Yixing clay that is suitable for yancha

[kyarazen]

it is a fine balance, if you understand the properties of a pot and complement it with appropriate brewing procedures, you can use that single pot for any tea and achieve good results. I'm not denying that clay does have effects on the brew, since i've been using japanese clays that are more leachy than oxidation fired yixings. but over time if you have really nice clay, the internal surface changes over usage, the pores and crevices get stained and filled, this activity decreases. if a pot were to be relied on the leaching properties, then its property is not long lasting. (this leachy thing can be augmented by either using a better kettle, or using different types of water with different mineral contents to make up for it). very porous or not well fired pots can be rather absorptive and can ruin a tea's aromatics, the patina is hard to raise, but if you use it patiently for incredibly long amounts of time, they will stop being robbers as the interior surface gets blocked by tea stains or water residues.



the monotonic decrease with the shape of the pot is what that makes a pot unique. the clay benefits and properties, are much more short lived than the effects of the shape and thermal properties.

I saw the nice discussion on thermal properties on your blog I agree that heat retention is very important and shape and size can both affect it (they both alter the surface to volume ratio). One question I have about that though is this: it seems that there is more room to alter the heat to which the tea is exposed by adjusting water temperature, steeping time and/or pouring hot water on the pot. Unless there's reason to believe that a monotonic decrease in temperature with a specific shape is very important for the outcome, it seems that suboptimal heat retention of a pot for a certain tea would be easier to remedy than undesired effects of the clay. What are your thoughts?

[BW85]

[quote="kyarazen"

the monotonic decrease with the shape of the pot is what that makes a pot unique. the clay benefits and properties, are much more short lived than the effects of the shape and thermal properties[/quote]

Is cleaning out the inside of your pots something you plan on doing throughout the years? To maintain the catalytic nature of the clay?

[kyarazen]

[quote="kyarazen"

the monotonic decrease with the shape of the pot is what that makes a pot unique. the clay benefits and properties, are much more short lived than the effects of the shape and thermal properties

Is cleaning out the inside of your pots something you plan on doing throughout the years? To maintain the catalytictic nature of the clay?[/quote]

nope!! the shape and therm properties is important, but the external patina even more! i derive great pleasure in nurturing pots and seeing the patina develop. red clay, dark clay, light clay have different heat capacities and radiatively lose heat differently.. this physical property doesnt change with time.

[BW85]

I'd be careful to not get too hung up on red vs purple/brown clay and make any rules about that comparison. Truly great clay will perform well for darn near any tea. The following pot makes a phenomenal round of green TGY, and preserves the higher notes and aromas of the floral tea almost just as well as a high quality higher fired hong ni pot of similar size and shape. In addition to preserving those higher notes, the teapot also makes the mouthfeel better than the hong ni pot, and seems to increase the lingering aftertastes better. I've even had green TGY from a beautiful duan ni pot which came out amazingly well. Great clay is great clay, regardless of the color. That being said, great clay does not come from $50 pots nowadays, but there's nothing wrong with experimenting with a decent $50 starter pot to begin to learn a little about how clay changes tea.

5171038768_14cfa1630a.jpg

I have come to agree that truly great clay, fired well, will perform well with any tea regardless of color.


This #1 zini clay from Wuxing Shan Fang will brew everything from the darkest of puerh to floral and fragrant gaoshan. Mostly used for puerh of all ages. Comparing it side by side with porcelain brewing fresh, floral young sheng, the clay steals none of the aroma, and actually seems to focus and harmonize the fragrance with the taste.

Tea-masters blog recently had a post discussing brewing green tea in old zini.

Modern clays could still make good pots in their own right, even if simply for the enjoyment of using a pot over a gaiwan and added heat retention.

[BW85]

[quote="kyarazen"

the monotonic decrease with the shape of the pot is what that makes a pot unique. the clay benefits and properties, are much more short lived than the effects of the shape and thermal properties

Is cleaning out the inside of your pots something you plan on doing throughout the years? To maintain the catalytictic nature of the clay?

nope!! the shape and therm properties is important, but the external patina even more! i derive great pleasure in nurturing pots and seeing the patina develop. red clay, dark clay, light clay have different heat capacities and radiatively lose heat differently.. this physical property doesnt change with time.[/quote]

Cool, was just curious. I too would not want to remove any treasured patina from years of loving my pots!

