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The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

The oven mud could have been more clay-ey, but most of the oven has held up well. Not so the part that wasn’t as compacted (it being over the 0pening)  and that gets the most abuse, namely where the door, when fully closed (closing off the chimney) hits it.  It started crumbling.

DH bought some stainless steel bands at the local HD and bent them to the shape of the door. In the picture you can see that, with the door in place, substantial gaps had developed. With the bands in place, DH could fill them up.

Then we made pizza.

Still not trusting the heat retention capacity of the oven, and pushing up against dinner time, we opted not to stoke the fire for another hour and not to clear the burning coals out, but to instead move them to the back of the oven and to keep a little fire going there.

The first pizza puffed up the moment it hit the hearth (measured at 900 F), its cheese bubbled merrily, and it was done within four minutes.  The next one did well too, except that some of the newly added mud came down, adding some minerals to the pizza toppings.   Yum!

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Unfortunately, because we had opted to keep the fire going, we couldn’t close the door and keep the heat in. Whenever we did, oxygen starvation made the fire die down and the oven filled with smoke. Mud is okay to eat, smoke not so much. The next pizza needed a little more time but came out well – only a larger chunk of oven mud came down.

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Still perfectly delicious. By the time the last one went in, a good half hour after starting, the oven had cooled too much (hearth at 350 F) and that pizza was hardly edible.

Lessons learned:

  • Stoke a hot fire for two hours.
  • Clear out all the coals {read update}
  • Clearing space that way, load the oven with larger or more pizzas.
  • Keep the door closed as much as possible {read update}
  • Work faster.

We checked on the opening and the gaps are still plugged, so the mud that came down must have stuck out and not had enough support to stay in place while wet and being heated so drastically.

{Update}: Kiko Denzer commented on this post with some great advice about the crumbling, the heat retention, and the best way to make pizza. I’ll just reproduce it here:

Hey, congratulations on the beautiful oven and pizza. You might try sweeping the oven dome to remove loose stuff before your next firing. Once you get rid of the worst of it, it should stop dropping (unless your mix was too low in clay). It also sounds like there may still be some moisture in the subfloor (quite possible, even likely if it didn’t get time to dry before you laid the hearth floor). If so, performance should improve dramatically when the last of the water finally gets driven out. When that happens, the standard method for pizza is not to clean out all the coals, but to maintain a small, bright fire in back, and to work with the door open. At typical pizza temps, you can expect them to cook in 1-2 minutes (assuming thin crust, light topping — official Italian pizza standards!) For all your other cooking adventures, see Richard Miscovich’s new book, From The Wood-Fired Oven. And good luck! Thanks for the good story…

I recommend that you watch his video on burning a clean, hot fire in the oven, here on his website. It’s good advice, not just for earth ovens but for wood stoves as well. I’m happy to say we do all he recommends, and better now than before now that I’ve got the hang of my splitting ax.

Thank you, Kiko!

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“Mama, can we bake cookies?”

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Because I suspected that the oven is still too wet to retain enough heat, we put the cookie tray right on the coals (which is cheating, really).

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The thermometer went up to 400 and then freaked out.

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Cookies came out a little burned but nice and smoky!

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Steam rising off the oven.

As an experiment, after that first batch I raked out the coals and we put in another tray of cookies. Like I thought, the temperature quickly plummeted to 250 F. That means we don’t have enough heat retention yet.  I got the coals out of the bucket and put them back in, then flipped the cookies over, like pancakes. Yum!

The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

Advice for the novice bricklayer: when building an arch, when done, remove supports and then let cement dry. You guessed it, when removing the supports under my hastily built arch, the structure sagged minutely, cracking the dried cement. The arch stayed up because all the bricks were wedged, but it wasn’t very stable and, most importantly, the door no longer fit. Positive side: it wasn’t hard to dismantle the loose parts.  We also took advantage of the opportunity to fit the door well into the thermal layer, like a plug. Then we built the new arch, with four hands. And removed the supports.

