Author Topic: An Open Call to Ceramic Engineers- Reverse Engineering Biscotto di Sorrento  (Read 8688 times)

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Offline shuboyje

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I was talking to an owner of a four grand mre F 1030C about the benefits of a Biscotto floor, and He put terracotta baseboards as a temporary mod to tryout.

He is quite happy with the result,

before that he was burning the bottom of his pies when the floor temperature was above 750-770F.

AND those terra-cotta tiles are not easily available in the US.  I've worked on renovation project of old buildings with terra-cotta walls,  structural terra-cotta in the US is very hard to get and expensive. 

If anybody knows otherwise I'de love to know, they do look like a really nice material to build a neapolitan vent out of like the Italians do.
-Jeff


Offline stonecutter

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I've been looking for years too, for other masonry projects. I do have a couple companies that may do it, I'll check when I'm back in SC on Monday.
http://oldworldstoneandgarden.com/


When we build, let us think that we build for ever.
John Ruskin

Offline Iowamcnabb

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I've read the thermal conductivity of cordierite is 3 w/mk   Does this sound right?  I've not had burnt bottom problems on my makeshift oven using 1 and 1/4 cordierite?
« Last Edit: August 15, 2014, 11:35:30 AM by Iowamcnabb »

Offline TXCraig1

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I've read the thermal conductivity of cordierite is 3 w/mk   Does this sound right?

Yes, that is correct.
Pizza is not bread.

scott123

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Cordierite can range in conductivity, depending on how it's manufactured.  It can range from 1.5 w/mK to 3 w/mK.  I have found that the lower conductivity generally corresponds with lower density cordierite.

Offline TXCraig1

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Please post an example of a cordierite stone/shelf meaningfully under 3 W/mK.

BTW - the thermal conductivity of Cordierite is 3.0 W/mK. While you may be able to structure a product in such a way that the conductivity of the product is lower, the conductivity of Corderite doesn't change.
Pizza is not bread.

Offline Iowamcnabb

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Why are those of us using cordierite not burning the crap out of the bottom of our pies at 3.0 while others with less conductive bricks struggling?

Offline TXCraig1

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Why are those of us using cordierite not burning the crap out of the bottom of our pies at 3.0 while others with less conductive bricks struggling?

My guess is you don't have enough mass in the deck for it to be a problem. How hot is your deck before and after baking?
Pizza is not bread.

Offline Iowamcnabb

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My guess is you don't have enough mass in the deck for it to be a problem. How hot is your deck before and after baking?

When I just had one 5/8 inch stone the pies would need to be domed after 15 seconds or they would burn.  When I placed a second 5/8 stone on top they didn't have to be domed at all launching at 800 to 850.  The deck is 700 or so 30 minutes after I've finished. 

Offline TXCraig1

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I meant before and after baking a pie. What is the temp when you launch and when you retrieve the pie - i.e. how much does the temp drop?
Pizza is not bread.


Offline TXCraig1

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When I just had one 5/8 inch stone the pies would need to be domed after 15 seconds or they would burn.  When I placed a second 5/8 stone on top they didn't have to be domed at all launching at 800 to 850.  The deck is 700 or so 30 minutes after I've finished.

You have a heating element below the bottom stone, right? Sounds like the heat was passing quickly through it with one stone and burning the pies. Adding a second stone doubled the thickness which in and of itself halves the rate of heat transfer and also introduces an air gap which would drop the conductivity of the system (stone-air-stone) dramatically as compared to stone alone.
Pizza is not bread.

Offline Iowamcnabb

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I generally launch the first pie at 820 or so and usually launch the second pie 5 minutes after the first at about the same temperature.  I'll check the deck this week right after the first pie comes out. 

I only have the one top element.  I decided against a bottom element in favor of really good insulation. 

Offline TXCraig1

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My guess is that the drop will be significant.
Pizza is not bread.

Offline sub

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I' really happy with my terracotta stone in my G3Ferrari, no burn bottom or bad taste even at 970F

My homemade clay stone is drying well.

Offline stonecutter

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Sub, what was your mix design for the tile?
http://oldworldstoneandgarden.com/


When we build, let us think that we build for ever.
John Ruskin

Offline MotoMannequin

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My guess is that the drop will be significant.

Jumping into an old thread here but I believe Craig is correct Cooking on a BGE with a stack of Cordierite stones over 1" thick, doing 2-minute pies with the stone in the 750F range, I found that I had to let the stone warm up for a few minutes after pulling a pie off, before it was hot enough to cook the next. Conductivity doesn't matter so much if there's not enough mass to hold temperature.

I'm in the planning stages for a low-dome brick oven in my back yard, and this thread has been a fantastic read. Thanks Sub!

I think I have answered all my burning questions, except for floor material, which I'm pretty stressed about. The our local building supply is unable or unwilling to provide any data on their firebricks. They're even trying to convince me to build out of clay bricks since that's what all their contractors do. The firebricks I think are fine for the dome, but I won't use them as floor material unless I can verify the conductivity somehow. Any suggestions? Heat up a brick and measure the rate of cooling? Does the weight of the bricks tell me all I need to know?

At this point I have no faith in the floor tiles that Forno Bravo sells.
« Last Edit: October 14, 2014, 01:42:00 PM by MotoMannequin »

Offline Tscarborough

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Use low duty firebrick like those manufactured by Whitacre-Greer in Ohio.

Here is their data sheet:

http://www.wgpaver.com/wp-content/uploads/2013/05/Product-Data-Buff-Firebrick.pdf


Offline Donjo911

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Not to confuse the matter.  This may not even be relevant however,  I was watching one of those Ancient Civilization shows. In this case, it was the Roman Empire. The explained how the Romans engineered aquaducts across long uneven terrain; building combounds and technique to assemble and upright giant columns and facades, etc.,  They spent a fair amount of time explaining the geology of Italy, the use of Volcanic ash, and other (I wish I could remember) Volcaninc soil, due to it's mineral make up and so on.  When I saw it - It sounded like what I have read is "Biscotto di Sorrento"  I remember them saying that it was the genius of the Romans along with the good fortune of being in a volcanic area that allowed them to develop these kind of "technologies."  I'll see if I can find it but they had a British Historical Geologist duplicate the method of creating the Romans' light but very strong materials - perhaps there are some bread crumbs to follow there?  Or is it Pizza crumbs?  I'll see what I can find.  I watch a lot of History, Nat Geo, etc. It was assuredly on one of those channels. 
Cheers,
Don
I have done wrong.. but what I did, I thought needed to be done.

Offline MotoMannequin

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Use low duty firebrick like those manufactured by Whitacre-Greer in Ohio.

Here is their data sheet:

http://www.wgpaver.com/wp-content/uploads/2013/05/Product-Data-Buff-Firebrick.pdf

Thanks TS. Looks like they have a dealer in San Rafael. I'll contact them.


 

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