I'm trying to improve my eye for identifying and evaluating yixing teapots, and I'd love to get more info regarding the characteristics of slipcased teapots. I know there is some information scattered throughout the board, but it'd be helpful to have a reference guide with photos in one topic.
Anybody want to share?
Re: How to tell if an yixing teapot is slipcast?
One thing I have to say about this topic is that almost all Chinese teapots, including the expensive ones, today are made from moulds.
About signs of slip casting...I wish I knew. Let the experts answer that one.
On the other hand, I highly recommend this reading:
The Way of Tea, The Sublime Art of Oriental Tea Drinking by Lam Kam Chuen.
Cheers.
About signs of slip casting...I wish I knew. Let the experts answer that one.
On the other hand, I highly recommend this reading:
The Way of Tea, The Sublime Art of Oriental Tea Drinking by Lam Kam Chuen.
Cheers.
Last edited by bagua7 on Oct 14th, '10, 05:59, edited 1 time in total.
Re: How to tell if an yixing teapot is slipcast?
Slipcast Yixing is made from liquid, Yixing clay is from ore, a stone. Wheel-used Yixing is halfway between, in terms of clay composition.
So even if I never bought one, I can safely guess it is hardly porous. And from experience, they are deformed in shape and cheaper than wheel-used Yixings.
Although today's many Yixing teapots come using moulds, traditional mould-using still requires hands and skills much, so they call it Ban Shou Gong (half hand-made), so it's still of artisan's level which beginners like us will hardly follow after.
So even if I never bought one, I can safely guess it is hardly porous. And from experience, they are deformed in shape and cheaper than wheel-used Yixings.
Although today's many Yixing teapots come using moulds, traditional mould-using still requires hands and skills much, so they call it Ban Shou Gong (half hand-made), so it's still of artisan's level which beginners like us will hardly follow after.
Re: How to tell if an yixing teapot is slipcast?
Since slipcast teapot is made from liquid clay, it will have an extremely fine smooth appearance. There will be hardly any signs (marks) that it was worked by hands.
To tell a teapot is a antique or not, one must look the at granularity of the clay. Before 1950's the clay are processed by hands without machinery, so it was coarse and unrefined, after that the clay was highly processed and refined, and so the teapots have very smooth appearance.
Unrefined clay are harder to work on and so it takes real skills to produce a masterpiece of art.
To tell a teapot is a antique or not, one must look the at granularity of the clay. Before 1950's the clay are processed by hands without machinery, so it was coarse and unrefined, after that the clay was highly processed and refined, and so the teapots have very smooth appearance.
Unrefined clay are harder to work on and so it takes real skills to produce a masterpiece of art.
Re: How to tell if an yixing teapot is slipcast?
I always though "slipcast" referred to a teapot that was coated or painted on the outside with makeup clay. So a pot that has makeup clay on the outside isn't necessarily slipcast? Learn something new everyday... http://en.wikipedia.org/wiki/Slipcasting
O.K. Now I'm very interested in this topic. Proceed experts!
O.K. Now I'm very interested in this topic. Proceed experts!
Oct 14th, '10, 11:39
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Re: How to tell if an yixing teapot is slipcast?
My understanding of slip cast is same as chrl42's. A better made slip cast can be better than a poorly made real yixing though. I think the slip cast always has smoother texture than yixing and is almost glassy. But I heard there is some technique to do slip cast with more sandy materials and don't know if it's true and if some people even bother to do it.
A slip cast teapot almost always has an obvious single line across the exact middle line of the spout all the way to the bottom of the teapot, similar to the line across the bottom of a glass mug. Better quality slip casts are made with better shape moulds so the line can be thin, but still visible. Some maker spend extra work to smooth away the line but there is still some hint of it.
A slip cast teapot almost always has an obvious single line across the exact middle line of the spout all the way to the bottom of the teapot, similar to the line across the bottom of a glass mug. Better quality slip casts are made with better shape moulds so the line can be thin, but still visible. Some maker spend extra work to smooth away the line but there is still some hint of it.
Re: How to tell if an yixing teapot is slipcast?
During late-70's at Factory-1, there was a slip-casted teapot, clay called Nian Gao Tu (cake-clay). Color between red and brown, tenderness exceeds any other Yixing clay.
But Nian Gao Tu then disappeared from market, because it was harder to make than half hand-made pots...this clay pot is on wish-list of many Taiwanese collectors nowdays..
But Nian Gao Tu then disappeared from market, because it was harder to make than half hand-made pots...this clay pot is on wish-list of many Taiwanese collectors nowdays..
Re: How to tell if an yixing teapot is slipcast?
Naturally I had to check my one yixing teapot - no trace at all of a line. There is a year carved at the base of the spout in very small type, so made in a mold but not slip-cast.gingkoseto wrote:A slip cast teapot almost always has an obvious single line across the exact middle line of the spout all the way to the bottom of the teapot, similar to the line across the bottom of a glass mug. Better quality slip casts are made with better shape moulds so the line can be thin, but still visible. Some maker spend extra work to smooth away the line but there is still some hint of it.
