeps all that soup mixing and eructating going in an optimum fashion if you are a good brewer. I'm not even sure what eructation is but your comments make me hope all my pots do it. Regards... Renny Quote:
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