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While that was drying (and while another peck of apples was drying in the dehydrator), we mixed wood shavings with clay slip and started on the second, insulating layer (about 3″) on top of the outer rim of the hearth which was made with the same material. Denzer in his book likens this to the candy shell around the m&m, or a blanket: a nice, tight envelope to hold the heat in.

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The idea is for this layer to have lots of air pockets, so you don’t compress it as much as you do the inner, heat-retaining dome. Still, I was a little nervous because the trick is to press down, away from the inner dome, which might collapse under such pressure. It’s especially tricky once you hit the top to the dome.

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This took us a good couple of hours, and we needed more of this stuff than we had anticipated. In the end we were scraping the bottom of the barrel for that good clay soil. But here it is, a fully functional earth oven – it just needs drying out.

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At the top of the arch there is a small opening that will become a chimney (to be added when we put the last, decorative layer on).

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When initially firing the wood, the door sits to the front of the arch, keeping the chimney open, like so:

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Once the oven is hot enough and you remove the coals and ashes and put in the food, you push in the door so it plugs the gap, sealing the heat inside.

You know you’ve hit a critical point in a multi-stage project like this one when you get to clean up. I also got my splitting ax out an finallyd gave it its first test run, chopping logs into smaller sticks. “Is this the life or what?!” I proclaimed several times as I swung that ax.  DH agreed.

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We built a nice big fire and I minded it while peeling and chopping apples for more sauce.  The wasps soon found out, and when I was done there were about 10 of them enjoying the juices. It was a little annoying but I found that walking round the table and generally staying in motion really helped. This one I file under the topic of making peace with the true masters of the Earth, the insects.

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A friend asked me why we built such an oven. There are many reasons: our electric oven doesn’t go up to pizza temperatures (800F), you get to cook outside, and, well, there is fire. We all three of us love fire. The first fire in the wood stove is always a ritual, splitting wood and getting it into the porch is a family event, and we can watch it, feel it for hours.  My friend doesn’t have a fire place or wood stove, so he doesn’t understand, but to have added yet another locus for fire to happen (in a controlled way!) feels like a tremendous enrichment.

The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
    1. Patching up, and first pizza!

Today we dug out the sand form.

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We peeled off the newspaper and checked out the surface on the inside. It’s pretty smooth.

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After that, we lit a fire, just a small one, called a “drying fire”.

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 Amie had the right idea. Marshmallows!

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There is something so comforting about a fire on a cloudy, chilly Fall day.

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After that we started building the arch. We had begun one with the oven mud (you can see it in the first image), but that wasn’t strong enough to glue the bricks together enough for structural support, so this time we opted for cement. Unfortunately, DH had to leave unexpectedly and since we had mixed a good amount of cement already, I wanted to continue. Half an hour later it started to drizzle! I finished the arched hurriedly. I think it won’t be too bad, but an extra pair of hands and eyes would have helped. We’ll see what happens when we remove the door and the supports! The thing’s covered with a tarp now, so we will have to wait till tomorrow to try. If it doesn’t rain, we’ll add the insulating and sculptural shell.

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The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

Today we worked on the oven again. Rain threatened but never materialized. It made for a warm, overcast day, just perfect for some more or less hard outdoor work. First we formed the sand form. This was a lot of fun.

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It was like a day at the beach. But with chickens.

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They were all outside and curious. Then an owl sang out, three times, in the middle of the afternoon. I’m used to hearing them around midnight. Then Amie and her friend herded them into the run, where they would be safer.

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It’s important  to get the right height (16″) and a convex shape, because apparently that makes for more even thermal movement. We wetted the sand a bit, and overall it was easy to achieve a nice shape, it just took a while, and a LOT of sand (five 50 lbs bags).

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In order to protect the sand form, you can put strips of wet newspaper around it.

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Then it was time to pack the oven mud around the sand form, making the inner shell, the thermal mass that will absorb the heat during firing and release it during cooking. Because we’d need a lot and because we used the more clayish soil that came from deep in the hole we dug, which was a lot heavier than the oven mud used for the hearth, I opted for a quicker way of mixing it:

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I made many, many batches. The inner shell is supposed to be 3″ thick, but because of bulging due to the oven mud being too wet in places, a lot of mud went into that shell.

