Additives in Yixing Clay and Impact on Clay Quality

[beachape]

I recently read Youzi's blog articles on Yixing manufacturing (https://www.teapotandtea.com/modern-yix ... ng-method/ and am also intrigued by description of some pots on teaswelike.com regarding use of Barium carbonate in modern yixing. This is a great blog, but I was left with a few questions:
1) Barium carbonate, I believe, prevents efflorescence in the clay. How does it negatively impact the quality of the clay specifically? Does it decrease porosity? Change the crystalline structure?
2) How do other additives impact the clay quality specifically for brewing? In the article, it is noted that the addition of acid "removes all impurities from the clay. However, it also destroys its structure and unique attributes which makes Yixing Zisha special." I'm curious to learn more about how these additives specifically degrade the quality for brewing.
3) I've heard that F1 pots after 1980s and 1990s, and almost all modern pots, frequently have additives. I've also heard vendor claims about stashed hoards of antique pure clay. Are these claims mostly false, or is it still possible that potters could be working with pre-modern additive-free clay?

Thank you!

[Youzi]

I recently read Youzi's blog articles on Yixing manufacturing (https://www.teapotandtea.com/modern-yix ... ng-method/ and am also intrigued by description of some pots on teaswelike.com regarding use of Barium carbonate in modern yixing. This is a great blog, but I was left with a few questions:
1) Barium carbonate, I believe, prevents efflorescence in the clay. How does it negatively impact the quality of the clay specifically? Does it decrease porosity? Change the crystalline structure?
2) How do other additives impact the clay quality specifically for brewing? In the article, it is noted that the addition of acid "removes all impurities from the clay. However, it also destroys its structure and unique attributes which makes Yixing Zisha special." I'm curious to learn more about how these additives specifically degrade the quality for brewing.
3) I've heard that F1 pots after 1980s and 1990s, and almost all modern pots, frequently have additives. I've also heard vendor claims about stashed hoards of antique pure clay. Are these claims mostly false, or is it still possible that potters could be working with pre-modern additive-free clay?

Thank you!

Starting form 1980 they started to add more and more stuff into the clay. Vendors mostly claim that their pots are made of old stashed away clay, they don't claim its pure. During the state operation era, there was only one mining and processing company, the state owned one.

So everyone got their clay or the ore from there. From the 80s and 90s is the time when other studios, factories start to open, besides F1, but the mining is under state control. The state owned mining company and F1 got dissolved together around 1997, and the ore and processed clay got sold off.

For some reference for these you can see Kyarazen's video about Yixing history.

[beachape]

Thanks Youzi! Appreciate any additional resources or comments to learn more about how the additives impact clay quality. Also, would you say that most pre 1980s clay should be reasonably good, or was there a lot of variation?

[Bok]

Thanks Youzi! Appreciate any additional resources or comments to learn more about how the additives impact clay quality. Also, would you say that most pre 1980s clay should be reasonably good, or was there a lot of variation?

All without additives, yet some batches are better than others. But for the average consumer I’d say these tiny differences are of little consequence.

[Youzi]

Thanks Youzi! Appreciate any additional resources or comments to learn more about how the additives impact clay quality. Also, would you say that most pre 1980s clay should be reasonably good, or was there a lot of variation?

Depends on what you mean by clay quality. For me, it's just how close it is to the result achieved by using the traditional process.

There isn't much research done about how differently processed teapots from the same ore change the attributes of tea brewed in them. That's why I didn't mention anything about this subject.

So all you'll hear is just hearsay and speculation and theories, so you are free to choose your own believes.

[StoneLadle]

High performance clay Vs artist clay Vs whatever...

Taste them man... But easier to do in the East than West...

[beachape]

Thanks Youzi. I think that is a very reasonable interpretation. I have a few hongni F1 pots ranging from 60s, 80s, and 90s. It's hard for me to compare them directly, because they all have different sizes and properties (fast/slow, thick/thin). I also own some 90s Malaysian commissioned DiCaoQing pots from EOT that I like most of all. It is hard for me to say that the modern, likely additive-containing, pots are worse than the others. Seeking traditionally processed pots seems like a good thing, but I am also skeptical that the additives alone are the problem. I'll be sure to keep reading your blog, which is very informative and well written.

