Concrete recipe for Weber mod?

[scott123]

Hank and Adam, I don't think Jeff could spell it out any clearer.  This design, as it stands, is not viable.  You're either talking heat from below, with the top of the pizza never getting properly baked or you're talking heat source on the side, which results in an 8" or smaller pizza.

If you guys want to make 8" pizzas, go for it, but, if you want to save yourself a lot of angst, use your webber and build an LBE. Getting a Neapolitan pizza out of an LBE is no easy task, but it's got a much better track record than this. At least with an LBE, you've got a fighting chance.

[akuban]

Thanks for the advice, Scott. On that note, LBE does seem like the way to go. I have been lured by the pizzaforge's wood fuel, but LBE sounds more viable -- and easier to hack in a weekend's time. As always, you are a font of pizzawisdom. Chars!

[toddster63]

I had wished meatboy success, and hoped he would post some of his efforts, but he and his "FrankenWeber" have seemed to vanish...

His idea is very doo-able. We have the Pizzahacker here in the 'Frisco bay area; the Hacker cooks 10" or so Neopolitan pizzas in his 22.5" Frankenweber, with the perlite-cement sides and dome. He has great reviews on Yelp, and a following on Twitter that show up where he is on certain nights. You can see some videos of him on his site HERE.

I've been in line for his pizzas, half a block, 45 minute wait (but while they were good, my LBE pies are better...!)

[siouxerbrewer]

I know I'm late to the conversation but I'm a newbie to this forum and pizza making in general.  That being said the "Frankenweber" or "Pizza Forge" is what sparked my interest in pizza making.  I have scoured the forums to see how to build one of these things and I THINK I might have found the missing ingredient to the Perlcrete mixture and that is AIR ENTRAINMENT.  One of the main problems I keep reading about is that the when attempting to build a frankenweber the concrete is too heavy, it is not insulated enough, and requires too much refractory concrete for the relatively small build.  Also, in one of the "Pizzahacker" videos he mentions that the dome looks heavy but is light.  I believe that by introducing air into the Perlcrete (Refractory concrete and perlite) it increases the volume of the mixture without increasing the weight AND it adds strength and insulation.

http://www.australianperlite.com/perlite-concrete.htm (Perlecrete mixing guid)
http://www.fornobravo.com/forum/f6/deviant-design-6652.html (a possible recipe for Perlecrete with an air entrainment agent)

Very nice molding job meatboy!

[scott123]

SB, perlite is basically stone popcorn.  It's almost all air.  Perlcrete contains loads of air.  This is what makes it so light.  It's this lightness that makes it an especially poor material for an oven, because it can't store and radiate back heat.

Pizzahacker has been through many oven permutations, and, honestly, I don't know what he's doing now.  I do know that he's making some amazing pizza, but, unless someone knows exactly what his present oven setup is, I continue to view perlcrete as a losing battle.

[AimlessRyan]

SB, perlite is basically stone popcorn.  It's almost all air.  Perlcrete contains loads of air.  This is what makes it so light.  It's this lightness that makes it an especially poor material for an oven, because it can't store and radiate back heat.

So basically it's down?

[scott123]

Well, I wouldn't make a comforter out of it, but if there was a stone equivalent to feathers, it would be perlite.

[siouxerbrewer]

SB, perlite is basically stone popcorn.  It's almost all air.  Perlcrete contains loads of air.  This is what makes it so light.  It's this lightness that makes it an especially poor material for an oven, because it can't store and radiate back heat.

Pizzahacker has been through many oven permutations, and, honestly, I don't know what he's doing now.  I do know that he's making some amazing pizza, but, unless someone knows exactly what his present oven setup is, I continue to view perlcrete as a losing battle.

I can see that the quest for the "Pizzahacker Perlcrete" recipe has been a challenge for quite a few people.  I have never worked with concrete before but based on what I read in one of those links above there are different densities of Perlite and there must be a perfect blend to accomplish this goal.  I wonder if simply using enough refractory cement with enough air entrainment would eliminate the need for Perlite in this application.  I find it frustrating that so many people have tried unsuccessfully to mimic this. Is there Perlite in firebricks?

[Tscarborough]

Perlite is mostly air.  It is basically volcanic glass that is heated, and it puffs for the same reason popcorn does.  Man-made perlite is available in sheets and boards, called Foam-glass.  It is on the edge for woodfired ovens, but should work well for frankenweber type uses.

[Tscarborough]

Here is what you need to know for perlcrete, different uses use different ratios.  5-6 to 1 for under an oven all the way up to 12-1 for insulation over the top.

http://www.perlite.org/perlite_info/guides/lightweight_insulating_concrete/general/perlite_concrete.pdf

[siouxerbrewer]

Here is what you need to know for perlcrete, different uses use different ratios.  5-6 to 1 for under an oven all the way up to 12-1 for insulation over the top.

http://www.perlite.org/perlite_info/guides/lightweight_insulating_concrete/general/perlite_concrete.pdf

It seems that most people attempting to make this Perlcrete use a type of Perlite designed for garden use.  Those look like large chunks of Perlite; are there smaller chunks that might blend in better making for better structural support?  Also when you speak of mixtures is that Perlite:Refractory concrete mix or Perlite:Portland cement?  Here is a link to a guy who experiments with different mixtures for a rocket oven http://woodfiredpizza.org/Rocket/index.html  I wonder why nobody has seemed to crack this yet?

