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stormy 06-16-2008 11:24 AM

Native stone oven
 
I was camping last weekend and noticed a large rock fall along the road. It was a fine grain brown sandstone that was breaking into 4 in slabs. It was very smooth with many stones 3 or 4 feet across. Has any one made a oven from native stone?

jengineer 06-16-2008 12:37 PM

Re: Native stone oven
 
Interesting thought - no I don't think anyone has used sandstone before. Not sure what the thermal properites will be but I do know that you want to make sure the mosture content is near zero. Any moisture will turn to steam and steam takes up more volume than water and it will crack/spall and sometime explosively break up with shards being trown about. This for some reason is something that the folks at MHA forgot about earlier this year.

dmun 06-16-2008 02:06 PM

Re: Native stone oven
 
I used some bluestone from an abandoned quarry in Pennsylvania. It's a different stone, but still sedimentary. I found it difficult to cut, and it had an unfortunate tendency to split along the sedimentary lines. You should get a test piece and try cutting it before you plan to move a bunch of it home.

This was strictly for decorative masonry: I wouldn't use a natural stone for your dome or floor, unless it was something specifically heat friendly, like soapstone.

stormy 06-16-2008 11:01 PM

Re: Native stone oven
 
I was looking to put it together at the camping spot so the haulage is only a half mile or so. What about a steel top made from a one inch slab? I live in Northeast Ohio, we have access to steel in different shapes. Maybe cut a big pipe in half for the top? What if I plastered the inside with a fireclay morter, might that cut down on the spalding? We get 40 to 50 people on these camping trips so the heavy lifting is not an issue. Could I test the stone by building a fire on a slab and see if it cracks? I have seen river stone blow up because it has voids in it but the stone I am looking at is very fine grain and uniform in texture. It is used as a building stone here in Ohio, mostly facing .

dmun 06-17-2008 08:17 AM

Re: Native stone oven
 
All sedimentary stone that's been outside is full of water. It's porous. It will crack, or worse, if you apply heat to one side, just because of the trapped moisture. Without a careful and gradual heat curing process you aren't going to know about it's heat resistant properties.

asudavew 06-17-2008 08:48 AM

Re: Native stone oven
 
Is it sand stone?

I wouldn't want that in my pie.

As for a steel dome.. Someone around here is building one (already built one)
I'll see if I can find the thread.

asudavew 06-17-2008 08:52 AM

Re: Native stone oven
 
Here's the thread.

Pretty cool build!


http://www.fornobravo.com/forum/f3/s...oven-3717.html

stormy 06-17-2008 05:54 PM

Re: Native stone oven
 
The tank end looks like a better plan than pipe and there are a ton of them about. Thanks for the input.
AS to the stone, I'm going to blast some in our forge, 20 lb of charcoal and the blower, makes carbon steel soft in 10 min. It should be a good test of that stone.
There is a old blast furnace built out of a 2 foot thick seam of that brown sandstone in the general area where I am going to get the stone. The furnace was built before the Civil War and is still standing. The park system used the stone for picnic grills dating from the CCC. Many of them are still in use 70 years latter. I think it might be worth putting some real heat to that stone and see if it comes apart.

asudavew 06-17-2008 05:56 PM

Re: Native stone oven
 
I guess I'm thinking of sandstone from around my parts. (West Texas)
It's soft and any rubbing will easily knock sand particles off.

This should be interesting.
Let us know what you come up with.

stormy 06-17-2008 07:44 PM

Re: Native stone oven
 
They make a high quality grinding stone out of it here in Ohio. The Indians used it for grinding bones into spears and gouges. I found one in my corn field that had about ten egg cup shaped depressions in it of different radius. They call them cup stones.
I was looking at your cost sheet, an oven is not cheap. I wanted to go as cheap as I can and yet get a oven that will cook things over a long weekend on the river with the gang. I have burned some of the local clays in a gas kiln with shrinkage of 5 to15% at cone ten. The more organic types had the most shrinkage but were the lightest in color and weight when cooked. The clay with little or no oxidation had the least shrinkage but were more likely to crack. I was thinking of cob over the steel dome with a pad of steel wool to cover the expansion from the cooking fire. When they reline the local blast furnances they strip out all the lining and it goes to the slag yard where it is sold as fill. That stuff would make good frit. Clay, frit, portland , sand, and some sawdust might make a good heat sink for the cooking dome. Might even find some good bricks in the fill. Last time I bought it , it was $8 a ton at the yard. You can not use the slag as it blows up like a bomb when heated. The brick is good stuff for heat.


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