[Bok]

Went to have tea with some collectors last night and mentioned how Westerners now do not really want anything past green label due to additives (after the short period of excitement to be able to access any F1 at all).

They were quite puzzled by this reasoning. They understand the visual part, as most of late 80-90s is quite ugly, especially the Biaozhun lines and their atrociously looking lids... but health concerns?

Is there actually any evidence that those additives do any harm? The way I see it a lot of other things will kill you likely before any of that kicks in, air pollution, water if you live in certain parts of the US, COVID, whatever...

Somehow it feels like just another hysteria pushed by half-knowledge and lack of any empirical evidence. Is it?

[Youzi]

Went to have tea with some collectors last night and mentioned how Westerners now do not really want anything past green label due to additives (after the short period of excitement to be able to access any F1 at all).

They were quite puzzled by this reasoning. They understand the visual part, as most of late 80-90s is quite ugly, especially the Biaozhun lines and their atrociously looking lids... but health concerns?

Is there actually any evidence that those additives do any harm? The way I see it a lot of other things will kill you likely before any of that kicks in, air pollution, water if you live in certain parts of the US, COVID, whatever...

Somehow it feels like just another hysteria pushed by half-knowledge and lack of any empirical evidence. Is it?

It's mostly just Barium carbonate, and that too is only in lower concentration, like 0.1-0.5%.

That has to dissolve into your tea in enough dose and stay there for long enough to do any harm.

I wouldn't be too worried about it neither.

[.m.]

It's not about the medical risk. It's all about Purity. And rat poison makes bad Vibrations.

[Bok]

It's not about the medical risk. It's all about Purity. And rat poison makes bad Vibrations.

For me it’s mostly cosmetic, I dislike the sheen of the newer pots and the lack of sense of shape and proportions...

[.m.]

Me too i'm quite a bit weirded out by the shine of a lot of new pots. Not sure whether it is through additives or just through meticulous burnishing to a point that wasn't usually done in the old days.

Here's some technical reading about BaCO3: https://digitalfire.com/material/barium+carbonate

[wave_code]

Went to have tea with some collectors last night and mentioned how Westerners now do not really want anything past green label due to additives (after the short period of excitement to be able to access any F1 at all).

They were quite puzzled by this reasoning. They understand the visual part, as most of late 80-90s is quite ugly, especially the Biaozhun lines and their atrociously looking lids... but health concerns?

Is there actually any evidence that those additives do any harm? The way I see it a lot of other things will kill you likely before any of that kicks in, air pollution, water if you live in certain parts of the US, COVID, whatever...

Somehow it feels like just another hysteria pushed by half-knowledge and lack of any empirical evidence. Is it?

This is an interesting point and something I've thought about quite a bit as I started buying more pots... generally pre-90s pots were out of my price range so I've tried looking more into good quality modern pots, particularly non-yixing. Doing so meant also thinking about what do I want to get/expect to get out of a pot. With junky cheap pots for me there is the mix of concern that both the clay will affect the tea adversely rather than enhance it, which if its really low grade clay is quite likely, as well as that there might be toxic things like heavy metals in the clay. Of course there is still a matter of trusting the source and thereby also the maker, but a modern pot to me from a good source I don't see as a necessarily worse than pre-90s. But also I drink teas that aren't known for being quite as difficult to brew as others, so while I do notice differences between brewing the same tea in different pots and do tend to favor certain ones I'm still not too overly picky - more that a different pot shows different aspects of the tea. The grade of tea I tend to drink is a factor too - while I've gotten a hold of more and more higher grade and older tea I'd certainly be happy to some day have the chance to try making it in a vintage pot to see what it does, I don't think what I experience with good water and good attention necessarily so much worse off - or at least even if it may or may not be as good, what I'm getting certainly isn't bad and what I don't know in this case can't hurt me so I don't stress over it.

