Author Topic: Are these the right bricks for my Neopolitan oven?  (Read 5400 times)

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Online sub

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #25 on: September 14, 2013, 02:13:34 PM »
Hi Christian,

Raffaele Vassallo who used to work with Stefano Ferrara uses unistara STARMAX firebricks in his oven.

Quality: alumina <35%
Refractory brick pressed dry and is widely used in the production of fireplaces, grills and barbecues. Available in two colors.
chemical composition

     Al2O3 + TiO2 [%]: 19-21
     Fe2O3 [%]: 1.5

physical Properties

     Bulk density [kg/dm3]: 1,850
     Apparent Porosity [%]: 20
     Resistance to cold compression [kg/cm2]: 320
     Refractoriness under load [° C]: 1210


Offline shuboyje

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #26 on: September 14, 2013, 02:24:14 PM »
Hi Christian,

Raffaele Vassallo who used to work with Stefano Ferrara uses unistara STARMAX firebricks in his oven.

Quality: alumina <35%
Refractory brick pressed dry and is widely used in the production of fireplaces, grills and barbecues. Available in two colors.
chemical composition

     Al2O3 + TiO2 [%]: 19-21
     Fe2O3 [%]: 1.5

physical Properties

     Bulk density [kg/dm3]: 1,850
     Apparent Porosity [%]: 20
     Resistance to cold compression [kg/cm2]: 320
     Refractoriness under load [° C]: 1210

But these are in the dome, he is using Biscotto for the floor.  The conductivity of the dome is irrelevant since it doesn't transfer heat to the pizza by conduction. 
-Jeff

Offline Tscarborough

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #27 on: September 14, 2013, 04:16:49 PM »
Not only does vacuum forming increase the density it also decreases the size of the pores.  That is why they have better absorbtion numbers.  Vacuum forming may be common in fire brick production, of the 2 producers that I am familiar with, one does and one does not.  And the one that does not is only 20 miles away and we still rail the W/G in from Ohio, that is how much better (because they are not cheaper) they are.

Offline TXCraig1

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #28 on: September 14, 2013, 07:50:20 PM »
Not only does vacuum forming increase the density it also decreases the size of the pores. 

This is the key. Pore size is likely the second most important factor (behind density) with respect to conductivity, AOTBE.

As Tom noted, this is a function of the manufacturing process explaining why process matters. It also explains why the WG LD buff firebrick has such low conductivity.

1) Since conductivity is directly correlated to density, it stands to reason that AOTBE, the material with the larger pore size will be more conductive because it will therefore have less pores and areas of higher density. This is confirmed by the model in this paper: http://web.ornl.gov/sci/buildings/2012/1992%20B5/013.pdf

2) At high temps, radiant heat transfer will also be a factor. Heat moves through a porous material by thermal IR in addition to conduction. The higher them temp, the more IR is a factor (a fourth order relationship). When it comes to IR, I suspect the smaller the pore size, the less efficient the heat transfer as the thermal energy must be emitted, absorbed, and readmitted more and more times as the pore size gets smaller.

So, the efficiency of both conduction and radiant transfer decrease with pore size, thus smaller pore size = lower thermal conductivity, AOTBE.
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Offline stonecutter

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #29 on: September 14, 2013, 11:03:18 PM »


This is true, but there is little to no knowledge of Neapolitan ovens there, and little to no knowledge of the importance of thermal conductivity for the floor there.  If you want to build a Pompeii style SUV of an oven it is a great place, but if you want to build an oven to cook 60 second Neapolitan pizza there is a bit of a knowledge gap there.

That depends on who gives the feedback.
« Last Edit: September 14, 2013, 11:09:27 PM by stonecutter »
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Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #30 on: September 17, 2013, 11:26:10 AM »
Wow, thanks for all the info, this is the most complete answer I got ever on any message board.

As suggested I called to know the heat conductivity numbers and got this by email:

Quote
Bonjour Monsieur,
 
Voici des valeurs typiques de conductivité thermique pour des réfractaires denses silico-alumineux  (température °C/lambda en W/K.m) :
 
30% Al2O3 : 200°/1.15 ; 600°/1.25 ; 1000°/1.3
40% Al2O3 : 200°/1.20 ; 600°/1.3 ; 1000°/1.35
60% Al2O3 : 600°/1.6 ; 1000°/1.65
 


So, not what I'm looking for. When I explained my situation he said that what I was looking for is isolating refractory bricks. Those bricks do have the  W/K.m values I am looking for.

But, and please excuse my complete n00b question here, is this even feasible? Because I guess this forgoes the whole concept of the floor being a heat sink doesn't it?


Offline TXCraig1

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #31 on: September 17, 2013, 11:30:43 AM »
I guess this forgoes the whole concept of the floor being a heat sink doesn't it?

Conductivity works the same way in both directions regardless of material.
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Offline Tscarborough

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #32 on: September 17, 2013, 12:33:08 PM »
That is true, but for the purpose of a floor you also need mass, i.e. density, so the answer is, No, you do not want to use insulating bricks for the floor.  Aside from the fact that they are friable, they do not have enough density to act as a heat sink.

