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Building a tandoor - what type of clay to use and...


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#1 Mart

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Posted 21 February 2013 - 05:40 PM

(please, do not direct me to those awful "use a flower pot ..." DIY sites :) We like to build a small tandoor. I have seen a used oven clay pot but never a new one so I have no idea, are those pots just dry clay or actually fired in a kiln.
For start, my questions are:

1) What type of clay to use (I was thinking about low fire clay with lots of grog... not sure about the grog part)
2) Do I need to mix something else in to the clay?
3) Do I need to fire the completed pot in a kiln? (if yes, at what temperature)



#2 Iforgot

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Posted 21 February 2013 - 09:18 PM

I would use micaceous clay and fire to ^06 once
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#3 neilestrick

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Posted 21 February 2013 - 09:46 PM

A groggy terra cotta would probably work. If you want it a little less porous, take it up to cone 02 or 01.
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#4 Mart

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Posted 22 February 2013 - 03:19 AM

I am not from US so this cone business needs some calculations. As I understand it, cone 06 can be anything between 969-1023 °C and 02-01 can be anything between 1078-1178 °C depends what cones are used and so on. You guy do not make it easy :)
BTW, cones are meaningless over here. Not a single pottery shop sells "cones" (they actually sell very few useful things) and I have not met anyone who actually uses cones in electric kiln. Honestly.
I'll just get some local low fire groggy clay and use what ever temperature is recommended on the bag.

Cheers

#5 jennko

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Posted 22 February 2013 - 08:01 AM

Some good information about types of clay to use to build a tandoor oven



full article at http://www.nytimes.c...wanted=all&_r=0


Mr. Levy’s first innovation was to fashion the body from a blend of earthenware and stoneware, the former chosen for its modeling and expansion properties, the latter for its ability to withstand high heat without cracking. For porosity (an essential quality so that flatbreads can cling to the oven’s inner walls), he added finely ground fired clay, known as grog. For insulation and extra strength, he developed a clay and vermiculite mixture that could be baked onto the exterior of the pot.

#6 Marcia Selsor

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Posted 22 February 2013 - 08:17 AM

From my experience in Uzbekistan I'd say this oven is made from a refractory castable just by examining the construction and how it is built into the wall. There could possibly be a large ceramic pot built into a permanent position covered with a concrete type of material. The bread is baked on the wall til it drops. A ready hand catches it.

Marcia

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#7 Mart

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Posted 26 February 2013 - 12:54 PM

Thank ya'll for taking your time to answer. I found some type of "fire proof" (no idea, what the correct translation is :) ) clay that withstands the thermal "shock" of temperature changes. I am going to build a small one out of this stuff and see what happens...

#8 Marcia Selsor

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Posted 03 March 2013 - 12:28 PM

From my experience in Uzbekistan I'd say this oven is made from a refractory castable just by examining the construction and how it is built into the wall. There could possibly be a large ceramic pot built into a permanent position covered with a concrete type of material. The bread is baked on the wall til it drops. A ready hand catches it.

Marcia


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#9 Olesya

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Posted 09 March 2013 - 10:50 PM

Hello everyone,

If anyone is interested, I am posting a video of how tandoors are made in Uzbekistan and Turkey. One of them is however in russian, the other is in turkish, but i think the narration in this case is not important :






http://www.youtube.com/watch?v=CmwjqWdGgcQ


http://www.youtube.com/watch?v=f_ylzxtLGjQ

I too really want to build one, but I am far from being a specialist in ceramic and I do not know the terminology. I bought some firing clay and this is what was written on the label:

Albaster Fine Firing Clay.
Firing clay cone 04 to 2. Shrinkage of 8% and porosity of 4% at cone 02.


Do you think this material would be suitable to build a Tandoor?




#10 Mark McCombs

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Posted 10 March 2013 - 01:53 AM

Wonderful videos. Thanks for sharing the links.

I am curious as to what was the white, fibrous additive that was used at the end of the second (2/3) video.
Looks like it was used as a finishing coat on the tandoor.
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#11 Olesya

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Posted 11 March 2013 - 12:17 AM

Wonderful videos. Thanks for sharing the links.

I am curious as to what was the white, fibrous additive that was used at the end of the second (2/3) video.
Looks like it was used as a finishing coat on the tandoor.



I cant tell you exactly because I dont speak Turkish. But from what I can see it is cotton fiber. But I know for sure that in Uzebakistan, they add goat or camel wool to the clay. The wool is used to solidify the clay, so there will be no fissures. After, when the tandoor is fully heated, the wool will burn and you will be left with micropores that will help with the heat conducting in the oven.

Do you have any recommendations for the clay?

#12 Marcia Selsor

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Posted 15 January 2014 - 08:21 AM

I know in Uzbekistan they add cat tail weed fuzz into the earthenware when adding handles. The shredded stuff on the ground when they are building ovens could be wood shavings, straw, wool as you mentioned all would serve to bind and make porous.
Great videos.I loved the bread from these ovens and I have some tools for putting pinholes in the center of the bread to make it cook more evenly, less doughy.
I would think a raku clay body would work best for these, or one where you add something for the porosity


Thanks.

Marcia

#13 Norm Stuart

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Posted 15 January 2014 - 02:34 PM

Mart -

Since you buy your clay from Frankfurt, there's no reason you can't buy your Segerkegels or Ortonkegels (Orton Cones) from Köln or Dortmund.

http://www.reimbold-.../en/orton-cones

http://www.reimbold-.../ortonkegel.pdf

http://www.toepferho...segerkegel.html

http://www.marienfel.../segerkegel.htm

http://shop.keramik....ormalkegel.html

200837882011_2.jpg

 

You verify the total cone accumulation delivered by your firing program using the zeuge that the kegels provide.  http://de.wikipedia....wiki/Segerkegel

cones%20%26%20stand.gif

After all, they were developed by a German chemist, Herman Seger, around 1870.  But Ortonkegels are now really the only kegels used, even in Deutschland.

I am not from US so this cone business needs some calculations. As I understand it, cone 06 can be anything between 969-1023 °C and 02-01 can be anything between 1078-1178 °C depends what cones are used and so on. You guy do not make it easy smile.gif
BTW, cones are meaningless over here. Not a single pottery shop sells "cones" (they actually sell very few useful things) and I have not met anyone who actually uses cones in electric kiln. Honestly.
I'll just get some local low fire groggy clay and use what ever temperature is recommended on the bag.

Cheers



#14 Tyler Miller

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Posted 15 January 2014 - 02:42 PM

I would just use an earth-dug sandy-clay type mud, straw, and horse manure.  Roughly 75% clay, 20% straw, and 5% horse manure by volume.  Maybe substituting a lot of the straw for cotton, wool, or horse hair?  It worked for Quebec ovens, ancient and medieval kilns, and a few charcoal forges and remelters I've made.  :)






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