Accompanying Youtube Video “24-hour Clay Bread Oven”: https://youtu.be/tKRqR4YlYx8
Quite a number of years ago, when we moved from Europe to the United States and I could not find decent artisanal bread for the life of me, I learned to bake bread. This was the time of instant coffee, mainstream beer, and don’t even think of sitting outdoors to enjoy a sip of espresso or a slice of home-baked pie! Thankfully, a lot has changed these past few decades. But like real estate in a gentrifying neighborhood, the popularity of a shot of nitro cold brew, a cold draft of barrel aged mixed-ferment sour or that crunchy loaf of caraway sourdough has propelled these necessities right past me into the realm of luxury. So… what to do? As bread was not something I going to compromise on, I taught myself to bake wholesome bread (and, of course, learned to ferment a decent brew too).
Photo: Our finished beehive oven being primed for baking with teenage enthusiasm.
Guided by an old Mother Earth News article, I tackled the challenge of baking no-knead bread, and quite successfully too. Even the kid will now eat my bread, and that says something! I learned good ingredients make a huge difference, and now buy my locally grown flour in bulk at a local mill. I learned patience is a good thing, and that concentrated heat is key. I added a couple of folding & rising steps to help the gluten in the dough become more elastic and give the bread that springy feel. And I started using a cast-iron Dutch oven to bake the bread in my conventional oven. But what I never was able to emulate was that deliciously crunchy crust…
I had given up on The Crust. Until I had some freshly baked bread at a Living History museum. There was that crust I remembered! And I learned a backyard-altering lesson: it wasn’t the ingredients that made the crust; it wasn’t even the process of making the dough – turns out the crust is determined by the heat and moisture of the oven it is baked in. And a conventional kitchen oven, even when using cast-iron, just doesn’t do the trick.
I am not alone in my search for yummy bread. Humans have done so since the beginning of time. It is easy enough to crack grains and make this into porridge. Or the grains could be milled and ground into flour. Flat breads could be baked by the use of controlled dry heat through the use of a flat bakestone or the surface of the hearthstone itself, swept clean of ash and embers. Not all flatbreads needed to be unleavened (unrisen). A natural sourdough leavening could make a flatbread much lighter and spongier, but as long as the heat comes from one direction – the floor – and the bread will need to be turned to bake through and through, then it will become flat.
Leavened bread was likely discovered by the Egyptians, which had cultured several dozen yeast varieties meant to make different products from bread to beer. When a dough is leavened - either by adding lactic fermentation (sourdough) or alcoholic fermentation (yeast), or a combination of the two – the microorganisms consuming the flour’s sugars will expel carbon dioxide. These bubbles of gas are trapped by the dough, and the elastically expanding air pockets – the magic of gluten - captured and sealed within a crust of sugary starch formed by the exposure to heat is what makes the bread so irresistible. And no tool could do this more efficiently that the oven.
Photo: Medieval bread baking in a brick beehive oven, showing the typical tongue of flame out of the top of the oven door (Getty Museum: Ms. 14 (85.MK.239), fol. 8v) (copyright free)
The first ovens as we would recognize today were dome shaped; an easy shape to build as well as strong in use. One of the earliest beehive ovens found is a Bulgarian oven of over 6,000 years old – and of course the Egyptians used them, as well as medieval Europe and the colonial Americas, among others. The oven I will talk about today is reminiscent of an 18th century Quebec oven and is inspired by an oven I saw at Colonial Williamsburg. The shape of the beehive oven is so effective because the dome-shape gives strength to the structure and its thick walls help trap heat. It is this radiant heat that will bake the bread, not the fire or the coals. I was surprised to see this oven design does not come with a chimney, like fireplaces and pizza ovens, until I learned it took until the high middle ages for full-scale chimneys to become commonplace.