Oct 15th, '10, 11:01
Posts: 1796
Joined: Sep 15th, '09, 16:11
Location: Wilton, New Hampshire USA
Re: How to tell if an yixing teapot is slipcast?
Putting a clay slip on a piece as a surface decoration or body disguising technique and the practice of slip casting could be a bit confusing to the non-ceramist.
Applying a smooth and possibly different colored clay "slip" on the outside of a clay form made out of a possibly less refined clay body is a very old technique. It allows one to make the visual characteristics of the surface resemble a different material. So for example, the use of a white kaolin based slip on a coarse iron bearing stoneware was used to make that clay look more "refined" and pure. Eventually the casual application of this kind of white slip with a brush in quickly produced wares began to be appreciated for it's own decorative qualities... and you get to some of the prized hakeme type chawan from Korea and Japan.
Slip casting (forming a 3 dimensional piece out of a liquid clay slip) is one of the many means that have been developed to allow the fast reproduction of ceramic forms by lower skilled laborers. It is not a totally unskilled process....... GOOD mold work requires a lot of specific skills. It is just far less in the way of training than a well rounded potter would have. I could train most anyone on this forum to produce and clean up really decent casts out of a specific mold form in about 2 weeks time.
Slip casting involves mixing up a clay body that usually, but not always, does not have LARGE more granular materials in it with water, and then pouring this suspension into a porous mold of the form to be created. The slip is usually a specialized one compared to decorating slip, and it is usually chemically adjusted so that you get good "rheology" (flow charasterics) with a minimal amount of water. This is called a deflocculated slip.
The mold, being porous, "sucks" water into itself. In the process this causes a layer ofthe clay body material to be deposited along the interior face of the mold. The amount of time that the liquid slip is left inside the mold before pouring the excess out determines the thickness of the clay wall that you get. The dampness of the mold itself from repeated castings affects this timing....making is longer and longer as the mold gets used. Eventually the molds have to be fully dired out. When the clay walls are at the correct thickness, the excess liquid slip is poured out and the walls are left to stiffen to a state that resembles hard cheeze.
Then the mold is opened and the damp form is very carefully removed. These molds can be single piece for stuff like cups or bowls, up to many multiple pieces for complex forms.
At this point the mold lines and the "sprue" (just like in metal casting) are typically cleaned off. This is actually a rather difficult process to do really well. Cheap stuff often shows a poor cleanup of these mold lines and can be a give away of casting. (But not always.)
The cheeze hard piece can then be manipulated further. This is the time that other slip cast pieces, like handles, spouts, and so on, can be added to the piece. The additions are added to the basic form by creating a little rough texture at the places they are to be joined, and then using a thin layer of the clay body slip to act as a "joiner" or "glue" between the two parts. The join is smoothed over and carefully cleaned up.
The pieces are then left to dry and are fired just like work fabricated in most other ways.
Slip casting can also use what is known as solid cast molds. It does not determine the thickness of the walls by the time the slip is in the generally hollow mold interior...... but the negative space in the mold is the EXACT thickenss and contour of both surfaces of the piece. More like lost wax metal casting. This is a specialized application, and requires a good master designer, technical mold person, and good equipment.
The pre-cursor to slip casting is something called press moulding. That involves placing slabs of plastic clay into a mold that is very similar to a slip casting mold. If the mold is sectional (more than one piece), it is designed so that the potter can join the different wet slabs from the inside by hand. This technique was and is VERY common in Japanese workshops for certain forms. I use some of this for certain handbuilt forms, as do many ceramic artist I know. For an example of this, look at HAMADA Shoji's rectalinear bottle forms.
Press molding would fit many of the more geometric Yixing teapot forms well.
There are other industrialized replication techniques that also use molds such as jiggering/jollying, pressure casting, hydraulic pressing and so on. What can be done across the spectrum of ceramics is pretty amazing.
I can tell you that I have first hand seen mold produced work being produced in asia that is pretty much indistinguishable by all persons but a really knowledgable potter from totally hand made work. Right down to "wonky" asymetrical forms, "throwing" lines, potter's fingerprints, imperfections, and so on. Many of those really cheap chawan are produced this way.
best,
...........john
Applying a smooth and possibly different colored clay "slip" on the outside of a clay form made out of a possibly less refined clay body is a very old technique. It allows one to make the visual characteristics of the surface resemble a different material. So for example, the use of a white kaolin based slip on a coarse iron bearing stoneware was used to make that clay look more "refined" and pure. Eventually the casual application of this kind of white slip with a brush in quickly produced wares began to be appreciated for it's own decorative qualities... and you get to some of the prized hakeme type chawan from Korea and Japan.
Slip casting (forming a 3 dimensional piece out of a liquid clay slip) is one of the many means that have been developed to allow the fast reproduction of ceramic forms by lower skilled laborers. It is not a totally unskilled process....... GOOD mold work requires a lot of specific skills. It is just far less in the way of training than a well rounded potter would have. I could train most anyone on this forum to produce and clean up really decent casts out of a specific mold form in about 2 weeks time.
