Rustic Primitive Materials

[UtahBeehiver]

Re: Rustic Primitive Materials

Ann,
Been following your build from day one. Those oars might good bread peels. I think Tu made some long and narrow peels for bread. Here is a link to Tu's bread peels he made. Looks like the oars can work perfect.

http://www.fornobravo.com/forum/8/40...tml#post140559

[TropicalCoasting]

Re: Rustic Primitive Materials

Just wondering though... has anyone ever used the lava rock under their oven? I have an offer of a few big bags of the small rock for free if I wish to use it... any experience/ideas about this?

We didn't get an answer on this

Im assuming its got trapped air in it and it wont melt that it would work as insulation

[wotavidone]

Re: Rustic Primitive Materials

I used lava rock. We call it scoria, it's the reddish brownish aerated rock. I found an academic paper that said a mix of 3 parts scoria as large aggregate, 2 parts sand and one part portland cement had enough insulating properties to properly qualify as an insulating concrete. I reckon the mix I used had a thermal conductivity of about 0.25 W m-1 K-1. The paper gives all the mix components by weight, I had a lash at working that back to volumes based on bulk densities, and decided 3 parts scoria, weighed a bit less than 2 parts sand, and I part cement weighed a bit more than 3 parts scoria and nearly as much as 2 parts sand, so I reckoned I'd end up with mix B1 in the attached paper.
Not as good as vermicrete, but way better than ordinary concrete.
That mix has an MPa of over 20. That is over 3000 PSI, well and truly strong enough for a slab to hold up an oven.
I stood my sailor course of bricks straight on this slab. I put a 2 inch layer of vermicrete inside the ring of bricks, then put my floor bricks on that.
So my floor bricks sit on 5 inches of insulation, my dome sits on 3 inches of insulation.
And yes, it is full of holes even after you mix it into concrete. The second photo some aggregate I took out of my cement mixer and broke open to see whether the sand and cement paste had clogged the pores of the volcanic rock. the answer is no.

[Laurentius]

Re: Rustic Primitive Materials

Hi Annie,

If you mean, starting the oven wall outside of the perlcrete layer, that is the same as having no insulation! The heat from the oven will sink into the stone structure, its suggested that you expand your perlcrete, so that your walls are insulated. Excuse me if I misread your meaning.

[Laurentius]

Re: Rustic Primitive Materials

Annie,

I wouldn't worry about it or do the additional work, I think all is well.

[Wiley]

Re: Rustic Primitive Materials

Annie, My first post on your thread although I have read and followed for some time.

Good looking cat, is that a Maine Coon?

The edge of your insulating layer will be weaker but more important the edge will allow water to enter. The insulating layer will act as a sponge, a band or belt of concrete around the insulating slab would be better. A simple form would make the job easy (chasing members so you do not have to cut wood). Including a piece of rebar would be great and give the belt some resistance to cracking especially in the corners. Lacking rebar you could use barbed wire which might be more easily formed and available.

I would not suggest modifying an oar for a peel unless you have an extra oar from a broken pair. Easy enough to cut a small plank down. Here's a photo of what I mean:
http://www.fornobravo.com/forum/f11/...html#post74004

Your location lists Pacific Northwest. I too live in the Pacific Northwest on the Olympic Peninsula (on the Puget Sound side just south of Port Townsend).
Bests,
Wiley

[Laurentius]

Re: Rustic Primitive Materials

Sailors, EAT! Will that suffice?

[cobblerdave]

Re: Rustic Primitive Materials

Gudday Annie
Sorry for any probs with this post I'm using an I phone as the powers off and on at the moment. Where just getting the tail end of a cyclone here that's been down the coast. No worries here were on the lee of a hill higher than any flood and protected from the wind.....anyway.
You said in a previous post that were sorry not to have set you pearlcrete layer in a brick edge. Sorry for the misunderstanding that "plan" was not a diffinitive thing it was a lot of achievable sort of goals ( I thought) because at the time you were stuck firmly in the petty details and was losing the end goal. a working oven. But as a definitive plan its not ,but more a base line you could change at will.
Well you've got that soft pearlcrete edge don't worry about it yet I'm sure it will stand up to the rigors of your building for now. Leave the finish till the end. You could cement it and cover it with another finish. You could brick it now and see what it suits at the end. Or perhaps leave it for now and finish it at the end. Tiles mosaic ? Brick? Lime render ? Polished stone from the beach?
The neighbors arrive to share the storm. They have power but no beer it seems....better break out the chips and dips

Regards Dave

[Laurentius]

Re: Rustic Primitive Materials

Annie,

I really don't think that aluminum dryer vent pipe can withstand the heat from your oven, nor do I think that drain tiles are fired at a high enough temperature to keep them from thermal shock.

[Laurentius]

Re: Rustic Primitive Materials

No, the floor pattern is a matter of choice, like everything else concerning your build. The herringbone pattern is popular because your peel doesn't nick the edge of the brick when sliding in your pizza and it looks classy. Dome on or off firebrick hearth, the same. Some think that they might have to replace a brick or two in the future and the effort will be easier. My mom, used to say: "Six in one hand, half a dozen in the other, still adds up to be twelve".

[Laurentius]

Re: Rustic Primitive Materials

Hi Annie,

I'm here with you until the bitter end! I want to be here when you pull that first loaf of bread out of your oven and yell, "Hot dog, I did it", only to become obsessed in the pursuit of the perfect loaf. I have my reasons, I want others to suffer as I have suffered! No, really , I think that you will use your oven more that most and be very happy with it by building it right. As for the clay mix some and give it a test run.

[Tscarborough]

Re: Rustic Primitive Materials

Blue clay is usually bentonite. Are you in a volcanic area?

[Gulf]

Re: Rustic Primitive Materials

Tscarborough,
I am familuar with the term bentonite. It is what we called "jell" in the oil patch some years ago. Over here in SE Mississppi, we have varied colors of clay. One of which is a light colored blue. Most are red to a pink color. The blue clay that we have is not very close to the dark color of bentonite. I was just wondering if what Annie M. is referring to is close to what we have.
Before I started my build, this type clay was going to be my "go to" for a earthen/cob type oven. Do you think that it would have been acceptable?

[Tscarborough]

Re: Rustic Primitive Materials

Depends. If it is volcanic in origin, yes, if not probably not for the same reasons you used it in the oilfield.

[Tscarborough]

Re: Rustic Primitive Materials

Some types of bentonite swell when wet, they are used to line ponds and in the oilfield for that reason (That is not the only reason they are used in drilling mud though). Volcanic bentonite (K-bentonite) doesn't as much, so it should fine fine as far as I know.