Green clay yixing toxic?

[isaac]

Is the green clay yixing toxic?

I heard that the green clay is made by adding additives to luni resulting in a green colour. The bright green colour is best avoided. The duller green might be worth a try.

Recently i bought a green clay yixing teapot. After seasoning the pot, I found that there is a 'funny' (read unwanted) smell in the teapot the next day.

I was told that I will need to season the teapot every day for two months before the smell will go away. The method is to put the tea leaves in the pot and leave overnight.

My thinking is that all that will do is to have the tea fragrance infused into the teapot but will not get rid of the toxic materials in the teapot. Because the toxic materials would have already fused with the clay as part of the firing process.

All these are just logical guesswork on my part.

May I know if anyone here has the same sort of experience?

Thank you.

[Alex]

I remember reading that green is usually for display only but my knowledge of clay is low so I'll let some one else chime in.

[David R.]

From Hojo's website : [link]

"Zisha is the mixture of 3 clays, red clay, purple clay and green clay."

"Green clay is a very strange clay. The primary mineral inside green clay would be copper. It makes the aroma very strong, yet it completely eliminates flavor. I find the taste quite flat. This clay is only suitable for displaying purposes."

[isaac]

My thanks to both of you. That explains the funny smell that will not go away.

I did told the seller that i will be using it for tky and they said it is very suitable and that the more i use it the more beautiful it will be.

Still it is a very beautiful set. My tuition fee, albeit an expensive one.

Thanks again, Cheers

[JBaymore]

Copper is not heavily toxic, like lead and cadmium, but it really can affect the taste of foodstuffs, even in small amounts. If the copper is in the porous clay body formulation and not in a fully fused glaze, it is reasonably likely to have some leaching issues.

For some people with a particular disease, copper even in small amounts, can be really bad up to the level of fatal.

As to the vendors knowing what they are talking about with any of this stuff...... caveat emptor.

best,

................john

[shyrabbit]

John,
Thanks for your post. I was particularly piqued by your statement that copper leaching can be fatal to people with "a particular disease"...Wow, I was not aware of this. Please, what might this disease be? I am more than curious. Thanks in advance for your response.
Michael

[auhckw]

Copper is not heavily toxic, like lead and cadmium, but it really can affect the taste of foodstuffs, even in small amounts. If the copper is in the porous clay body formulation and not in a fully fused glaze, it is reasonably likely to have some leaching issues.

For some people with a particular disease, copper even in small amounts, can be really bad up to the level of fatal.

As to the vendors knowing what they are talking about with any of this stuff...... caveat emptor.

best,

................john

So it means isn't a good idea to buy this?
http://www.teachat.com/viewtopic.php?f=36&t=13915

[JBaymore]

Michael,

It is called Wilson's Disease. It is rare, but it is out there. It screws up the body's ability to metabolize copper. Mainly a liver based disease. Copper is not a huge normal nutritional need, but we do process some minute amount of it. With Wilson's Disease, the body cannot rid itself of copper. It eventuially builds up to toxic levels.

best,

................john

[JBaymore]

So it means isn't a good idea to buy this?
http://www.teachat.com/viewtopic.php?f=36&t=13915

A person with Wilson's Disease will KNOW that they cannot use something like this. They know it beacuse it is clearly labeled as containing copper.

The real PROBLEM is when they are getting copper from something from which they do not KNOW that they are receiving copper.

Maybe like the aforementioned teapot .

best,

.................john

[gingkoseto]

I think it's tedious to season the teapot for 2 months before use. Even if some people do it, I guess it's for gaining patina instead of removing the new pot odor. The new pot odor normally shouldn't last that long.

There can be metal salt (good or bad) added to yixing to manipulate green/blue color. Good examples were made by some yixing artist (very few of them though, such as Zhu Dan). Bad examples were made by illegal merchants. Teapots made with natural green clay are quite common. I didn't think they were much different from clays of other colors on human health. But John, that's good information and it's nice to learn what elements there may be in the clay!

[britt]

I have a green clay or Lu Ni Yixing I purchased from Jing Tea Shop more than two years ago and I have had no problems or complaints with it. It was recommended for use with Wuyi oolong and I tried it and immediately dedicated it to that. Compared to the pot I was previously using, I thought this one produced better-tasting Wuyi. It looks somewhat blue in the picture but in reality it is green.

[shyrabbit]

John,
Thanks for your response...I truly had no idea.
Michael

[shyrabbit]

John,
Yes, it seems this disease is, in fact very rare, approx. 1-4 per 100,000. I think this level of concern is far below what I as a potter can effect.
Thanks for the info John,
Michael

[JBaymore]

John,
Yes, it seems this disease is, in fact very rare, approx. 1-4 per 100,000. I think this level of concern is far below what I as a potter can effect.
Thanks for the info John,
Michael

Yup, it is a rare condition. But it exists. It may be rare, but if you are the one who suffers with it....... it is certainly a significant health issue.

As a proferssional educator that teaches information of ceramic toxicology, it is something that I communicate to students. Copper is a particularly hard colorant to keep dissolved in glaze melts. We talk about that fact also.

That is stuff they need to know. What they eventually do with the information is thier business.

best,

..............john

[Tead Off]

I have a green clay or Lu Ni Yixing I purchased from Jing Tea Shop more than two years ago and I have had no problems or complaints with it. It was recommended for use with Wuyi oolong and I tried it and immediately dedicated it to that. Compared to the pot I was previously using, I thought this one produced better-tasting Wuyi. It looks somewhat blue in the picture but in reality it is green.

Hojo states that green clay eliminates taste. I'm assuming you are refuting his statement when you say you are getting better tasting Wuyi from it. So, you can still taste the tea using green clay. Maybe Hojo's statements are not translated properly.

I've never heard of any tea people recommending green clay over red and purple clays but the green clays are naturally occurring in yixing. If they are using green clay without additives, firing the pots high enough where porosity is not an issue, I don't think they are toxic. But, I can't speak for people who may have hyper-sensitive conditions.

No teapot should smell when brewing tea or just plain hot water in it. Good yixing has the same aroma as heated stone. I would never use or even attempt to season a teapot that smelled. Something is wrong.