Slip casting involves mixing up a clay body that usually, but not always, does not have LARGE more granular materials in it with water, and then pouring this suspension into a porous mold of the form to be created. The slip is usually a specialized one compared to decorating slip, and it is usually chemically adjusted so that you get good "rheology" (flow charasterics) with a minimal amount of water. This is called a deflocculated slip.
The mold, being porous, "sucks" water into itself. In the process this causes a layer ofthe clay body material to be deposited along the interior face of the mold. The amount of time that the liquid slip is left inside the mold before pouring the excess out determines the thickness of the clay wall that you get. The dampness of the mold itself from repeated castings affects this timing....making is longer and longer as the mold gets used. Eventually the molds have to be fully dired out. When the clay walls are at the correct thickness, the excess liquid slip is poured out and the walls are left to stiffen to a state that resembles hard cheeze.
Then the mold is opened and the damp form is very carefully removed. These molds can be single piece for stuff like cups or bowls, up to many multiple pieces for complex forms.
At this point the mold lines and the "sprue" (just like in metal casting) are typically cleaned off. This is actually a rather difficult process to do really well. Cheap stuff often shows a poor cleanup of these mold lines and can be a give away of casting. (But not always.)
The cheeze hard piece can then be manipulated further. This is the time that other slip cast pieces, like handles, spouts, and so on, can be added to the piece. The additions are added to the basic form by creating a little rough texture at the places they are to be joined, and then using a thin layer of the clay body slip to act as a "joiner" or "glue" between the two parts. The join is smoothed over and carefully cleaned up.
The pieces are then left to dry and are fired just like work fabricated in most other ways.
Slip casting can also use what is known as solid cast molds. It does not determine the thickness of the walls by the time the slip is in the generally hollow mold interior...... but the negative space in the mold is the EXACT thickenss and contour of both surfaces of the piece. More like lost wax metal casting. This is a specialized application, and requires a good master designer, technical mold person, and good equipment.
The pre-cursor to slip casting is something called press moulding. That involves placing slabs of plastic clay into a mold that is very similar to a slip casting mold. If the mold is sectional (more than one piece), it is designed so that the potter can join the different wet slabs from the inside by hand. This technique was and is VERY common in Japanese workshops for certain forms. I use some of this for certain handbuilt forms, as do many ceramic artist I know. For an example of this, look at HAMADA Shoji's rectalinear bottle forms.
Press molding would fit many of the more geometric Yixing teapot forms well.
There are other industrialized replication techniques that also use molds such as jiggering/jollying, pressure casting, hydraulic pressing and so on. What can be done across the spectrum of ceramics is pretty amazing.
I can tell you that I have first hand seen mold produced work being produced in asia that is pretty much indistinguishable by all persons but a really knowledgable potter from totally hand made work. Right down to "wonky" asymetrical forms, "throwing" lines, potter's fingerprints, imperfections, and so on. Many of those really cheap chawan are produced this way.
best,
...........john
Re: How to tell if an yixing teapot is slipcast?
Wow. What a great bunch of info John. Thanks for taking the time to write and share all that!
Oct 16th, '10, 10:41
Posts: 1796
Joined: Sep 15th, '09, 16:11
Location: Wilton, New Hampshire USA
Re: How to tell if an yixing teapot is slipcast?
tingjunkie wrote:Wow. What a great bunch of info John. Thanks for taking the time to write and share all that!
Zensuji wrote:Love the John info. Always a good read.
You are both most welcome.
Another thought here on the subject of authenticity and use of slip casting and ware pricing and such that comes from a major ceramics discussion list I am involved in is the recent mention there by a potter returning from China that "....the minimum wage in Fuping central China to be about $75/month this year. The master potter at the factory was probably making $175/month. His family had been potters for 700 years,......."
best,
............john
Re: How to tell if an yixing teapot is slipcast?
I don't agree with you at all about that because I do really know teapots all by hand in my hometown,yixing. And my father is good at making all-by-hand teapot.mayayo wrote:One thing I have to say about this topic is that almost all Chinese teapots, including the expensive ones, today are made from moulds.
Re: How to tell if an yixing teapot is slipcast?
Thank you everyone for your input. John, once again you've dropped some serious science on me.
Re: How to tell if an yixing teapot is slipcast?
I unknow the “slip cast”meaning.IF you say "mould",i think i will know.
teapot have a another way ,but it's not called yixing zisha teapot. "grout molding " is also not zisha teapot. I say the mould is another way ,by half-hand .Zisha teapot have two ways,half-hand and full-hand. O f couse ,a lot of people make the fraud teapot.Clay teapot is including of the clay-huang long shan of ding shan,hand makeing way,fire and so on .Not only teapot made of the clay is called zi sha teapot.
teapot have a another way ,but it's not called yixing zisha teapot. "grout molding " is also not zisha teapot. I say the mould is another way ,by half-hand .Zisha teapot have two ways,half-hand and full-hand. O f couse ,a lot of people make the fraud teapot.Clay teapot is including of the clay-huang long shan of ding shan,hand makeing way,fire and so on .Not only teapot made of the clay is called zi sha teapot.