[kyarazen]

This #1 zini clay from Wuxing Shan Fang will brew everything from the darkest of puerh to floral and fragrant gaoshan. Mostly used for puerh of all ages. Comparing it side by side with porcelain brewing fresh, floral young sheng, the clay steals none of the aroma, and actually seems to focus and harmonize the fragrance with the taste.

Tea-masters blog recently had a post discussing brewing green tea in old zini.

Modern clays could still make good pots in their own right, even if simply for the enjoyment of using a pot over a gaiwan and added heat retention.

lovely! if i run out of pots to buy i'll pick a piece up

[xiaobai]

I own three pots from EoT (none made of that expensive zini #1 clay though) and never found them to perform exceptionally well with yancha. Indeed, one of them, a PanHu made of Tian Qing Ni clay, especially recommended in the EoT website for yancha is the best performer, but it still steals much of the fragrance from most types of yancha that I throw in (especially SX). Other zini pots that I have tried from late 1980s F1 also do not perform particularly well, even for a flat shape. But perhaps they should become more seasoned to work better.

Concerning the red/brown/other clay debate, we just carried out a comparison of the PanHu side-by-side with red clay (niangaotu, a mix of zisha and some red clay) F1 1980s shui ping and the latter came out as a clear winner, making the yancha (a relatively cheap DHP) mellower and more fragrant in general.

However, I also would agree with wert that all those clay denominations have by now lost much of their meaning. They probably meant something when all the clay came from one single source, like F1 or F2, and the mixing, firing techniques, etc. were pretty standardized as corresponds to a factory production of a certain period.

Concerning color and shape and heat retention. In theory, color has indeed much to do with how much heat is radiated to the environment (black body radiation). However, to be frank, my bet is that radiation losses kick in at bit later in time than conductive heat loss. And the latter is larger from the bottom of the pot, which is in contact with the tea boat or whatever surface or teaware element you place the pot on.

In addition, if, as Kyarazen seems to suggest, the radiative heat loss was dominant, then everything would be determined by the total surface area of the pot. But, as a matter of fact, this a non-monotonic function of the base radius for constant volume (assume the shape of a cylinder to simplify things). This means that, for instance, a 100 ml pot can have two possible shapes with the same total surface area, one of them tall and the other flat. However, this contradicts most peoples' experience that flatter pots do indeed cool at a much faster rate. This is because the heat loss happens conductively through the bottom, and it is therefore determined by the contact surface area with the (solid) material that supports the pot.

By the way: FYI, The comparison described on Stephane's tea masters website was not with zini, but old zisha. I happen to know first hand.

[kyarazen]

whether it conducts through the base still depends on the material you sit your pot on. a flatter pot will still have a larger surface area than a round one for the same volume and not equal. there is no contradiction is there? i had always observed that flatter pots cool faster than tall pots.

would it be possible to have a 100ml pot of fixed surface area on the same volume in 2 shapes of sphere vs flat ellipsoid? you can mathematically derive it, just to give you some parameters you can consider the following semi axis of
a = 10, b = 10, c= 10, that would give you a perfect round volume at approx 418x, surface area is 1200+, versus a flat spheroid of a = 14.1, b = 5, c = 14.1, volume approx 416x, surface area 1500+.

even in F1, clays were changing all the years. maybe the clay expert can share with us how it evolved from the early 50s to the 90s and which era did which clay appear and disappear

I own three pots from EoT (none made of that expensive zini #1 clay though) and never found them to perform exceptionally well with yancha. Indeed, one of them, a PanHu made of Tian Qing Ni clay, especially recommended in the EoT website for yancha is the best performer, but it still steals much of the fragrance from most types of yancha that I throw in (especially SX). Other zini pots that I have tried from late 1980s F1 also do not perform particularly well, even for a flat shape. But perhaps they should become more seasoned to work better.

Concerning the red/brown/other clay debate, we just carried out a comparison of the PanHu side-by-side with red clay (niangaotu, a mix of zisha and some red clay) F1 1980s shui ping and the latter came out as a clear winner, making the yancha (a relatively cheap DHP) mellower and more fragrant in general.

