sand under firebricks?

[mrchipster]

Re: sand under firebricks?

Oh, one more thing, tell me if this is a dumb idea... I want to make a unique flue, but it won't be ready for a few months. Can I put a simple metal flue in and then just build the new one to slip around it? I'm a sculptor and can't do anything the ordinary way.... Wouldn't it be fun to make it a dragon blowing smoke or a gargoyle.? Or a woman's head and the smoke comes out her ears? Ha ha. I'd make out of terra cotta and glaze and fire it. Any suggestions on what it could be?

Sounds like a great idea.

As long as the inner flue is stainless this should not be a problem. I would not have the inner flue contact the outer decorative flue unless the inner is double wall. The stainless might expand and crack your outer decorative flue. If you did want to have some contact for positioning and stability I would have 3 contact points going in from the decorative so the stainless could flex but not exert undue pressure.

I like the dragon, or some other serpent like creature trying to escape the oven. The ears would have to be quite large to deal with the volume of smoke.

Chip

[Poetryart]

Re: sand under firebricks?

Oh, one more thing, tell me if this is a dumb idea... I want to make a unique flue, but it won't be ready for a few months. Can I put a simple metal flue in and then just build the new one to slip around it? I'm a sculptor and can't do anything the ordinary way.... Wouldn't it be fun to make it a dragon blowing smoke or a gargoyle.? Or a woman's head and the smoke comes out her ears? Ha ha. I'd make out of terra cotta and glaze and fire it. Any suggestions on what it could be?

[Poetryart]

Re: sand under firebricks?

Excellent! I'll get to work.
Next question: What happens if, after the dome is in, we surround the outside of the dome hearth with concrete to make the concrete under the hearth level with the dome floor? We haven't removed the wood form from pouring the hearth yet and could easily add to it. This would make everything nice and neat and easier for the decorative stone application. We're planning to stucco the dome after the fb blanket. There's a layer of concrete between the fb blanket and the stucco, too? Right? Hope this makes sense. :

[cobblerdave]

Re: sand under firebricks?

Gudday
Don't be.... you can do it either way and yu'll still get the slip between the dome and hearth. When I did mine the thinking was the first course sat at the side of the hearth so you were able the change hearthbricks if needed. Guess what no one seems to need to change hearthbricks so current practice is the dome sits on the hearth. Makes for less cutting of the hearth brick so thats good

Regards Dave

[Poetryart]

Re: sand under firebricks?

I'm installing the soldier course first thing in the morning, question: do I put it ON TOP of the hearth, or outside of it? In reading the various posts, I'm really confused, do I worry about expansion of the hearth floor cracking my dome, or, if it sits on top, will everything move independently? I borrowed a wet saw and am ready to go. Please help! Thanks!

[emsoven]

Re: sand under firebricks?

i used a layer of sand over my vermiculite floor cheep and works fine my floor is as flat as as my drive way there is no real need to use clay

[mrchipster]

Re: sand under firebricks?

Next question. The FB board arrived and it's a softer material than I expected. Do I : 1. cut it to fit the INSIDE of the pizza oven so that only the floor of the oven sets on it?
or: 2. let it overlap the 36" interior allowing the bricks for the dome to sit on it?
If it's #1, then do I cut the floor firebricks to fit the same foot print, putting the soldier course outside of it entirely?
Our hearth is only 54" by 60", will it be a problem to make it an inch or two closer to the back edge, so that I can have a bigger landing? That means that for about 3 or 4 inches across the back, the insulation layer of concrete will be slightly thinner that other places.
Thanks! ~ Shelley

All heated material needs to sit on the insulated board. And concrete is not insulating material so I am not sure what the insulating layer of concrete refers to.

Chip

[Poetryart]

Re: sand under firebricks?

Next question. The FB board arrived and it's a softer material than I expected. Do I : 1. cut it to fit the INSIDE of the pizza oven so that only the floor of the oven sets on it?
or: 2. let it overlap the 36" interior allowing the bricks for the dome to sit on it?
If it's #1, then do I cut the floor firebricks to fit the same foot print, putting the soldier course outside of it entirely?
Our hearth is only 54" by 60", will it be a problem to make it an inch or two closer to the back edge, so that I can have a bigger landing? That means that for about 3 or 4 inches across the back, the insulation layer of concrete will be slightly thinner that other places.
Thanks! ~ Shelley

[C5dad]

Re: sand under firebricks?

I am one of the guilty for using sand - I for one have not had any problems with it and feel it is serving me well. Reason I used it was the fact that getting bags of fire clay is a pain since very few here in the desert SW have fireplaces. I have to drive an hour to get a flu liner if the local masonry shop does not have them in stock.

CW

[david s]

Re: sand under firebricks?

My clay is a low fire terra cotta, so it won't work, I fire it at about cone 06. Does anyone ever just set the firebricks directly on the FB board? Can I put a layer of vermiculite down? Regular sand is probably not a good idea, as one really good fire could melt it into glass? I've melted bottles in my kiln before at 06.
I really appreciate the advice - I would have never attempted building a WFO before this website. If I get the refractory/ fireplace mortar I won't need the homebrew? Is that correct?

Just use your terra cotta clay, but crush it up to powder then mix it 50/50 with sand. an 06 cone is around 1000 C you won't get anywhere near that. To melt terra cotta you would have to fire it up to stoneware temps.You canpurchase the refractory mortar, but be careful, some of them only work when fired to much higher temps than your WFO will reach, so they are then ineffective. Best to use the homebrew IMO.

[cobblerdave]

Re: sand under firebricks?

David s
Again thanks for clearing things up... your a font of knowledge.
I think I have made a wrong asumption after reading that the slurry left with a bricksaw was a source of fireclay

Regards Dave

[david s]

Re: sand under firebricks?

Usually the mix for under the floor is a 50/50 sand, fireclay. This is only required to get the bricks level. Place them directly on the insulating board if you want. Do not be concerned about sand melting, it won't. It needs the presence of fluxes to lower it's melting point anyway and you are not adding any to the mix.

[Poetryart]

Re: sand under firebricks?

My clay is a low fire terra cotta, so it won't work, I fire it at about cone 06. Does anyone ever just set the firebricks directly on the FB board? Can I put a layer of vermiculite down? Regular sand is probably not a good idea, as one really good fire could melt it into glass? I've melted bottles in my kiln before at 06.
I really appreciate the advice - I would have never attempted building a WFO before this website. If I get the refractory/ fireplace mortar I won't need the homebrew? Is that correct?

[david s]

Re: sand under firebricks?

There's no way you will get near melting glass. That occurs at around 900C depending on the glass type, unless you throw in some small beer bottles some of which I'm told are partly plastic. They will melt in a fire. The surface of the oven crown may go over 573 C but not the rest of the oven.
I have fired clay many times in a campfire, directly in the coals. That is sufficient to fire the clay. The tricky part is to increase the temp slow enough not to crack the pots. Sometimes there are portions of the pots that did not get hot enough and you can wash the clay away there.

[Les]

Re: sand under firebricks?

David,

I may be off base but 573c is only 1063 f. If I am cooking at 750 - 800 f after I let it cool down, are you sure we don't hit that temp? My laser only goes to a few clicks below 1000 but it pegs every time I fire the oven. If I recall, I thought someone fired some clay a few years back in their oven. I only bring it up because sitting your brick in glass has got to be worse than mortar.