Online sub

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #33 on: September 17, 2013, 02:40:20 PM »
But these are in the dome, he is using Biscotto for the floor.  The conductivity of the dome is irrelevant since it doesn't transfer heat to the pizza by conduction.

Yeah, my bad I've read too quickly  :-[

I don't know who else you can contact for the biscotto, I'll try to ask on italians forums.

Alfa refrattari Tavellone Rosso 50X50X5 are used by some members.


Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #34 on: September 17, 2013, 04:00:03 PM »
I don't know who else you can contact for the biscotto

http://www.aversaforni.it/

Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #35 on: September 17, 2013, 05:42:03 PM »
Great find Nachtwacht.  Wanneer vertrekken we? ;)

Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #36 on: September 18, 2013, 01:50:04 AM »
Great find Nachtwacht.  Wanneer vertrekken we? ;)

It's half way Italy. I was thinking about holiday there next year but buying together it might be intresting to have them shipped over. No idea how expensive they are, I unfortunatly do not speak Italian.

Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #37 on: September 18, 2013, 03:12:06 AM »
I can't wait till next year, the oven has to be finished by Milan- San Remo 'cause I already promised my friends a pizza party. :chef:

Either way, I've called and mailed around, I asked my le panyol dealer for for info on their conductivity hoping I could just buy the floor tiles, he should get back to me, but I don't really have high hopes on that.

Than I found these http://www.acrivi.com/fr/6-pierre-a-pizza-pour-pizzerias through gsans thread.
This http://www.acrivi.com/fr/pierre-a-pizza-pour-pizzerias/171-radiant-pierre-refractaire-dalle-a-pizza-pour-four-pro-morice.html looks promising, composition is refractory material, quartz and volcanic rock, and it's reinforced.
I'll keep you guys posted.

Online sub

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #38 on: September 18, 2013, 04:12:31 AM »
Hi Christian,

Izzo Forni uses biscotto di Sorrento in their ovens.

Try to send an email  info@izzoforni.it

Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #39 on: September 18, 2013, 04:16:59 AM »
http://www.fydrofire.com/_fydrofire/index.php/technical-data

Dutch company making specialized professional baking stones. Have not contacted them about the costs but their thermal conductivity, wich is what you are looking most at, is good. If my normal floor fails (in the process of making it now) I will put one of those on top was my plan. (or the Italian one....)

Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #40 on: September 18, 2013, 05:34:05 AM »
Nachtwacht, it says
Quote
Thermal conductivity 1,0 x 10-5 m/mK
on their website, I gather that would be a bit high?

Sub, earlier you posted the link to aversaforni who seem to be the manufacturers of biscotto, is Izzoforni a different manufacturer or is their another reason to pass through them?

BTW: here's how far I am right now:

Online sub

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #41 on: September 18, 2013, 06:29:39 AM »
Sub, earlier you posted the link to aversaforni who seem to be the manufacturers of biscotto, is Izzoforni a different manufacturer or is their another reason to pass through them?


I don't know if they manufacture themself, but from what Marco Parente says, it might be difficult to buy it from them, there are only two artisan producers, I don't know the other one.

Finally, please note that by direct observation, owner comments, and most importantly suppliers direct info, many of these people above do not use the Biscotto di Sorrento (used at Forno Napoletano) which cost 8 times more of the cheaper alternatives, and does indeed have unique properties, however is produced in such low quantities and with Long ead times that is impossible to produce hundreds of ovens in a year or two.

Maybe try to ask the oven builders, after a few years the biscotto must be replaced, I do not know how it goes if you are abroad.

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« Last Edit: September 18, 2013, 07:15:09 AM by sub »


Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #42 on: September 18, 2013, 12:00:51 PM »
Nachtwacht, it says  on their website, I gather that would be a bit high?

It's lower than any firebrick we are able to find here in Europe (read Belgium and Holland, since shipping that stuff from Italy or any place is somewhat expensive because of the weight) wich are tipicaly something like 1.2 and up.

You do have some work to do on your oven I see. Should not be a problem to get it finished by next year though if you put some work in it. Yesterday I was roughly at the same place you were... I hope to finish it by this weekend. Will work for 3 full days on it... For now I settled on a normal firebrick floor because I have to be backing pizza in exactly 1 month time :)

Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #43 on: September 26, 2013, 02:50:32 AM »
So Nachtwacht, is it finished?

Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #44 on: September 26, 2013, 03:38:24 AM »
Depends on the defenition of finished :)

We arrived at the current state on monday. It is drying now, I will start some small fires during the weekend. I am thinking about how I am going to do the flue at the moment, it will be "free standing" with a heathbreak so I can build that against the oven later.

In this state, I just have to throw some ceramic blankets on it and I am able to make some pizza so in a way.... it is finished :) I plan to realy finish it after it is fully dried out.


Offline stonecutter

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #45 on: September 26, 2013, 08:38:10 AM »
Looking good!
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Offline nachtwacht

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #46 on: September 26, 2013, 08:59:04 AM »

Offline ChristianVerschaeren

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Re: Are these the right bricks for my Neopolitan oven?
« Reply #47 on: September 27, 2013, 10:03:35 AM »
Awesome!