Your beehive oven can be round or oval, tall or squat – the general shape and design of the oven affects its performance, but details are not all that important. Except for the size of the opening. The entrance determines the amount of oxygen that comes in to feed the fire. If it is too small in relation to the height of the dome, the fire will burn frustratingly slow. This is because the opening functions as both the entrance, and the exit chimney – it draws oxygen through the bottom part, and vents smoke through the top. Ideally, the opening should be at least 63 percent of the overall height of the internal space. The oven’s interior determines how effectively it radiates the heat. A circular or oval dome shape evenly radiates heat back to the loaves placed on the oven floor (the sole), but it is not essential. There are many examples of square brick ovens that work perfectly well. The next upgrade to oven structure was the addition of interior vents (and then full chimneys), followed by the firebox being separate from the baking chamber. But now we’re getting ahead of ourselves and into the domain of large-scale commercial structures, which is not what we are going for.
I am interested in building a small-scale single-family wood fired oven which can be constructed using minimal purchased materials. Depending on how crafty you are, this build could potentially be for free! To build a small beehive oven, one would need about 100 lbs sand, 50 lbs clay, water, several handfuls of long fibers, like dried grass or straw, and several handfuls of short fibers, like dried horse manure. Once mixed, this is called daub. To help the oven retain shape, we’ll use one wide board, about two dozen fresh pliable willow or hazel twigs, and wet paper bags, old cotton sheets or burlap.
Photo: Bringing wild-harvested clay back from the swamps with my Icelandic helper.
Photo: The clay we dug up and used for the bread oven. Our natural clay comes out quite pure and only needs surface cleaning for use in daub. We used the play sand from our kid’s old sandpit (with permission).
To make the daub mixture
Step 1: Gather all materials, and measure out the sand and clay. If you have a little less or a little more, that is fine – the important bit is to use 1 part of clay to 2 parts of sand. You can use wild-harvested sand and clay, or you can use store bought play sand and clumping cat litter, either works. Tip: it is not necessary to buy expensive potters clay, clumping cat litter works just as well and comes in a convenient granular shape!
Photo: Bare feet mashing of the clay and sand mixture.
Step 2: Combine the clay and sand. Lay down a sturdy tarp or drop cloth on flat ground and pile half your sand in the middle. Take of your shoes, and add half of the clay. Sprinkle water on the clay/sand mixture to make it damp, and start kneading it with your feet. I think it is more effective - and fun - to use bare feet, but if that does not work for you, rubber boots are fine too. The amount of water needed depends on how wet the sand and clay already is. It is not necessary to slake wild-found clay but do remove any pebbles and other large debris beforehand as certain stones are not fire-proof and can fracture your oven wall. Knead the mixture well and use the sides of the tarp to roll back any clay or sand that is trying to escape maceration. Add more sand, clay and water as needed, until the sand and clay is all used up. The final mixture should be wet enough it just about sticks together when pressed into a ball, but definitely not muddy.
Step 3: Spread out the sand/clay mixture and sprinkle the dry grass, straw and horse manure fibers all over the surface. Then go back in and mix that in as well, adding a wee bit of water if needed.
Building the oven
Take a break and go on the hunt for two pieces of scrap wood: something close to 1x10 rough cut hemlock would do. Do not use pressure treated, painted or glued wood. One piece will be the sacrificial floor or fire board and about 20 inches in length is fine. The other piece will be for the door. It helps to have the floor board and door ready before shaping the oven, so the oven can be shaped to size. My door is a piece of 10 inches tall, 12 inches wide, rounded at the top and with a rudimentary handle on one side. If you want to be fancy, cut a piece of sheet metal or tin to the same shape of the door so the oven heat does not scorch the inside (the two screws of the handle on the other side are plenty to keep the metal guard in place).