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The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

So far, none of the Earth Oven preparations, the foundation and the base, have had nothing to do with heat. Which is, of course, what the oven is all about. Heat becomes the issue and challenge with the hearth, upon which the wood will be burned and the food, not, we hope. Since the hearth is a very important part of the oven, this is the stage where we started becoming a bit more careful and since it finally involves clay, we also started having more fun!

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Wood shavings and clay slip (a very watery clay) make a great insulating material. Over time, the sawdust will burn out, creating small pockets of air, which is the best insulator (as long as it can’t move or escape).

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This was a lot of fun. So tactile. The whole family got into it.

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We buried empty wine bottles (again, pockets of air) in this insulating stuff.

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Now we’re really talking thermal. This is the first barrier between the cold stone fill beneath and the heat that will develop up top. We buried the bottles up to their shoulders, then leveled with sand.

The oven has three shells:

  1. the inner one, of “oven mud,” which will directly absorb all the heat,
  2. the middle shell, of insulating material,
  3. the outer, decorative shell of clay, straw, and some rain proofing material.

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As we had started with the bottom of the middle, insulating shell, we built that up, creating a ring up to the right height (3″ give or take):

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We were ready to start on the inner shell of oven mud, which is just clay, sand, and water. This is the stuff we tested earlier, with our bricks. This shell will absorb the heat during the burn and release it during the bake. It’s easy to mix an oven mud that is too wet. While mixing it,  make a ball out of it often and you’ll see that even though it’s quite crumbly, it makes a strong brick.

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The test is to drop it from shoulder height. It shouldn’t shatter (needs more mixing), and it shouldn’t go splat (too wet). This batch needed a little more mixing.

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This stick insect was intrigued

This shell envelops the oven bricks. After filling up the space inside the circle, about 3″ high, we placed the 22 oven bricks. At $60, they were the most expensive part of the project, as most of the other stuff (except for some bags of sand, gravel and cement) came straight the property.

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It’s important to have as few gaps or cracks between the bricks, as those will capture ashes and food residue. Also, make them as level as possible, so the food or your sliding tools like the rake to pull out the ashes or the pizza peel, don’t catch on it.

Then we made the door out of 2 by 4′s . The shape it that of our pizza peel. Here it is placed where the door opening will be. You can also see the beginning of the sand form. Stay tuned!

The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

Wow, third blog post today! Be sure to scroll down!

Today we finished Phase 2 of the Earth Oven works, the Base. (Yes, we had a busy day today.) For Phase 1, the Foundation, read here.

We thought about building a circular brick wall with an opening in front and leaving it empty inside, so we could store wood there, but the issue was then what to top it with for the oven to rest on. The only thing we could think of that would hold the weight were the 4×4 pressure-treated landscape timbers that we could place side by side and cut to size and shape. But we didn’t like introducing the chemicals they treat those with, or the wood itself, as wood absorbs a lot of moisture. Again, you want to avoid moisture  because it expands when it freezes, thus moving the base and cracking the oven. So we decided to build the brick wall – having heaps of old bricks which used to make up our old patio – and filling that with more urbanite.

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I had never put down brick before, but as DH was travelling it was up to me. (Not that he had laid brick before either.) I put down six rows in two days. On the first day I discovered it’s a lot easier and a lot more fun to work the mortar with your hands, not that clumsy trowel. At the end of that day I also discovered there’s a reason why masons don’t use their hands. By the time I became aware that the sharp sand particles had scratched up and even invaded my finger tips, it was too late. Ouch. On the second day I donned nitrile gloves, which afforded good enough protection and still allowed my more tactile approach.

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We filled up those six rows with more “urbanite” from a big pile of rocks and stones we dumped at the edge of the property five years ago, when we dug out the veg garden. Who knew that would come in handy some day! Then we added another three rows of brick yesterday, and another two today to reach a recommended, comfortable height of 36″ at which to have the hearth – so as not to have to bend over when filling with firewood or pizzas.

