Rustic Primitive Materials

[wotavidone]

Re: Rustic Primitive Materials

Annie, If cob is all the rage in your area, get the gang around and have a cob oven building weekend. From what I've heard and read, a cob oven can materialise that quickly.
Then you will have somewhere to cook, while you get organised to build a flash whacko fully insulated brick oven.

I was hoping that the more experienced oven builders on the forum might have added their opinons about the floor thickness by now. Don't make your decision just on my comments, please.
Regards,
Mick

[david s]

Re: Rustic Primitive Materials

I think one layer of bricks for the floor is plenty, especially if you also intend to use the steel plate under it. Two layers will take ages to get to temp. Can't be sure about the steel buckling from the heat, but I would think that because it is not getting direct flame impingement and the heat source is further away, it should be ok. I have seen plenty of 1/4" barbeque plates that have buckled, but I don't think a 1/2" one moves a bit. I've never heard of anyone trying a steel plate under the floor before so can't be sure how it would work, but an old Italian trick to increase thermal mass to extend cooking time, for certain cooking applications, was to throw in a couple of truck axles. This would reduce cooking area drastically of course, a problem your idea overcomes.

[brickie in oz]

Re: Rustic Primitive Materials

I think you will be sorry if you put that scrap iron under the floor, it will move and twist from the heat, its already cracked.
One layer of brick is fine unless you are building a bake house.

[azatty]

Re: Rustic Primitive Materials

Cut down the cast iron for the oven door, and then use the rest to build a brazier near the oven for grilling.

[brickie in oz]

Re: I am sooooo stubborn!

Annie... who has managed to capture wild yeast!!!

I caught some wild yeast years ago when I went to the top end of Queensland, had to get some ointment to get rid of it.

[mrchipster]

Re: Rustic Primitive Materials

You will want to use a running bond in the dome to increase its strength.
If you look at a traditional brick wall it is a running bond where the bricks are staggered.

Chip

[Tscarborough]

Re: Rustic Primitive Materials

That looks very nice, but it is still a flexible surface and you will need an inflexible surface for your oven. As you appear to have some batter to your wall, you will probably also want to cantilever the entry out over the wall a bit so you will not have to lean over to work the oven.

[mrchipster]

Re: Rustic Primitive Materials

I am sure the foundation you have provided will drain well but I think a water proof barrier between the foundation and the hearth slab may also be a good idea, someting as simple as a piece of sheet metal would do the trick. Water may wick up through the foundation you made and cause problems with heating without some form of barrier.

Chip

[Laurentius]

Re: Rustic Primitive Materials

Hi Annie,

Glad to hear that you are still around, taking your time. Hang in there. Cooked our turkey, dressing and bread in my over, tomorrow cinnamon buns and rye bread.

[cobblerdave]

Re: Rustic Primitive Materials

Gdday Annie
I wouldn't put away you plans for a dome oven just yet. Yes there a plenty of Really impressive ovens with the brickwork fitting together like a puzzle and whilst you have got to admire the workmanship you can build a good dome oven a bit more simply.
I used 1/2 and 1/4 bricks to build my own oven and they were cut with a simple brick bulster and the fancy cuts with a inexpensive angle grinder and diamond blade. Yes you end up with some larger gapes in the brickwork but it still works the same.
Heres a simple plan for you to consider.
Run a level row of bricks around the top of your stand. Fill with concrete this will give you a 3 1/2 in top. add some scrap steel if you want for extra strenght.
Run another ring of bricks ( leave a couple of weap holes just in case) fill with "pearlcrete". Thats your base insulation taken care of.
Lay a layer of brick to form the hearth.
Build a brick arch for your entrance leaving the formwork in place for the moment.
Now a ring of brick in the shape of your oven mortar the edges not the bottoms (the dome needs to be able to expand separate to the hearth).
Now fill the space in the middle with wet sand or soil and shape it into the dome shape you need. A simple stick through the middle to check the height.
When your satisfied with the shape, cover with plastic or layers of wet newspaper to stop the morter from sticking to the soil.
Now brick it up with 1/2 bricks layer by layer till near the top you'll need some smaller say1/4 brick sizes. Yes use the poor mans mortar mix.
Leave to set for a couple of days, remove the entrance formwork and dig out your sand formwork. ( a good trick is to include some empty softdrink bottles in the sand form, less soil to dig out)
Of course you'll have to use that lovely cast door somewere in here and you have inslate the dome, a cover over that, entrance, chimney etc but first thing first.
Anyway hope something in here helps

Regards Dave

[cobblerdave]

Re: Rustic Primitive Materials

Gudday Annie
Sorry but I do have labour on the point of insulation. Sand is not an insulator. . Your little domestic oven has little mass so not much wood is needed to keep the temperature but let that fire go out and it cools rapidly.
With a wood fired like your planning to build has a larger mass but once that mass is heated And is insulated from its surounds it keeps its heat for days.
Days for you to cook with.
Dont insulate and you'll be shovelling in wood and heating up the stand and the surounds. Stop shovelling wood the heat will still be going into the stand and your oven will cool rapidly.
You might have heaps a wood avaliable but it has to be sourced, transported, cut and shovelled into your oven. That alone is a burden, better time is spent cooking.
Pearlite is cheap sourced from local garden suppliers/ hydroponics supppliers etc. Mix with cement at 1- 5 it will insulate you hearth. Mixed 10-1 will insulate the dome.
Again sorry for labouring on this point....but you'll spend as much effort and time building a poor oven as a good one so you may as well get insulation right the first time.

Regards Dave

[Tscarborough]

Re: Rustic Primitive Materials

Exactly. An appropriate thermal mass isolated from the environment and insulated to the maximum extent allowed by space and finance. Efficient and easy to use, as well as being extremely environmental friendly. Doing it right costs less than redoing it.

[Tscarborough]

Re: Rustic Primitive Materials

You don't need much, a typical oven is only going to exert a dozen or so PSI on the slab, so it can be thin and uncomplicated, but you need an inflexible base for the oven itself. The slab will float on the insulation on the base, and any movement will be absorbed by it, not your oven.

[Laurentius]

Re: Rustic Primitive Materials

You don't need much, a typical oven is only going to exert a dozen or so PSI on the slab, so it can be thin and uncomplicated, but you need an inflexible base for the oven itself. The slab will float on the insulation on the base, and any movement will be absorbed by it, not your oven.

Insulation on slab, right? Fingers faster than brain or the other way around?

[Tscarborough]

Re: Rustic Primitive Materials

Yes, you are right.