Photo: The basket structure on the inside of the clay-bodied oven. (copyright with author)
Step 1: Mark out the outside diameter of your oven. Use the scrap piece of 1x10 by 2 feet or so floorboard, and lay that down on a level piece of ground. Then eyeball a 4-inch thick oval around it to mark out the walls. Remove the floorboard, lay down a row of thin twigs and flatten balls of daub to about an inch and a half thick to make the floor of the oven. The twigs, like rebar in concrete, help the floor stay together when drying. It is possible to build your oven on a platform as long as it is sturdy and heat resistant. For simplicity, my little oven is built on the ground as it is much easier securing the shape-forming twigs. Stacked natural stone foundations, as well as natural wood and 2x4 platforms insulated with a thick bed of sand, are convenient options that will raise the oven opening to an easier working height for those less flexible.
Step 2: Stick long pieces of pliable fresh twigs into the ground to form arches going from one side to the other, to make a sort of rib cage to shape the interior chamber. Start by shaping the door opening, and work your way down the row, making sure the middle arches are higher than the top of the door opening, but no more than about 30-35 percent. Remember, this is the one measurement that is important, as it will determine how well the oven will draft. Then, again starting from the door opening, weave twigs perpendicular to the “rib cage” and form a sturdy basket-weave structure. Fold some of the ends at the door opening over and weave the short ends back in to provide extra rigidity. Stick the ends into the ground to secure them well. The daub is heavy and this basket structure is what is going to hold it until it is self-standing. The basket structure itself will burn away.
Photo: The sacrificial green willow basket form which will support the weight of the daub, which will be burned away at around the same time the daub is fired well enough to stand on its own.
Step 3: Wet your covering material. I found paper bags, old cotton sheets and burlap all work fine. Mold the wet material over the basket structure so no daub can fall through once we start stacking the daub.
Step 4: Starting at the door opening, build up the first layer around the bottom perimeter at about three inches thick. Repeat this to about the point where the wall really starts to lean in. Smoothen the outside and take a break.
Photo: The foundation of the chamber is done; now it’s time to let it dry and solidify, and for lunch.
Step 5: Give the bottom layer some time to dry so it will be less likely to bulge out when the weight of the dome is added. The foundation should be at around three inches thick, which will slowly decrease in width to about inch and a half to two inches at the top of the dome (depending on how much daub is left). Gently smooth the outside with your hands, adding some extra daub as needed.
Photo: Finishing the dome of our little beehive oven.
Step 6: Shaping the door opening is essential, as an opening undermines wall strength and thus is the most likely place for cracks to develop. Use your wood door as a guide and build the roof of the door out until the door opening is at 90 degrees. Give the door arch a mean ridge - make the arch look like a frowning caveman - thicker than the rest of the wall at that height to help make up for the loss of strength due to the opening. Double check there is ample room for the floorboard to slide in and door to sit against, as the oven will shrink about 10 percent when drying.
Photo: Slowly drying the oven from the inside out.
Traditionally, an oven is left to dry naturally over the course of several weeks. This measured drying minimizes cracks, especially in large structures with very thick walls. The little beehive oven can be dried in a similar manner, or it can be forced-dried over the course of hours instead of weeks. But even then, changes in temperatures should be slow, and a small fire for a long time is more effective than a blaze – plus, we don’t want to burn away the basket support structure before the daub is self-standing. Build a small fire using dried grass, dried weeds and dry small sticks on top of the wood board, and feed the fire often. For easy access to the drying fire, build it on top of the fire board and slide this in and out as needed. Keep this small fire going, gradually making it bigger, but not too big, until it is time to go to bed.
Our small beehive oven will be fired with timber fuel. We heat with wood and have an ample supply of hardwood. But hardwood is less ideal for an oven like this as the logs need to season, come too large and are hardwood, which burns long, but does not burn that hot. And with our beehive oven, once it is primed, we want a good penetrating heat. To cold-start our woodstove, we like to use free scrap wood, and I find this wood to be perfect for our little wood oven. Industrial wood scraps like pallets and strapping wood are in a way modern-day coppicing! Generally, the wood is of fast grown softwoods which burn hot and fast. The combustion temperature inside of the oven will be high enough to break down and neutralize harmful residues in the wood we scavenged. It also burns off any resins or flavors that might otherwise linger on the inside of the oven walls. This also means the bread will not taste of the type of fuel burned, whether it is cheap pine, dried manure, peat or fancy hardwood.
