Yixing

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Baisao
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Sat Apr 02, 2022 1:04 pm

LeoFox wrote:
Fri Apr 01, 2022 10:49 am
Baisao wrote:
Sun Mar 27, 2022 10:20 pm
So-called shrinking lines on two pots I believe are 1990s. I enjoy how they look skin-like in person. They are generally more visible in person than in photos.
Image
Image
https://digitalfire.com/glossary/firing+shrinkage
As kiln temperature increases bodies densify (particles pack closer and closer). As temperature continues to rise, some of the particles begin to melt and form a glass between the others that pulls them even closer. Some of the particles shrink themselves, kaolin is an example (in the raw state particles are often loosely packed in layers, these pull together at temperature rises). These factors result in shrinkage of ware during firing.

Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification
These shrinkages are not a product of temperature, but of the amount of flux present in a body to develop particle-bonding glass during firing. Fluxes are available at all temperatures, at higher temperatures feldspar is the most common, at the lowest temperatures frit is used.
Based on this, large, obvious wrinkling doesn't seem to make sense - why would it happen if it means the particles in the clay are being held closer by vitrification of other particles. The overall clay body should be relatively homogenous at this point. I wonder if these obviously wrinkled pots are from using some slip with different shrinkage properties- or some coloring agents on the surface that changes vitrification temperature just near the surface. By obvious wrinkles - something like this

https://yinchenstudio.com/collections/z ... apot-140ml
These have no apparent slip but I have seen other that do have slip over the clay yet the wrinkles are negligible. Maybe it has to be a thick slip?
Andrew S
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Sat Apr 02, 2022 6:11 pm

Here's another old pot that (so far as I can tell) reinforces Bok's point that old pots exhibit a kind of 'warping' rather than shrinkage (though it is hard to photograph).

I'm obviously not an expert in the slightest, but I'm sure that there is a vast difference between the effect of old dragon kilns and the effect of modern kilns (and processing, etc).

@Bok: by the way, nice to see that pot in action... Are you worried that it'll develop more cracks from use because of the special clay, or is that only really a problem if it is used carelessly?

Andrew
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Bok
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Sat Apr 02, 2022 7:18 pm

@Andrew S I simply got distracted by other pots, that’s why it got neglected.

I have a rather fatalistic view - if they break they break and that’s that. Once you pass a certain threshold of broken and damaged pots, you get rather relaxed about this…

But I guess I’ll find out how bad this clay really is in that regard and what happens to heavily stapled pots over time. So far none of my other stapled pots have become worse over time. Actually, even among the pots that have hairlines without adding staples, has any of them gotten worse. Fingers crossed.

Take the one attached, a lot of staples on some really bad cracks, very heavy use by me - so far no deterioration.
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Youzi
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Sun Apr 03, 2022 5:15 am

LeoFox wrote:
Fri Apr 01, 2022 10:49 am
Baisao wrote:
Sun Mar 27, 2022 10:20 pm
So-called shrinking lines on two pots I believe are 1990s. I enjoy how they look skin-like in person. They are generally more visible in person than in photos.
Image
Image
https://digitalfire.com/glossary/firing+shrinkage
As kiln temperature increases bodies densify (particles pack closer and closer). As temperature continues to rise, some of the particles begin to melt and form a glass between the others that pulls them even closer. Some of the particles shrink themselves, kaolin is an example (in the raw state particles are often loosely packed in layers, these pull together at temperature rises). These factors result in shrinkage of ware during firing.

Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification
These shrinkages are not a product of temperature, but of the amount of flux present in a body to develop particle-bonding glass during firing. Fluxes are available at all temperatures, at higher temperatures feldspar is the most common, at the lowest temperatures frit is used.
Based on this, large, obvious wrinkling doesn't seem to make sense - why would it happen if it means the particles in the clay are being held closer by vitrification of other particles. The overall clay body should be relatively homogenous at this point. I wonder if these obviously wrinkled pots are from using some slip with different shrinkage properties- or some coloring agents on the surface that changes vitrification temperature just near the surface. By obvious wrinkles - something like this

https://yinchenstudio.com/collections/z ... apot-140ml
Most of the times it's the "definition" setting on these studio photos. They aren't really that apparent as on those pictures.

In cheap locomotive pots they use toilet paper to fake shrink lines.

And I also heard that they make the shrink lines more apparent by purposefully fluctuating the temperature at the end of the firing stage of pots.
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LeoFox
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Sun Apr 03, 2022 5:37 am

Youzi wrote:
Sun Apr 03, 2022 5:15 am

In cheap locomotive pots they use toilet paper to fake shrink lines.

