Fun with a Chao Zhou stove

[Tead Off]

Intuit,

The simple solution for Herb is the same one in Asia. Herb needs a wife to tend to these important matters of keeping the fire going. If he can't find one in the U.K., maybe I can find him one here.

[Intuit]

*laughing* Teed, the AGA would have obviated the need for a wife to tend the daily cooking fires.

I wondered about the zinc on the grill plate. Its use is intended for outdoor BBQing. I found one source that mentions a magic number of 740 deg (presumably, deg F) as the upper limit for heating with very low risk of exposure to galvanic metals, but I also know that zinc won't volatilize unless the temp exceeds 880F.

Technical chitchat on galvanized grill plate/mesh use in BBQs:
http://www.finishing.com/217/03.shtml

The author of the replies to the question on zinc vapors from heated galvanized cooking surfaces is somewhat correct in his opinion that there is tendency to overstate environmental exposure risks.

However, he doesn't know this: your body's ability to safely detoxify metals (lung, blood and liver in particular) depends entirely on your dietary intake of a triad of bioactive metals: selenium, zinc and copper. A fouth, iron, is balanced by these three and also plays a role in electron shuffling to metal contaminants that reduces their valence state, making them (a) less reactive in the body, and (b) easier to actively transport and excrete.

Unfortunately, most of us live in areas where these metals are low or scarce in soil abundance, a situation made worse by overworked ag soils that have leached these metals. Dietary deficiency is surprisingly common because plants grown in these soils are also low in these essential metals, as are grazing animals fed plant matter from leached soils.

You would think, "gee, getting a little extra zinc is good". Yeah, but your body is expecting to get it in small doses in food, not by breathing it.

Colorado Pu's cautionary is therefore taken with a grain of salt. If Herb has adequate ventilation in the kitchen, no problemo because the main issue here is combustion gas toxicity with an elevated risk of zinc exposure only if the grating gets really hot in an indoors / poor ventilated environment where he is poised over or near the heat source.

[coloradopu]

thanks intuit ,

with what you have added. i still worry about herb. the pot he uses is ceramic and it can absorb the metals. so then i wonder if it would leach?

its just too much for me to get into. i do not know allot about it all. i just have seen what it has done to welders and the like.

seeing the ceramic tip from the welder and all the galv on it i wonder if it has not deposited on the bottom of the pot? "in small amounts"

i appreciate your trying to explain the facts on this and i bet it is not such a big thing. people like me who know some but not all the facts can get stuff confused. so i too will take your advice. but i will still worry.

[Intuit]

Clay and ceramics are interesting surfaces. They're highly variable in reactive site chemistry because they're derived from a complex mixture of impure components (as you, a potter, well know). Divalent cations like Zn tend to be absorbed onto micro-porous reactive surfaces, but binding concentration will also depend on the efflux rate of the vaporized metal and the surface temperature and chemistry of the vessel. That absorption and desorption (bound metal released from the pot surface) rate will vary with temperature and time.

It's highly doubtful that the zinc will bind inside the pot; metal vapor exposure is to the bottom and lower sides of the vessel. Positive pressure from heating water pushes gases out, won't draw them into the vessel.

[Herb_Master]

After the first use my kettle had dead charcoal inside that crumbled to powder



and the kettle had a fine white powder underneath





But my grating has changed colour



as you can see from my spare (unused) grating



and the partially changed colour of the fire trowel

My builder friend, believes the white powder ash coating and slight perfume will have come from the mechanical oil used in producing the product and which will still coat it until it is burned off. Certainly my 2nd and 3rd sessions did nhot produce the white powder, so it is not likely to have come from the charcoal. His alternative theory is that the grey clay lining of the stove may have been treated to ease use until the stove has been 'burned in'.

Certainly he feels that the first 2 or 3 uses of the stove should not be up to full knockout heat to allow expansion and contraction to stabilise. I believe Imen may have mentioned this, but in my eagerness I used the first fire to brew tea

I have fortunately only been using the stove about 1/10 th full so far, and will build the charcoal level up gradually in accordance with such advice.

But I think my health will survive.

[Herb_Master]

A thin layer of charcoal beneath



while a copious layer is taken to the gas range indoors



and added to the stove



most of the new coals were glowing red when brought out, but by the time the camera was ready had a grey exterior.

With the kettle in place, and an occasional amount of fanning through the chockless vent hole

a teapot [140ml] was selected (first heated with hot water from my indoor kettle)


Some Dragon Tea House Huang Zhi [8 gram]



Then after a while the water starts creeping up the spout of the kettle


Then the lid starts a gentle plopping

When the lid begins to dance, we are ready to brew



and enjoy

and there is still fire left for 3 more brews


though I could add more charcoal now or later to extend the session

[Herb_Master]

Imen is off to China in 10 days time!

She intends to bring me back a goose feather fan or 2 and some Copper Chopsticks!

Drop her a line, if you need anything that she is currently out of stock

[Herb_Master]

http://tea-obsession.blogspot.com/2009/ ... e-set.html

[tingjunkie]

I think I see the problem Herb. Someone has painted almonds black and sold them to you as "charcoal."