However, I also would agree with wert that all those clay denominations have by now lost much of their meaning. They probably meant something when all the clay came from one single source, like F1 or F2, and the mixing, firing techniques, etc. were pretty standardized as corresponds to a factory production of a certain period.

Concerning color and shape and heat retention. In theory, color has indeed much to do with how much heat is radiated to the environment (black body radiation). However, to be frank, my bet is that radiation losses kick in at bit later in time than conductive heat loss. And the latter is larger from the bottom of the pot, which is in contact with the tea boat or whatever surface or teaware element you place the pot on.

In addition, if, as Kyarazen seems to suggest, the radiative heat loss was dominant, then everything would be determined by the total surface area of the pot. But, as a matter of fact, this a non-monotonic function of the base radius for constant volume (assume the shape of a cylinder to simplify things). This means that, for instance, a 100 ml pot can have two possible shapes with the same total surface area, one of them tall and the other flat. However, this contradicts most peoples' experience that flatter pots do indeed cool at a much faster rate. This is because the heat loss happens conductively through the bottom, and it is therefore determined by the contact surface area with the (solid) material that supports the pot.

By the way: FYI, The comparison described on Stephane's tea masters website was not with zini, but old zisha. I happen to know first hand.

[steanze]

it is a fine balance, if you understand the properties of a pot and complement it with appropriate brewing procedures, you can use that single pot for any tea and achieve good results. I'm not denying that clay does have effects on the brew, since i've been using japanese clays that are more leachy than oxidation fired yixings. but over time if you have really nice clay, the internal surface changes over usage, the pores and crevices get stained and filled, this activity decreases. if a pot were to be relied on the leaching properties, then its property is not long lasting. (this leachy thing can be augmented by either using a better kettle, or using different types of water with different mineral contents to make up for it). very porous or not well fired pots can be rather absorptive and can ruin a tea's aromatics, the patina is hard to raise, but if you use it patiently for incredibly long amounts of time, they will stop being robbers as the interior surface gets blocked by tea stains or water residues.

the monotonic decrease with the shape of the pot is what that makes a pot unique. the clay benefits and properties, are much more short lived than the effects of the shape and thermal properties.

I think clay has two effects on the brew: one due to leaching and one to absorption. I think the leaching effect can make the taste of the water more mineral, the absorption effect contributes to producing a smoother brew and reduce bitterness, but usually removes some of the aromatics. Do you think that smoother brew and reduction in the aromatics also result from leaching? I'm not a chemist/material scientist so mine are just guesses. The inside of the pot does change with use, but one question is how long it takes for that to significantly alter the "smoothing" properties of the clay. I have a dcq pot (not low fired) that I've been using for over 6 years with pu erh and I find it still smooths the taste of the tea It has a nice patina and some tea coating inside but it does not cover entirely the inside of the pot and it is mostly concentrated in the bottom. But I do use other pots too so it doesn't see daily use, it used to earlier when I had fewer pots but now it's more like once or twice a week.
To sum up I would agree that the thermal properties are longer lived, but still it would be nice to find out how long it takes until a pot gets so stained that its absorptive properties are largely affected (possibly a very long time) and it seems that that would be an important factor to decide how important they are in the selection of a pot

[steanze]

I'm probably just confusing terms, don't mind me! I think TJ and Steanze are right, that TGY pot is very fine sand.

I think your terms were ok, I am not sure there's a standard terminology in English for this so I just resorted to examples

[AT333]

i derive great pleasure in nurturing pots and seeing the patina develop.

Those super monk shine pots you featured in your blog are really amazing and jaw dropping.

[BW85]

I own three pots from EoT (none made of that expensive zini #1 clay though) and never found them to perform exceptionally well with yancha.

I use one of the EoT haunglongshan pots for yancha regularly, it's actually my preferred yancha pot over several others I use occasionally. But it could be due to my personal preference; when drinking yancha I don't care that much about the aroma, its all about mouth feel and body to me. Aside from the wonderful empty cup aroma!

By the way: FYI, The comparison described on Stephane's tea masters website was not with zini, but old zisha. I happen to know first hand.

Zini, zisha... Just words.

[steanze]

I own three pots from EoT (none made of that expensive zini #1 clay though) and never found them to perform exceptionally well with yancha.

