Clay outdoor bread oven??

[DennisK]

Thanks DennisK, I'll figure out some way to isolate the concrete blocks from the oven platform then. Maybe I'll set the steel plate in a bed of cob to dissipate more of the heat before it comes in contact with the concrete bricks. What percentage mix of cement and clay did you use for your bricks? The soil we found is almost 100% clay so any additives we put in to help it remain stable and last longer the better as far as I'm concerned. I don't want to go to all this work to have to take it all apart again and redo it next year. That would be depressing.

If you can line your firebox with a clay mixture, I imagine that would save the cinder blocks. I started out using the common concrete mix of 1 part cement to 5 parts of aggregate and sand, but then I read somewhere that that much cement is not necessary as the dirt has a lot finer grain than sand; so I doubled the dirt (aggregate) proportion without any compromise to the brick. I haven’t tested how little cement I could get away with yet, as my test would also involve soaking the brick in water for a month. That proportion will be dependent on the kind of earth you are using. I suspect the higher clay content, the less cement is required – my guess. I tested the earth I was using by filling a quart mason jar with saltwater, then adding about half with the soil. After letting it stand undisturbed for a day, I could clearly see the different layers of rock, sand, clay and silt. My clay content was at about 20%. This is border-line for CEBs which are strict earth bricks made by compression. My current interest is in CEBs, but I haven’t made any yet. What I have been making are what I call “mudcrete blocks” which is a simple earth, cement, water mixture poured into a mold. I am pleased with how they turn out, but it is difficult to design a mold that will release my brick before it cures without it breaking. I have been making some complex shapes which involve more corners and a greater opportunity for the product to fail during release. I am making my forms out of steel which is painted and then baked. If I don’t bake the paint, the “mudcrete” will actually peal the paint off the form when I pry it lose! As far as free hand molding the “mudcrete” onto a form like an outside oven, I have done something like that with good results. I made a wood burning stove from an old propane tank and I lined the inside bottom with about an inch of “mudcrete”. It worked quite well as the tank bottom never got very hot due to the insulation properties of the “mudcrete”. That is why I think the firebox lining with mud will serve you well.

 

[erinszoo]

Well here's what we did today!

Here's the test bricks after two days of drying in full sun. We flipped them over several times a day to make sure both sides could dry. However, if we do it again at some point, we will let them dry for a full three days as a couple of them weren't entirely dry in the center.


We took each brick, starting with the most sand added one and dropped them like this onto our concrete patio.


The first three (300%, a 200% that my husband made seperately, and the 150%) pretty much crumbled like this.


The next two (75-80% and 40-50%) broke cleanly into two pieces, and the last two (10% and 0%) didn't crack or chip at all. So we've decided that we are going to go with somewhere on the light side of a 25% blend of straight soil and sand for the inner layer that will be exposed to the most heat. Then we are going to use a 50% mix with straw added for the outer layers and then I'm going to use some straight clay soil for the decorations I'm planning since they will be the most exposed to the weather.

Thursday I'll get to buy my steel plate for the base of the oven and then hopefully over the weekend we can make another run to the river to load up our buckets with our soil of choice for this and I can start building.

I'm getting excited!!

 

[erinszoo]

My great grandfather was a brick mason and actually moved to Oklahoma during the land run to claim land he could use for making brick. He used a wooden form that they coated in a mix of lime and ash before they filled them with the mud, then they let them sit for a day in the molds, and then turned them out into the sun to dry. I don't know how you could use that with your steel forms though. Hmm? Now you've got me thinking ... you know they make a mold release of some kind for pouring concrete counter tops and such, I think. Of course when I did poured molds for sculptures we used vaseline to coat the molds before pouring. Sounds like you have a lot of experience working with some of this.

 

[erinszoo]

I have a book, and want to build one one day - I love making pizza and baking bread. You're the first person I've come across who is building one. Looking forward to your reports!

Thanks and welcome aboard! Any hints and ideas are greatly appreciated as it's all trial and error at the moment. I've been reading up on it since last winter from many different sources. Everyone seems to have a little different twist to it but they are all basically the same. I set my goal to have one built before the end of summer this year which is approaching fast so we'll see if I make it. I knew I could get clay from my parents yard if I couldn't find it anywhere else. They have red clay dirt which would make a really pretty colored oven without any painting or dyes but I'd have to drive to get it and I'm trying to make it as cost effective as I can which means not using much gas and finding local materials. Obviously that's not a requirement or anything, it's just a challenge I set for myself. So far I've spent $6.00 in materials for concrete blocks and sand, a miniscule amount of water, and enough gas to get to the lumber yard and the river which is four miles away. The steel plate for the base will be $35 and the most expensive part of it by far.

 

[SuperChix]

http://johndlee.hubpages.com/hub/Ma..._fun__and_makes_a_professional_qualtity_pizza

Now this is cool...they built one of these at the historical site Ft Dobbs in my area of NC

 

[DennisK]

I thought about using various releases, but I am bonding the bricks with a mortar mix, and I didn’t want to compromise their ability to bond to the mortar when I put them to work. I hadn’t thought of lime and ash though …. I’ll give it a try, and thanks for the tip! Come to think of it, I have a vane of talcum rock. I wonder how that will work ..? I don’t have a lot of experience; I just approach my projects employing the trial and error method. That way, I get to experience all of the wrong ways to do things. It seems I have a talent to commit every error possible. It is only when I run out of wrong ways do I stumble onto the right way to do things! The cinder block incinerator was one example.

 

[erinszoo]

I thought about using various releases, but I am bonding the bricks with a mortar mix, and I didn’t want to compromise their ability to bond to the mortar when I put them to work. I hadn’t thought of lime and ash though …. I’ll give it a try, and thanks for the tip! Come to think of it, I have a vane of talcum rock. I wonder how that will work ..? I don’t have a lot of experience; I just approach my projects employing the trial and error method. That way, I get to experience all of the wrong ways to do things. It seems I have a talent to commit every error possible. It is only when I run out of wrong ways do I stumble onto the right way to do things! The cinder block incinerator was one example.

I love the trial and error approach. I tend to follow that line of thinking as well only I also have the habit of being over-prepared for anything I try so then I procrastinate and try to do everything all at once. I don't think the lime/ash would compromise using mortar like a release compound might ... as there is already lime in mortar. I would try using the talcum rock though as you have it. Couldn't hurt and might in the end help.

This week is like dragging along slowly, of course. I can hardly wait til Saturday when I can start laying the clay for the oven. Of course it's fair week this week and we have animals and stuff entered and I judge in open class so we'll be busy busy busy.

 

[DennisK]

Good luck at the fair! I am currently starting a new project developing a spring to augment my well. In the event the pump in the well brakes down, we won’t have to panic with a functioning spring. I have a long list of to-dos, but somewhere in there we want an outside bread oven as we have an interest in homemade bread. I’m not sure of the oven’s design yet.

 

[erinszoo]

I've found in my research on building this oven that there seems to be almost as many ways to build it as there are ovens out there. I love that! That means it's harder to make fatal mistakes in it as many different designs work well.

 

[SuperChix]

Billy and I are gonna do the oven, from the hub page....gonna start it in a week, will take pics and post.. I love to bake bread! google artisan bread in 5 minutes a day, wow good recipe if you like ethnic breads....