I think a lot of the western view around pots can come from this idea of what we are told over and over (often by vendors of course but it gets taken to heart) is the 'best'. I think it can be a mix of fomo/status, wanting 'the best', parroting what 'tea wisdom' we have heard rather than trying things for ourself, and health concerns all mixed together. When in fact most of the time to enhance one's tea experience what one probably needs once they have a halfway decent pot or gaiwan is better tea, or maybe water and practice brewing. But instead the pot becomes this thing that is easy to point to and say 'if I had that my tea would be better'. A lot of people want things to be less complicated or more prescriptive than they are, and insisting on getting/using what you have heard is the best is one way of how I think some people deal with that even though we know the world doesn't work that way - especially the world of tea where things change so much based on weather, time, processing, so on. While some people certainly have a trained enough palette I do wonder with certain people if they had to do a blind tasting between a vintage and a high quality and equally seasoned modern pot what the results would be preference taste profile wise, or who could really tell the difference.

As for health concerns beyond things like ebay trash pots that straight up smell/taste off I'd also love to see more info/research on what additives are common and what their effects are both in the clay's structure and or any possibility of leeching, or if they are stable or totally benign. I suppose its similar to the formaldehyde thing with furniture - lots of junky bad furniture can contain high amounts of formaldehyde and other nasty chems as binders/stabilizers, glues, coloring agents, so on... and while you don't want things like that around and off-gassing, there are people who are worried or take claims to the other side and want formaldehyde free furniture - however wood/trees produce formaldehyde naturally, and while a piece of oak is different than junky chipboard, no wood furniture is 100% formaldehyde free and anyone who claims it to be is stretching the truth to market on fear. I'll be the first to admit though I'm still trying to figure out when am I being careful, or when am I being unnecessarily concerned. I saw Chawang recently started selling some really nice looking huaning pottery both glazed and unglazed- both look lovely and I love the woodfire character of the raw clay and the variegated sea green. But despite them being modern I can't get this thought out of my head about what if the clay has things I don't really want in there, or could the glaze leech something bad? But if its a modern glaze there should be no issue, and if I have ikea plates theres probably just as high of a chance they would do the same.

Sorry if its already discussed elsewhere but maybe someone who knows more can shed light on this- I understand kaolin is another common additive in more modern clay, which is a component of porcelain. So I'm guessing the downside with that additive is that its used to stretch the supply as well as harden the clay (would this be done to prevent cracking /losses during firing?), so in addition to there being less ore in the clay that it is also making it less porous in the process?

[Bok]

I think it can be a mix of fomo/status, wanting 'the best', parroting what 'tea wisdom' we have heard rather than trying things for ourself, and health concerns all mixed together. When in fact most of the time to enhance one's tea experience what one probably needs once they have a halfway decent pot or gaiwan is better tea, or maybe water and practice brewing. But instead the pot becomes this thing that is easy to point to and say 'if I had that my tea would be better'. A lot of people want things to be less complicated or more prescriptive than they are, and insisting on getting/using what you have heard is the best is one way of how I think some people deal with that even though we know the world doesn't work that way - especially the world of tea where things change so much based on weather, time, processing, so on. While some people certainly have a trained enough palette I do wonder with certain people if they had to do a blind tasting between a vintage and a high quality and equally seasoned modern pot what the results would be preference taste profile wise, or who could really tell the difference.

Exactly this!

[TeaTotaling]

High performance clay Vs artist clay Vs whatever...

Taste them man... But easier to do in the East than West...

@StoneLadle Good to have you back in rotation. I thought you might have been banned for inciting too much thought amongst the masses God forbid anyone think freely in the realm of public discussion.

When seeking modern pots, my sweet spot is an artist who uses high performance clay. The place where art, function, and performance meet harmoniously. Oh what a satisfying marriage this makes. Of course, I'm vastly limited by what I have access to, but I try to do my best. It would seem more senior artists might have access to better clay, both for working and brewing.

I have also read that clay from Jin Lin Chuan Sha (金林传砂) is highly sought after, and pure. Not sure if this is more marketing, or if indeed experienced artists and collectors desire this clay?