And I also heard that they make the shrink lines more apparent by purposefully fluctuating the temperature at the end of the firing stage of pots.
Wow!
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Youzi
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Sun Apr 03, 2022 7:48 am

LeoFox wrote:
Sun Apr 03, 2022 5:37 am
Youzi wrote:
Sun Apr 03, 2022 5:15 am

In cheap locomotive pots they use toilet paper to fake shrink lines.

And I also heard that they make the shrink lines more apparent by purposefully fluctuating the temperature at the end of the firing stage of pots.
Wow!
In case it wasn't apparent. The toilet paper and the special firing are two different techniques used for two totally different price ranges and class of teapots.
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LeoFox
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Sun Apr 03, 2022 8:07 am

Youzi wrote:
Sun Apr 03, 2022 7:48 am
LeoFox wrote:
Sun Apr 03, 2022 5:37 am
Youzi wrote:
Sun Apr 03, 2022 5:15 am

In cheap locomotive pots they use toilet paper to fake shrink lines.

And I also heard that they make the shrink lines more apparent by purposefully fluctuating the temperature at the end of the firing stage of pots.
Wow!
In case it wasn't apparent. The toilet paper and the special firing are two different techniques used for two totally different price ranges and class of teapots.
This is amazing!! :lol:
.m.
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Location: Prague

Sun Apr 03, 2022 2:00 pm

LeoFox wrote:
Fri Apr 01, 2022 10:49 am
Baisao wrote:
Sun Mar 27, 2022 10:20 pm
So-called shrinking lines on two pots I believe are 1990s. I enjoy how they look skin-like in person. They are generally more visible in person than in photos.
Image
Image
https://digitalfire.com/glossary/firing+shrinkage
As kiln temperature increases bodies densify (particles pack closer and closer). As temperature continues to rise, some of the particles begin to melt and form a glass between the others that pulls them even closer. Some of the particles shrink themselves, kaolin is an example (in the raw state particles are often loosely packed in layers, these pull together at temperature rises). These factors result in shrinkage of ware during firing.

Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification
These shrinkages are not a product of temperature, but of the amount of flux present in a body to develop particle-bonding glass during firing. Fluxes are available at all temperatures, at higher temperatures feldspar is the most common, at the lowest temperatures frit is used.
Based on this, large, obvious wrinkling doesn't seem to make sense - why would it happen if it means the particles in the clay are being held closer by vitrification of other particles. The overall clay body should be relatively homogenous at this point. I wonder if these obviously wrinkled pots are from using some slip with different shrinkage properties- or some coloring agents on the surface that changes vitrification temperature just near the surface. By obvious wrinkles - something like this

https://yinchenstudio.com/collections/z ... apot-140ml
I don't believe the shrink lines are caused simply by firing - they are already in the clay and are exposed by firing, the same way the joint lines are exposed. They are the places where the inner structure of the clay is different because of the way it was worked. On the teapot by Yinchen, you can see how those lines are where the body was shrinked during the raw clay forming by tapping. They are not on the lid, which is formed by stretching, and they are less prominent around the outer diameter of the pot. Btw. there's something seriously wrong with the shine of the pot. The higher shrinkage rate of zhuni does plays important role: it exposes better the non-homogeneity of the clay. The mesh probably plays a role too, and perhaps the clay composition and the firing as well. But the forming process is crucial, even if it is designed to exaggerate those traits. Or they are artificially faked, that too is an option.
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Baisao
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Sun Apr 03, 2022 2:55 pm

That Yinchen teapot is to lao zhuni as pineapple pizza is to pizza margherita. It shines like an oiled up body builder and has all of grannie’s wrinkles.

@.m., I get your point but would like to point out that this is only seen on modern zhuni. What in the clay might cause this? Too much flux? A slip? It’s obviously an engineered clay and I’d avoid using pots with such exaggerated shine and wrinkles.
.m.
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Sun Apr 03, 2022 3:07 pm

In old pots you can often see joint lines (but usually not this pronounced) and deformations of the body surface where it was tapped. This kind of fine net of shrinkage lines, i'm not sure.... if it existed then it is rare. But the clay and processing changes, maybe that could be a factor.
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LeoFox
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Sun Apr 03, 2022 5:42 pm

:lol: :lol:

https://www.teachat.com/viewtopic.php?t=15168
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alejandro2high
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Location: Dallas–Fort Worth, TX

Sun Apr 10, 2022 8:53 am

LeoFox wrote:
Fri Apr 01, 2022 10:49 am
Baisao wrote:
Sun Mar 27, 2022 10:20 pm
So-called shrinking lines on two pots I believe are 1990s. I enjoy how they look skin-like in person. They are generally more visible in person than in photos.
Image
Image
https://digitalfire.com/glossary/firing+shrinkage
As kiln temperature increases bodies densify (particles pack closer and closer). As temperature continues to rise, some of the particles begin to melt and form a glass between the others that pulls them even closer. Some of the particles shrink themselves, kaolin is an example (in the raw state particles are often loosely packed in layers, these pull together at temperature rises). These factors result in shrinkage of ware during firing.

Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification
These shrinkages are not a product of temperature, but of the amount of flux present in a body to develop particle-bonding glass during firing. Fluxes are available at all temperatures, at higher temperatures feldspar is the most common, at the lowest temperatures frit is used.
Based on this, large, obvious wrinkling doesn't seem to make sense - why would it happen if it means the particles in the clay are being held closer by vitrification of other particles. The overall clay body should be relatively homogenous at this point. I wonder if these obviously wrinkled pots are from using some slip with different shrinkage properties- or some coloring agents on the surface that changes vitrification temperature just near the surface. By obvious wrinkles - something like this

https://yinchenstudio.com/collections/z ... apot-140ml
I'm pretty sure that Yixing does not vitrify which is the whole point since that's what allows the clay to have an effect on the water. Vitrification makes clay bodies impervious to water which is not the case with Yixing; Yixing is porous.
Last edited by alejandro2high on Sun Apr 10, 2022 3:03 pm, edited 1 time in total.
alejandro2high
Posts: 69
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Location: Dallas–Fort Worth, TX

Sun Apr 10, 2022 8:55 am

.m. wrote:
Sun Apr 03, 2022 2:00 pm
LeoFox wrote:
Fri Apr 01, 2022 10:49 am
Baisao wrote:
Sun Mar 27, 2022 10:20 pm
So-called shrinking lines on two pots I believe are 1990s. I enjoy how they look skin-like in person. They are generally more visible in person than in photos.
Image
Image
https://digitalfire.com/glossary/firing+shrinkage
As kiln temperature increases bodies densify (particles pack closer and closer). As temperature continues to rise, some of the particles begin to melt and form a glass between the others that pulls them even closer. Some of the particles shrink themselves, kaolin is an example (in the raw state particles are often loosely packed in layers, these pull together at temperature rises). These factors result in shrinkage of ware during firing.

Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification
These shrinkages are not a product of temperature, but of the amount of flux present in a body to develop particle-bonding glass during firing. Fluxes are available at all temperatures, at higher temperatures feldspar is the most common, at the lowest temperatures frit is used.
Based on this, large, obvious wrinkling doesn't seem to make sense - why would it happen if it means the particles in the clay are being held closer by vitrification of other particles. The overall clay body should be relatively homogenous at this point. I wonder if these obviously wrinkled pots are from using some slip with different shrinkage properties- or some coloring agents on the surface that changes vitrification temperature just near the surface. By obvious wrinkles - something like this

https://yinchenstudio.com/collections/z ... apot-140ml
I don't believe the shrink lines are caused simply by firing - they are already in the clay and are exposed by firing, the same way the joint lines are exposed. They are the places where the inner structure of the clay is different because of the way it was worked. On the teapot by Yinchen, you can see how those lines are where the body was shrinked during the raw clay forming by tapping. They are not on the lid, which is formed by stretching, and they are less prominent around the outer diameter of the pot. Btw. there's something seriously wrong with the shine of the pot. The higher shrinkage rate of zhuni does plays important role: it exposes better the non-homogeneity of the clay. The mesh probably plays a role too, and perhaps the clay composition and the firing as well. But the forming process is crucial, even if it is designed to exaggerate those traits. Or they are artificially faked, that too is an option.
The shrink lines and shine are due to the clay characteristics. There's a reason that pot is the most expensive on Yinchen's site. The image is also edited which adds to the shine.

I disagree that shrink lines are caused by how the clay is worked since shrink lines are only found on pots made from certain clays.
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Baisao
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Sun Apr 10, 2022 6:56 pm

alejandro2high wrote:
Sun Apr 10, 2022 8:53 am
I'm pretty sure that Yixing does not vitrify which is the whole point since that's what allows the clay to have an effect on the water. Vitrification makes clay bodies impervious to water which is not the case with Yixing; Yixing is porous.
This is demonstrably false.
alejandro2high
Posts: 69
Joined: Tue Dec 17, 2019 1:51 pm
Location: Dallas–Fort Worth, TX

Sun Apr 10, 2022 7:29 pm

Baisao wrote:
Sun Apr 10, 2022 6:56 pm
alejandro2high wrote:
Sun Apr 10, 2022 8:53 am
I'm pretty sure that Yixing does not vitrify which is the whole point since that's what allows the clay to have an effect on the water. Vitrification makes clay bodies impervious to water which is not the case with Yixing; Yixing is porous.
This is demonstrably false.
Please link something that speaks to Yixing being vitrified.

Edit: Vitrification is the clay pretty much becoming glass. Yixing does not do this. Or am I completely off base?
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