Firing of yixing and the hype/scam of woodfiring

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LeoFox
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Fri Mar 24, 2023 10:51 am

One of my friends showed me this interesting article about the types of firing for yixing pots

https://kknews.cc/collect/96zmepq.html

The article primarily argues that the so called wabi Sabi appearance of many "wood fired" yixing pots are not from wood firing but from reduction firing + addition of various salts.

There is also a part of the article that talks about the fuels used in Yixing during different periods, which is very interesting:
Yixing’s purple clay teapots were basically fired with pine branches in a dragon kiln before the 1970s. At the end of the 1950s, the tail of the dragon kiln was opened and heated with lump coal, and the flame was fired. A layer of clay prevents the flame from directly hitting the teapot, thus ensuring the cleanness and purity of the surface of the teapot. In the past, if there was a fire leak, or if it was accidentally burned to a reduced flame, some fire ignorance would appear. This kind of thing is a defective product and cannot be sold as a genuine product.

Since the end of the 1960s, Yixing Zisha pot kiln was transformed into Suidao kiln, and the original dragon kiln production was abandoned. Due to the energy saving of Suidao kiln, the firing cost of the original dragon kiln was reduced by more than 30%. Therefore, dozens of dragon kilns in Yixing Since then, it has been completely shut down. In the mid-1970s, the fuel was changed from coal burning to heavy oil (slag from refining gasoline), and the cost was further reduced. In the early 1990s, the Taiwanese produced a shuttle kiln (pumping kiln) using liquefied petroleum gas, which was quickly introduced to make purple sand pots, which quickly increased the finished product rate to 98%. In fact, in the 1970s, the Yixing government issued regulations to encourage In the decision document of using coal and heavy oil to burn ceramics, after entering the 1990s, the use of wood-burning pottery was completely prohibited, and it was stipulated in the form of legislation. Liquefied petroleum gas and pipeline natural gas, so far, coal-fired kilns in Yixing have disappeared for nearly 30 years.


Regarding the fake wood firing:

So, where did the so-called firewood come from? In fact, it’s not firewood at all, but a century-old scam. The so-called firewood is just to deceive people who don’t know how to do it. Let’s popularize ceramics here. Kiln firing knowledge. There are two kinds of kiln firing atmospheres for firing ceramics, oxidizing atmosphere and reducing atmosphere.

The oxidizing atmosphere is that the air pressure in the furnace is greater than the pressure outside the kiln, so that the atmosphere in the furnace is very clean, because the impurities and dust outside the kiln cannot enter the furnace, so the surface of the fired purple clay pot is very clean and smooth, and the surface texture of the purple clay pot is natural and beautiful. It is also the standard that people generally require and hope to achieve in the 600-year history of Zisha.

Reducing atmosphere (also called reducing flame) is to adjust the air pressure in the kiln to be lower than the air pressure outside the kiln, so that the air outside the kiln includes nitrogen, inert gas and dust impurities, and even some bad rays can enter the kiln. As a result, a high-temperature reduction reaction occurs in the kiln, and ash falls on the surface of the ceramic product. In order to make the surface of the product more expressive, some industrial salt will be added when the temperature is over 1,000 degrees to liquefy the salt. The mist adheres to the surface of the product and absorbs impurities in the kiln at high temperature, so the fired product shows irregular colors and adheres to different impurities. After the salt is liquefied, a layer of glaze adheres to the surface of the purple clay pot, which makes the purple clay pot lose its color. The double pore structure is changed and it is no longer breathable, which changes the fundamental nature of the purple sand, so that the excellent tea making function of the purple sand pot is no longer.

Burning purple sand pots with a reducing atmosphere to pretend to be firewood is a fraud of the century. It runs counter to the pursuit of the simple, natural and beautiful texture of purple sand, the intangible cultural heritage inheritance process pursued by purple sand pots, and the aesthetic pursuit of purple sand art. Inconsistent, now, some people take advantage of consumers' psychology of pursuing novelty, hype up the so-called firewood purple sand pot, and make it a reason for high prices, and deceive consumers. Such things cannot last for a long time, and they must It has no collection value.
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wave_code
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Fri Mar 24, 2023 11:47 am

Interesting - this is something I had actually wondered about myself. I always figured early factory but also so many Qing and ROC pots I've seen show none of the characteristic of contemporary "wood firing" like the uneven ash glazing despite the fact that they must have been made in dragon kilns. I do have one wood fired nixing that was made in a historical kiln and its quite nice - but it also does have ash glaze to it. Its a very nice pot and performs well, but I can take or leave the ash effect, I was more interested in the special blend of the clay in this case. The cost of wood firing in terms of time, labor, resources, combined with with higher loss rate due to breakage also makes this info also very plausible to me.