[Tscarborough]

Normally, perlite will be 1/4" and down with most passing sieve well below that.

[buceriasdon]

That is so cool that someone actually built a rocket oven! Too bad I didn't see any pictures of pizza baked in it. Thanks for the link.
Don

[shuboyje]

It seems that most people attempting to make this Perlcrete use a type of Perlite designed for garden use.  Those look like large chunks of Perlite; are there smaller chunks that might blend in better making for better structural support?  Also when you speak of mixtures is that Perlite:Refractory concrete mix or Perlite:Portland cement?  Here is a link to a guy who experiments with different mixtures for a rocket oven http://woodfiredpizza.org/Rocket/index.html  I wonder why nobody has seemed to crack this yet?

Because there's nothing to crack.  Perlite is an insulator, and mixed with Portland at the ratios already mentioned it works great.  No matter what you mix it with perlite is not a hot face and it does not have thermal mass.  I don't know why this topic always comes up. 

[siouxerbrewer]

Because there's nothing to crack.  Perlite is an insulator, and mixed with Portland at the ratios already mentioned it works great.  No matter what you mix it with perlite is not a hot face and it does not have thermal mass.  I don't know why this topic always comes up. 

I think this topic comes up frequently because as far as I can tell, nobody has been able to successfully replicate the Frankenweber. People's attempts at replication usually result in a lightweight oven that crumbles to pieces, or an extremely heavy, not so portable beast. The idea of a portable WFO is awesome esp when one lives in an apartment.

[shuboyje]

For many reasons I and others have explained many times a luggable wood fired oven isn't feasible in my opinion.  Gas makes much more sense because you do not lose oven space to the fire.  The lbe is a luggable gas fired high temperature pizza oven, so again, what is there to crack?  I'm not being a jerk, I just strongly feel these efforts are a waste of time.  Thezaman had an oven successfully built by a professional.  He found it doesn't work due to lack of mass.  It works great for a short time until the temperature plummets.

[buceriasdon]

http://backyardpizza.blogspot.mx/2011/03/frankenweber-is-in-full-on-construction.html
FWIW. Be sure and read comments.

[Tscarborough]

The problem is that you are trying to accomplish 2 seperate functions by a compromise. You need refractory mass and you need insulation. As a rule the two are mutually exclusive.

Also, refractory materials are inherently brittle and prone to failure at thicknesses under 3 inches. For a stationary unit 2" is doable but for a mobile unit more specialized and technically exact materials are needed.

Then you need a couple of inches of insulation and some sort of protective coating over that, since refractory insulation is both brittle and friable. 

Formwork needs to be slick and non-absobative, and must also be built so that it can be easily removable and possibly reusable.

In short, good luck with that. 

[shuboyje]

I've been thinking about this a lot today.  Instead of being negative and just telling you guys this won't work I've got something constructive to add.  Here is a simple design for a luggable oven that would work if you could deal with the space constraints:

1. Start with a water heater drain pan like this one:
http://www.lowes.com/pd_317905-11713-QP-28_0__?productId=3126917&Ntt=water+heater+pan&pl=1&currentURL=&facetInfo=

2. Use the pan as a base and cast a 4" layer of 6:1 perlcrete.  Maybe even add handles to the pan before casting the insulation layer.

3.  Get a round kiln shelf like this one:
http://www.axner.com/cordierite-shelf-21roundx34.aspx

Place the kiln shelf on top of the perlcrete centered.  This is now your ovens hearth.

4.  Form a dome from wire mesh 6" larger in diameter then the kiln shelf.  For the shelf above the dome would be 27" diameter.

5.  Using wire buttons attach 2" ceramic fiber insulating blanket to the inside of the wire dome.  Here are blankets and buttons:
http://www.axner.com/ceramic-fiber-buttons.aspx
http://www.axner.com/superwoolfiber-2thicksoldpersqft.aspx

6.  Inside of the ceramic fiber blanket form a 1" layer of dense castable refractory.  Something like KS4-V plus would work and can be obtained from any of these locations:
http://www.hwr.com

7.  Cover the outside of the dome with stucco over the wire mesh.

You now have a small lightweight low mass fully insulated pizza oven.  It should hit high temperature fast and easy with the proper balance of heat that bottom heat source ovens lack.  With a low enough dome(maybe in the 8" range) you might be able to get enough top heat with a small enough fire to cook a 12" pizza, but it would be tight.

Here is a crude drawing of the basic idea.


  

[Jet_deck]

Jeff, is the water heater pan galvanized?