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Author Topic: Why not use insulating firebrick anyway?  (Read 711 times)

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Offline ChristianVerschaeren

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Why not use insulating firebrick anyway?
« on: May 01, 2018, 02:48:23 PM »
Just a question that's been bugging me for a while.
I can see why a bread oven needs to be build with firebricks that store heat: you use fire to heat the bricks, take out the ashes and bake with the retained heat stored in the bricks.

But pizza ovens you're baking with the fire raging. So why not use bricks that aborb heat anyway, but keep it concentrated at the surface rather than migrate it to the outer edge of the thermal mass?

For an oven that's used daily, I can see why use heat-storing bricks. But one's that used weekly, wouldn't it make more sense to use insulating firebrick?

Offline Elkaybay

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Re: Why not use insulating firebrick anyway?
« Reply #1 on: May 02, 2018, 08:02:00 AM »
Hi Christian,

My pizza are always much better looking once the oven is fully saturated in heat than when it's in the heating phase.

I believe it's better to rely on a fully saturated oven and a good base of heat coming from all sides + a medium flame, rather than a huge flame as the only source of heat.

PS: my oven is fired every day and never goes below 300C so I might be biased.

Just a question that's been bugging me for a while.
I can see why a bread oven needs to be build with firebricks that store heat: you use fire to heat the bricks, take out the ashes and bake with the retained heat stored in the bricks.

But pizza ovens you're baking with the fire raging. So why not use bricks that aborb heat anyway, but keep it concentrated at the surface rather than migrate it to the outer edge of the thermal mass?

For an oven that's used daily, I can see why use heat-storing bricks. But one's that used weekly, wouldn't it make more sense to use insulating firebrick?

Offline Tscarborough

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Re: Why not use insulating firebrick anyway?
« Reply #2 on: May 02, 2018, 02:42:56 PM »
1. They are expensive
2. They are fragile.
3. They are extremely porous.
4. They  have low thermal conductivity (.17-.04 depending upon which one, VS .657 for WG low duty).
5. It is not what they are designed for, period.

Offline ChristianVerschaeren

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Re: Why not use insulating firebrick anyway?
« Reply #3 on: May 02, 2018, 05:09:45 PM »
Hi Christian,

My pizza are always much better looking once the oven is fully saturated in heat than when it's in the heating phase.

I believe it's better to rely on a fully saturated oven and a good base of heat coming from all sides + a medium flame, rather than a huge flame as the only source of heat.

PS: my oven is fired every day and never goes below 300C so I might be biased.

My point exactly, your oven only starts radiating back heat after it's saturated, with insulating brick it'll start radiating back right away.

Where's your restaurant, I'm in Leuven?

Offline ChristianVerschaeren

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Re: Why not use insulating firebrick anyway?
« Reply #4 on: May 02, 2018, 05:13:10 PM »
1. They are expensive
2. They are fragile.
3. They are extremely porous.
4. They  have low thermal conductivity (.17-.04 depending upon which one, VS .657 for WG low duty).
5. It is not what they are designed for, period.

1, 2 & 3 are not even true, or not always.
4: so?
5: Trees are not designed to heat up pizza ovens, they do a damn good job at it though.

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Offline spaddl

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Re: Why not use insulating firebrick anyway?
« Reply #5 on: May 02, 2018, 05:22:57 PM »
im trying to understand the hole material choices for the hearth ovens, but have some problems understanding what exactly the expressions mean. Whicht material are those fire bricks exactly ? (im from germany, and we dont have any of these words, mostly named by material, like chamotte)

Offline vtsteve

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Re: Why not use insulating firebrick anyway?
« Reply #6 on: May 03, 2018, 12:21:24 AM »
1, 2 & 3 are not even true, or not always.
4: so?
5: Trees are not designed to heat up pizza ovens, they do a damn good job at it though.

Well, I guess you schooled us!  Why bother asking? I was going to reply (agree w/Tom), but I'm done. You're ignored.
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Offline Elkaybay

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Re: Why not use insulating firebrick anyway?
« Reply #7 on: May 03, 2018, 05:06:15 AM »
Hi Christian, are you sure that they'd start radiating right away?

My restaurant is in Hanoi, Vietnam  ;D
Do you happen to know Pizzeria di Fiore in Tervuren? I learned with the owner there. It's my favorite pizza place in Belgium, even if it doesn't qualify as Neapolitan.