We thoroughly tamped down the fill so that it won’t move. Here’s me putting all my weight to/on it, the queen of the castle ordering: There is to be no moving! 

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Here’s DH and the finished base: 11 rows of bricks, tons of urbanite. Tomorrow we add Phase 3, the Hearth.

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The Earth Oven series:

  1. foundation
  2. base
  3. hearth
  4. thermal mass
  5. first drying fire and door arch
  6. insulating layer and chimney
  7. Patching up, and first pizza!

For our wedding anniversary DH took the day off so we could start building our earth oven. Yes, that was our anniversary present to one another. People tell us we’re the most romantic couple they know! We’re following Kiko Denzer’s Build Your Own Earth oven, which I highly recommend and are making the 22.5″ (internal) diameter oven. Phase 1 was to dig down to below the frost line.  We finished this phase on my birthday. Yes, that was my birthday present! Well, one of them (you may remember I also got an axe).

We began by excavating a pit, 50″ in diameter, three feet deep to get below the frost line (except for a “shelf,” where the installers of our patio had already dug down and laid foundation). There were some huge boulders in there.

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We sifted the soil  from the rocks as we went along, using our compost sieve, a very handy thing built in 2010 and still standing.

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Then, in the last foot and a half or so, we found a lot of yellow, fine soil that we got very excited about.

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We thought it was clay. You need clay for the earth oven itself, and we really wanted to harvest it from our own property. However, when we did the clay test, we were disappointed. It precipitated (separated from the water and sank down) way too fast.

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Another test is the brick test. We made seven bricks in the end, each with different ratios of the stuff we thought was clay and the soil above that.

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While we waited for the bricks to dry in the sun, we started re-filling the pit with a mix of “urbanite,” a term for anything and everything you can find on your property, with however as little fine soil as possible. You want minimal compaction as well as really good drainage so that there’s as little possible water in the foundation that can expand when it freezes, thereby moving  the base and causing cracks in the oven.  Hence the sifting, which was a pain we would otherwise have dispensed with. So we threw in the boulders we had just dug up, all the rocks and pebbles, as well as broken pavers and bricks. We filled up the small spaces  in between these and stabilized the whole mess with coarse sand and crushed pea stone that we got in bags from Home Depot.

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We topped the whole thing with gravel (also from the ‘Depot).

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On top of that we placed cement pavers left over from the patio project, taking care that they were level. These made the foundation for our base.

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Of the seven bricks one seemed strong enough to be used as the “earth” (clay) for our oven. It remains to be seen if it will be enough. About that, in “Phase 3.” But first, Phase 2: the Base.

My parents are here and two of the projects that were mainly my dad’s are the chicken coops. The new small coop needed a roof:

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The big coop needed an extra run:

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The new part is that still blonde wood box and the front part. Their run space has more than doubled. I hope this will alleviate the broodiness/quarrelsomeness/pecking that has cropped up lately, especially by the time we introduce the two new chicks in a few weeks.

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It’s a palace.

The two new chicks – Oreo and Nocty – are hale and healthy and growing like the weeds, a little over two months old now. They were cooped up in a large crate on the porch at night and in the “table coop” for most of the day. I liked neither, the latter not predator safe, the first taking up too much space on my porch and the smell too close to my kitchen. So over the last couple of days I built them a small coop, which we’ll also be able to use as a tractor and as a place to isolate a sick chicken. DH was traveling and then down with a bad cold, so I did this all by myself – though I had some help from friends for the initial frame. Most of the materials, except for the screen and the latches, were scrounged from what I had lying around. The paint was a $2 oopsy from Home Depot.

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I debated about whether I would screen the bottom too, and decided to do so, to make it entirely predator and thus worry proof. A thick carpet of straw and a tray of sand and dust makes scratching and dust bathing possible again.

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It comes apart in two pieces and is very movable that way, but I’m planning to somehow attach a frame with handlebars and the nifty wheels on Amie’s old stroller to make it into a real “tractor”.  One last thing it needs now  is a permanent roof over the coop part and part of the run. For now a tarp does the job, to keep Andrea out ;)