I use one of the EoT haunglongshan pots for yancha regularly, it's actually my preferred yancha pot over several others I use occasionally. But it could be due to my personal preference; when drinking yancha I don't care that much about the aroma, its all about mouth feel and body to me. Aside from the wonderful empty cup aroma!

By the way: FYI, The comparison described on Stephane's tea masters website was not with zini, but old zisha. I happen to know first hand.

Zini, zisha... Just words.

Yes, I also think personal preference plays an important role - I tried yancha in various zini pots and I still prefer it in hongni/zhuni (to the point that I prefer it in lower quality hongni clay (not too low though ) than in higher quality zini), but I know several people who like zini for yancha, including also people who have more experience with tea than myself.
By the way I think this thread is really nice - I feel I am learning a lot from everyone else's experiences and we are managing to discuss different views in a very open and friendly environment

[wyardley]

Agree with not discounting a gaiwan.

I have tried lots of pots of different types / ages for yancha, and still prefer a gaiwan for many of them (and it's not only light-fired ones that often benefit from this treatment).

To me, it's the quality of the tea vs. the style that matters - a higher quality tea may benefit from extra heat retention of a yixing pot vs. a thin-walled gaiwan, but for many teas, to my taste, the results from using the gaiwan are often better. YMMV, obviously. Pour speed is probably also partially a factor (and may be a big factor in the differences between pots).

Pots do have their own mystique and there's definitely a joy in watching them develop.

[xiaobai]

whether it conducts through the base still depends on the material you sit your pot on. a flatter pot will still have a larger surface area than a round one for the same volume and not equal. there is no contradiction is there? i had always observed that flatter pots cool faster than tall pots.

would it be possible to have a 100ml pot of fixed surface area on the same volume in 2 shapes of sphere vs flat ellipsoid? you can mathematically derive it, just to give you some parameters you can consider the following semi axis of a = 10, b = 10, c= 10, that would give you a perfect round volume at approx 418x, surface area is 1200+, versus a flat spheroid of a = 14.1, b = 5, c = 14.1, volume approx 416x, surface area 1500+.

even in F1, clays were changing all the years. maybe the clay expert can share with us how it evolved from the early 50s to the 90s and which era did which clay appear and disappear

'

I think everybody agrees (and the data in your blog shows it) that flatter pots cool faster.

To make a fair comparison we must compare pots of different shapes but equal volume. The reason being that, when hot water is poured in, the heat that is provided is (roughly) proportional to the mass of water held by the pot, that is, the pot's volume in ml = cm^3 = grams.

A spherical or ellipsoidal shape have rather ill defined contact area with the surfaces they sit on (mathematically it is just a point = zero area). I think a better model for a pot is a cylinder of height H and basal radius R.

The volume of the cylinder (pot) is V = pi R^2 H

The surface area of the cylinder is S = 2 pi R (R + H)

If we use the first equation to solve for H, and substitutes in the second
equation, we get the following law for the surface area as a function of the
basal radius:

S(R) = 2 pi R^2 + 2V/R

This a non-monotonic function of the basal radius, R. In particular, it has
a minimum for H = 2R, at which point the surface area equals 6 pi R^2, that is, one and a half times the surface area of a sphere of radius equal to R.

Below is a plot of S(R) normalized to the minimum of the surface area as a function of R divided by the basal radius at the minimum. It shows the non-monotonic behavior mentioned earlier.

The above considerations illustrate the rather simple fact that we can have two different cylindrical-shape pots of the same volume, one flat and one tall.

It then naturally follows that, if the heat loss is radiative and therefore proportional to the total surface area of the pot, then one can have two pots of the same volume but different shape (tall and flat) that will cool at (roughly) the same rate.

IMO, the only way out of this contradiction with the experience is to notice that a large fraction of the initial cooling happens conductively through the base of the pot by releasing heat to the surface it sits on. Since a flat pot has larger contact area with the latter than a tall pot, it should cool faster.

It is also natural to expect that heat conduction occurs dominantly through the bottom of the pot because it is in contact with a solid surface which can conduct heat much more efficiently than the air surrounding the pot. For the surface in contact with the air, the dominant mechanism is radiative, as pointed out above, but this should dissipate less heat for the relatively small temperature differences between the pot and the surrounding air.