My point exactly, your oven only starts radiating back heat after it's saturated, with insulating brick it'll start radiating back right away.

Where's your restaurant, I'm in Leuven?

Offline ChristianVerschaeren

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Re: Why not use insulating firebrick anyway?
« Reply #8 on: May 03, 2018, 09:38:33 AM »
Well, I guess you schooled us!  Why bother asking? I was going to reply (agree w/Tom), but I'm done. You're ignored.

The message board alpha-male and henchmen trying to get on his good side, you see it every time.  :-D

Why bother asking is a good question though, which I'll try to answer.

Over the years we've been pretty good at dissecting how the pros from Napels build their oven, those guys are not into the whole 'information needs to be free' thing and weren't sharing their secrets, so there's been some interesting discussions and sleuthing.

And we collectively figured out how to build a traditional Neapolitan restaurant oven. Thing is those are built for restaurants, which probably have a different spec sheet than a backyard pizza oven has that's only used weekly.

And that is what most of us here are building.

So I'm trying to figure out, now that what we know what the traditional way of doing thing is, what might be a better way of doing things, more adapted to weekend-warrior pizzaiolos.

The main thing, obviously is that professional pizza ovens never cool down, while backyard ones do. So I'm looking for a way to build a pizza oven that doesn't need a whole day to get up to temp.

And I'm thinking insulating firebrick might be an idea worth exploring.

I'm basing this on the experience I gained building a french geulard oven that uses insulating firebrick in the "foyer". Basically the little chamber under the oven where the wood is burned, kind of like a rocket stove, so it can spew a long hot flame into the baking chamber.
The reason they used insulating firebrick there is to concentrate the heat to get better combustion, not to store it.

Anyway, I see parallels there with a pizza oven.
So I'm thinking it could be done, but I'd rather learn about oversights I might have had that make this a %$# idea, rather than find out the hard way.

 "that's not how the Italians do it /  that's not what 'they're made for /  that's just how it is." are not oversights, I know all that, still curious about what the perfect backyard pizza oven would look like. Wasn't Shuboye onto one of these quests at one time, whatever happened to that?
 




Offline ChristianVerschaeren

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Re: Why not use insulating firebrick anyway?
« Reply #9 on: May 03, 2018, 09:40:32 AM »
Hi Christian, are you sure that they'd start radiating right away?

My restaurant is in Hanoi, Vietnam  ;D
Do you happen to know Pizzeria di Fiore in Tervuren? I learned with the owner there. It's my favorite pizza place in Belgium, even if it doesn't qualify as Neapolitan.

No, I'm not sure, from what I gather they're built to concentrate heat in the chamber, so I guess that's what they do more so that regular firebricks.

Ha! Won't be visiting anytime soon then, but I've been to the Tervuren one. I walked in, the guy was on his phone for 10 minutes ignoring me, finally fed up I walked back out  ::)
« Last Edit: May 03, 2018, 09:44:23 AM by ChristianVerschaeren »

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Offline Tscarborough

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Re: Why not use insulating firebrick anyway?
« Reply #10 on: May 03, 2018, 09:45:34 AM »
To begin with, the Italians do not build home ovens, they build commercial ovens.  Ask Craig how long he fires before cooking, VS the 2 hours I spend.  If you are building a commercial oven, then you could use the IFB for the second layer but not the first.  They are so friable they would not last a year in a commercial oven, and they would not last a day as the floor.  If you do not think thermal conductivity has anything to do with it, you are probably going to need to do some more practical experimentation.  I say go for it: build one and post your results.

Offline TXCraig1

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Re: Why not use insulating firebrick anyway?
« Reply #11 on: May 03, 2018, 09:56:19 AM »
I don't know anything about IFB, however your underlying concept is absolutely correct. I have examples of both ends of the spectrum in my Garage: my Acunto and my Pizza Party. The Acunto takes a day to heat (and really two days before it starts nearing it's optimum performance), and the PP takes 17 minutes. Both bake a near identical pie.
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Offline Rick_F

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Re: Why not use insulating firebrick anyway?
« Reply #12 on: May 03, 2018, 11:18:46 AM »
It might work for the dome, but for the floor, you may want some mass for heat storage with a bit more conductivity or you may risk under-cooked bottoms.  Traditional materials both reflect and radiate heat, and the steel in the pizza party reflects the heat even better.  Most insulating materials are not necessarily good at reflecting heat, they just slow down the transfer of it. 

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