Tuesday, September 09, 2008

Keep the tea pleasure pure

There are 2 subjects that can spoil a tasty family meal: illnesses and politics (unless everybody votes for the same party). Several members of my family are in the medical field, so I often get to listen to graphic description of patients' conditions while eating. And some diseases don't even need a description to cut my appetite.

To enjoy food or tea, the state of mind is very important. That's probably why I prefer to look beyond the health benefits of tea. It's just not relaxing to think of all those diseases tea is supposed to protect us against. Tea won't make us immortal, but a perfect cup of tea can taste divine.

But there is an even more disturbing thought: tea could be unhealthy. In this regard, the most recurring fear is that of lead in tea accessories. And this is not something that can simply be thought away. To find my peace of mind, I tested various ceramics 2 years ago. On the Teachat forum, others have also obtained negative results.

I think we can put this concern about lead to a complete rest for most tea ware. Most earth ware (like Yixing pots) and porcelain are fired at temperatures above 1200 degrees Celsius to succeed. Even potteries made at low temperatures still exceed 800 degrees Celcius. Lead, however, melts at 327.5 degrees Celsius. Fired at a temperature above 327.5 degrees, lead would melt and flow to the bottom of the piece (easy to spot by eye). So, the only way there could be substantive amount of lead is if it were added after the firing, as part of a decoration. A plain earth ware teapot would loose its shape if it contained melted lead. The main risk I see, therefore, are accessories with fragile (color) ornaments that look like having been added after firing. These decorations may (or may not) contain lead.

11 comments:

ginkgo said...

très belle ronde de théières !

au sujet du plomb, je sais qu'en Europe certains émaux ( vert notamment) contenaient trop de plomb ; le plomb rend les émaux de basse température brillants. Mais ensuite il y a eu 1 législation pour contrôler le surplus de plomb dans ces glaçures.Cela ne concerne pas les céramiques en grès ou en porcelaine mais uniquement les terres rouges ou autres cuites de 980° à 1100° environ et que l'on trouve sur le pourtour du bassin méditéranéen.
Je ne pense pas qu'il y ait le moindre risque pour les objets utilitaires fait en terre non émaillée comme les théières de yixing sauf éventuellement comme tu le mentionnes s'il y a une décoration rajoutée et que la pièce est recuite plus bas pour cela.
Donc pour les belles théières de yixing ,même anciennes, aucun risque (à mon avis ).

eileen said...

Thank you for this post. It has been on my mind for quite awhile because some merchants in Montreal were warning about lead in teapots. Before that it hadn't crossed my mind. I hope many folks see this entry. The art, as usual, is stunning. Thank you.
Eileen Feldman

Stephen said...

I think that most of the concern comes because the lead is gradually eroded in time. In the same way as water pipes have been since the Romans. I also know there to be problems with soda glass which is used for some glass tea pots.

Thomas said...

Très belle série de photos!

Réunies ainsi autour de la tasse, on les croirait facilemnt vivante... je vois qu'il y a aussi pas mal de nouvelles têtes dans cette réunion...

Veux-tu suggérer qu'en raison de la très haute températures de cuisson des grais de yixing, ce n'est pas possible qu'il y ai du plomb dedans?

Stephane said...

Merci Ginkgo pour tes précisions professionnelles.

Thanks Eileen for your kind words.

Thomas,
Oui, c'est cela que je suggère. Et cela semble confirmé par de nombreux tests.

Tea Escapade said...

Great post. I appreciate the knowledge. I have seen this question arise on a few occasions, but really had not taken the time to research. Thanks again for sharing.

Fredrik said...

Just a question,,,
Do you understand chinese? =P
I study chinese, and I'm very into tea right now...that's the reason for asking =P

Stephane said...

Fredrik,
I've been living in Taiwan for the last 12 years and my wife is from Taiwan. I've learned Chinese through immersion and understand most normal conversations (I also talk Chinese). However, I don't write Chinese, but can recognize most common characters in relation with tea.

Fredrik said...

OK =)
I've been to Taiwan, and I love it, next time I go there its going to be a tea trip =P!!

Ido said...

an amazing entry!

Thank you for the useful information and resting my mind if only for a bit... .

Fellow Tea lover said...

I thought that most of the tea grown in Taiwan the best tea anyway is in Taiwanese speaking areas.