First WFO build

[swarm1023]

The brick I'm using has never been used in a kiln. It was extra brick for an old kiln that was decommissioned. If it were used bricks, it would depend on what part of the kiln it came from. The front, preheat section is where everything is burnt out of the kiln and could potentially have some bad stuff, but in the main heating section there would be nothing left worry about.

[Akamicko]

I work at a ceramic tile manufacturer and have been given some kiln brick from a kiln that was taken out of service and am planning to build with it.

Any concerns about toxic / harmful material that may be present in the used kiln bricks as a result of the ceramic manufacturing process? Just a thought.

[cobblerdave]

Re: First WFO build

G'day
The configuration of the Forno oven ( the mass V insulation) makes it a perfect weekender. If it's a Pompeii or a vaulted arch ( like tzcars) it doesn't matter.
You can heat and cook pizza in about about and hour to and hour and 1/2. As long as you keep an active flame to replenish the heat almost continuous .Cap off with an insulated door and you have heat to bake bread, roast, and finally low and slow cook.
Time to have a full read of the Forno plans it's not just plans it's the whys and wherefores of mass and insulation. 101 pages from memory. Well worth the read
Regards dave

[swarm1023]

Re: First WFO build

Well, that's what go me thinking I could do this, the vast majority of the time its just my wife and kids. The dough recipe I use makes 3 pizzas. Occasionally when we have friends over I'll make more, but about 12-15 is the most I've done at a time.

[Tscarborough]

Re: First WFO build

It all depends upon your intended use. 2 or 3 pizzas at a time? 10-20? 100s?!

[swarm1023]

Re: First WFO build

OK, somebody tell me if I'm going from one extreme to the other, my first thought was to use a full 9" brick for my dome walls, which sounds like it would be too much to ever heat up. So then I decided to cut the brick in half. Now, however, I'm wondering if I could cut the brick down to 3", put 2" of ceramic fiber blanket, and then cover with 3" or 4" of lightweight, insulating concrete. Any thoughts?

[swarm1023]

Re: First WFO build

ok, more to think about.

[mrchipster]

Re: First WFO build

well my original thought was to stand the bricks on there sides, see pic, but I thought by stacking the brick it might actually help to insulate by allowing the bottom layer of bricks to act as an insulating layer.

yeah, the wood is kiln dried and works great, I've used a lot of it in my smoker.

Dense Firebrick is not an insulator and a 4 inch thick floor will be very difficult to get hot. But better than your layering idea.

The space between the two bricks will limit your transfer of heat from the top brick to the lower brick. the layered brick approach will give you the worst of both thin floor with minimal thermal mass and a heat sink that is taking heat away from your floor but not allowing efficient transfer of the heat back into the oven.

You will be wicking heat away and because of the minimal air space between the bricks you will waste significant energy getting the heat into and out of the lower bricks. The air gap acts as a thermal break but radiant heat will still be lost to the brick you will just loose a great deal of conductive heat.

In order of effectiveness as an insulator. Air is the biggest insulator in this analysis but only when not allowed to move thus the air trapped in the small cavities of the insulation.

Ceramic fiber
Foamglas
Insulating fire brick
Perlite
Vermiculite
Perlcrete or vermicrete
Sand/glass
Firebrick

[swarm1023]

Re: First WFO build

well my original thought was to stand the bricks on there sides, see pic, but I thought by stacking the brick it might actually help to insulate by allowing the bottom layer of bricks to act as an insulating layer.

yeah, the wood is kiln dried and works great, I've used a lot of it in my smoker.

[mrchipster]

Re: First WFO build

I know it might be hard to do but I would buy brick for the floor. The reduced thermal transfer and difficulty in getting a smooth floor using tapered bricks will make it well worth the extra money for proper floor bricks.

That is almost free wood and if it is kiln dried it is better than free.

[swarm1023]

Re: First WFO build

I'm planning on stacking the brick for the floor, turning pieces in opposite directions to have a flat cooking surface.

Not exactly free wood, but there is a hickory mill here that will sell their left over pieces for $10 for a pickup truck load.

Starting to think I'll cut the brick in half.

[mrchipster]

Re: First WFO build

4.5 inch thick dome is a lot and 9 inch will take a long time to heat up and use significant amounts of wood. If you do decide to go the full 9 inches, how thick and what type of brick do you want to use on the floor?

I hope you have free wood available.

[swarm1023]

Re: First WFO build

Well, that's kinda been my concern, didn't know if anybody else had had any issues trying to use a full size brick. I'm gonna have to think about this a little more.

[Gulf]

Re: First WFO build

9" thick! Wow. Mexman, just tore an 8" one down and started over because of long heat up times . But, that is your choice.

[swarm1023]

Re: First WFO build

No, planning on leaving them full size. I'm afraid it will take longer to heat up, but on the flip side of that it should hold temp a lot better and longer.
I can get high heat clay for practically nothing so I'm going to fill the big gaps at the back side of the bricks with basically a high temp cob similar to what people use to make ovens with.