Photo: The dried oven used for the first time the next day. Shown are my home-made peel, and repurposed garden hoe scraper (the handle had broken). I cover the shoveled-out coals with a metal barbeque lid so they are deprived of oxygen and will turn into charcoal overnight.
Oven tools that make baking life much easier
- A metal fire iron, the end shaped like an “L”: used to pull the fire, embers and ashes out.
- A metal scraper, similar to a garden hoe (which is what I use): used to remove any ashes the fire iron missed.
- A cloth mob – could just be strips of cotton fastened to the top a stick – to wash the floor of ashes and add crust-creating moisture.
- A peel, a flat wooden scoop with a long handle, to place and remove the dough into the hot oven chamber.
Most of these tools can be repurposed or home-built. Keep in mind metal tools should have an insulating wood handle so the heat does not travel up and burn your hand. It is also nice if the tools have long handles, about 2 to 3 feet seems to do the trick. The belly of the oven gets quite hot and it is nice to have some distance when it is time to rake out the coals!
Running the oven
When the oven has properly dried and is ready to bake bread, light a small pyre of kindling in the back of the oven chamber. The first loaf or two might not be perfect as the oven will cure for several weeks. When the kindling has burned to embers, add larger kindling and small split wood to slowly bring up the temperatures of the chamber. The goal is a clear flame, to produce embers and coal to warm the sole. Don’t be hasty and build a large fire in a cold oven – I know it’s fun to build stuff, but let’s try and keep this oven around for at least a season! As the oven only has one opening, at first, when it is still cold, it will smoke enthusiastically through the front door opening. Keep this in mind and orient it so the prevailing winds are away from any possible open windows - neighbors included. Once it starts to heat up, the smoke will become less and less until it is replaced by a “tongue” of flames. Keep feeding the fire, once every twenty minutes to half an hour, depending on your wood and size of the oven, for at least a few hours.
Photo: An overheated and undercooked loaf – this happens when the coals are not (completely) removed from the oven, or the oven is too hot.
When the outside of the dome feels too hot to touch the oven is ready to start baking bread. Scrape the coals and embers out of the chamber, and clean the oven sole with a mob, a wet cloth brush. This does not only remove ash from the baking floor, but also adds much needed moisture for that perfect crust. With an oven peel, slide your ball of dough into the back of the oven. My oven is slightly oval, and fits two loaves at a time - one in front of the other. Baking times vary depending on the initial heat when the dough went in, as well as on the size of the loaf. Small loaves could be done in 15 minutes where larger loaves could take up to an hour. Experiment, and keep track. It is fine to quickly scoop a loaf out to tap its bottom to check if it is done – it will sound hollow when it is – and if not, to stick it back in for another ten, fifteen minutes.
Photo: Two perfect loaves of no-knead crusty bread.
And there you have it; all you need to know to build your own backyard bread oven and bake some fabulous crusty bread. Keep in mind that the outside of the oven is technically not fired, like pottery, and will be slightly water soluble. In time it will slowly dissolve when it gets wet. To prevent this, we erected a small repurposed metal roof A-frame over the oven and our oven has withstood our summer gales without an issue. It has been such a luxury baking fresh loaves, and the occasional personal pizza, right in our backyard with the family – especially in these times of limited social entertainment. And if you have kids of your own, there won’t be a problem to keep the fire going either, I’m sure!
References
- Mud Oven in 24 Hrs - Start to Finish by Townsend: https://youtu.be/BPQVFQmwZMU
- Building a wood-fired oven for bread and
pizza by Tom Jaine (Prospect Books, 1996)