The only studio I've seen, at least more western facing, that seems to offer wood fire pots without excessive ash glazing effect is Yann gallery - the clay does look differently colors or differently vitrified than their other pots, but thats it. So I guess there the main effect would just be more the firing temperature? Anyone ever tried and compared their wood and non-wood fire pots?
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LeoFox
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Fri Mar 24, 2023 1:50 pm

Was also told that reduction fire in yixing is called 捂灰 wu hui or cover with ashes. The idea is after a normal firing, some pots may have some color defects. These flawed pots are then fired again with ash under reduction to cover the flaws with the dark reduction coloration
.m.
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Fri Mar 24, 2023 3:44 pm

The way i see it, reduction fired pots, woodfired pots with ash deposits, overfired duanni pots, etc... these are esthetic choices, not a scam or defect. Obviously it is a matter of fashion, and of doing something a bit different, or giving the pot some extra character.
In the past, reduction firing was a way to obtain black or grey pots, which is again an esthetic choice.
The black bone zhuni pots seem to be reduced in the interior and oxidized on the surface, which would suggest that in historic kilns both processes would arise during the course of the firing.
.m.
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Fri Mar 24, 2023 3:49 pm

For example EoT is selling some woodfired pots https://essenceoftea.com/collections/yi ... ing-teapot
These were fired in a wood kiln in Yixing that fires once each month. Each firing takes three days to complete. The pots are placed inside a protective container called a 'xia bo', as used in ancient times to protect the surface from becoming glazed with ash. The wood firing creates a unique finish on the surface, a slight shine & seems to make the water taste smoother and more refined when brewing tea.
Andrew S
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Fri Mar 24, 2023 6:27 pm

Mud and Leaves have posted about both 'wood firing' (https://mudandleaves.com/blogs/teatime/ ... ng-teapots) and reduction firing (https://mudandleaves.com/blogs/teatime/ ... ng-teapots).

I also think that there's no 'scam' here, unless any particular vendor pretends that this process is the same as how pots were fired in dragon kilns in the Qing dynasty. Otherwise, it's just a process that some people seem to like the look of.

I'm not sure what effect it has on the clay, though; clearly, the author of that article thinks that the process negatively affects both the aesthetics of Yixing clay (which is just their personal opinion) and how the clay brews tea.

My only experience is with an LQER reduction-fired pot that I use for high mountain tea, which of course isn't the same as this process.

Andrew
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Bok
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Fri Mar 24, 2023 8:21 pm

Interesting article! Thanks Leo.

Well the scam is to say wood-fired when it is not. I do know from personal hands-on experience in Taiwan how difficult real wood firing is and how high the rate of losses is... definitely nothing that will produce a large amount of teapots that can be sold at low prices. Basically in real wood fired pots you also kind of pay for the ones which got destroyed.

I do like to collect those "accidents" that happend in old times and somehow still have been sold and survived for a century. Kisses of the fire to various and sometimes unrecognisable degrees, crazy discolourations, warping etc. – love it! Looks very different though to what is sold now as "wood-fired Yixing".
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aet
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Sat Mar 25, 2023 12:02 am

2 methods of fake wood firing are known to me.

1) firing in electrical kiln first to the point when clay is stable - no risk of contraction - , then put it in actual wood firing kiln ( discutable if fake as the pot actually went trought the fire on wood , just not all the time )

2) controling various circuts in el.kiln or burners in gas kiln.
I was working in kiln producing manufacture https://en.bvd.cz/ as electrician. The 3 fase el. grid conected to the kiln is devided into the separate circuits which can be manually or automat controled. Like 1 can be left side ( the heating coils on ceramic tubes instaled in the wall ) , 2nd on ther right side , 3rd one at the back or do0r. You can also play around with it , like half there , half here etc.
Basically trick is that you can swithc off one ( or reduce the temperature ) so one side gets colder so different color after burn ( well, you probably can't imitate those flame touches ) .

Tha gas kiln would be more difficult , but also doable. With that , you could achieve flame effect , I believe ( as there are actualy flames involved )

In my experience , mostly the 1st variant of faking is involved , at least in Yunnan , like Jian Shui and other places.

To see how the wood fired kiln looks like , some pictures here. ( in this article different fake BS is descirbed ;-)
https://www.pageoftea.com/black-pottery-disappointment

and here is the one we got our wood fired pottery
https://www.pageoftea.com/dai-tao-potte ... c-minority

Sorry for self promo , if not appropriate , admin please do not hesitate and delete my coment.
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Bok
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Sat Mar 25, 2023 1:10 am

@aet educational as ever, thanks for the links!

The half-wood-fired method is similar to things I have heard in other pottery(not Yixing). Basically just to create the effect, but without the benefit of the prolongued firing a proper wood fire would have (2-3 days upt to a week). Add Sodium(? I think), or just organic matter like hay etc. Result is a sometimes under fired pottery which can be terrible for tea. I have come across these – pretty looking, but suck-the-life-out-of-your-tea potteries in European shops.

Edit: a lot of Bizen ware is looking similar to high fired pottery, but I found many of them actually fired way too low and killing the tea. Pretty but alas, maybe only usable for lower temperature teas...
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