Remains of earth ovens with rock heating elements of various sizes and configurations are common at hunter-gatherer sites around the world. They span  the last 30,000 years in the  Old World and some 10,000 years in  the  New World.^[1] Reliable identification and interpretation of earth ovens requires documentation of heating elements, pit structure, rock linings, and various remnants thereof. Wood-fired earthen ovens are easily documented all the way back the ancient Romans. Likewise, they are easily documented in archaeological evidence and first-hand accounts from the 18th Century.^[2]

The temperature and duration of a fire are dependent on type, quality, and amount of fuel; the availability of oxygen; and how the fire is contained (or not). As fire burns, it heats the air, which expands, rises, and becomes “lost” to the atmosphere (diffused) unless the heat is confined or transferred to something in the immediate vicinity. Escaping hot air causes the fire to draw in more cool air, which repeats the cycle in the heating process known as convection. Fires also radiate heat as thermal radiation. Infrared waves move through the air and only release heat when they strike a surface that can absorb them. This is what warms your hands when you hold them near a fire. Fires built on flat surfaces or in shallow basins lose most of their heat quickly through radiation and  convection.^[1]

Whether to build the oven suggest or a different design, it is encouraged to prioritize location. To choose a site, imagine cooking in the oven and serving the family and guests. An oven that isn’t used is just an outdoor ornament! Also closest to the kitchen is best to minimize long round trips if items were forgotten, and if the oven and kitchen are close to each other. The more changes are to utilize the earthen oven regularly. It is recommended an oven 36 inches in diameter built on a sturdy wooden table, with a thick layer of insulating material between the oven floor and the wooden tabletop. Protect it from the rain with a tarp or a simple roof, and you’ll have a beautiful oven that will last a lifetime.^[3]

The list of materials needed: sand, dry clay, straw or dry grass (even hay works), bricks (fire bricks are preferred), canvas tarp (to mix your cob together with), and of course water. The project you’re about to mimic has a dome of 22 inches, 6 inches thick walls and an entrance of 12 inches across. As you will see in the video tutorial, the work resembles playing with sand on the beach; at least in the beginning.^[2]

The extremely high interior temperatures and near-magical cooking properties of a cob oven are due to the fact that cob ovens cook food using all three forms of heat transfer:

1. radiation from the walls and roof;
2. conduction from the surface of the fire bricks to the food;
3. convection from the hot, steamy swirling interior air.

Conventional/electric ovens, at best, only use radiation and convection. Unlike wood-fired ovens, electric coils impart no additional flavors or nuance to the foods cooked inside of them.

Step 1: Pre-Soak the Oven Door – Don’t forget this step or you’re not going to be able to cook! Always soak your wooden oven door for at least 6 hours before you plan to cook. Put it in your sink or bathtub and place a rock or weight on top to make sure it’s fully submerged. The wood needs to be thoroughly saturated before using the door to prevent it from burning. The other function of the soaked oven door is to add steam to the interior of the oven when cooking your baked goods, helping get that gorgeous, crunchy crust on your breads and pizzas. You can also throw in a couple of cubes of ice once the dough/raw pizza is in to get even more steam (the ice cube trick works in a conventional oven as well).

Step 2: Start the Fire – You’re going to create a little flammable teepee towards the front center of your oven. Use small pieces of paper, dried leaves or other similarly textured materials. Over this pile, place your smaller twigs. On top of the twigs, add a few 1-2″ thick sticks. Ideally, all the wood pieces form a rough teepee shape to allow optimal air flow into the pile and prevent the pieces of wood from rolling away as the paper burns and collapses. Next, light the paper with a match. You might have to give the pile a few puffs of air. Add more twigs as the starter fire gets going.

Step 3: Grow The Fire – Your goal is to maintain a steady, medium sized fire in the center of the oven for 2-3 hours before cooking. The longer you burn your fire, the more heat will be absorbed by your oven, and the longer your oven will stay heated while cooking. The biggest pieces of wood we use are about 3-4″ in diameter. We keep the fire directly in the center of the oven as we’re warming the oven, not the front like our starter fire (push the fire to the center with your garden hoe after 15 minutes once or once it’s established). Slowly, you’ll build up a nice base of coals so all you’ll need to do is add more 3-4″ wood logs every 20 minutes or so. Again, you do NOT want a huge roaring fire with flames shooting out of the mouth of the oven.

Step 4: Is It Hot Enough To Start Cooking? – Over time and with repeated uses, you’ll develop your own intuition about how hot the oven is, when it’s time to start cooking, and whether it’s time to put the next food item in.^[4]

1. ^ ^{a b} "(PDF) Hunter-Gatherer Earth Ovens in the Archaeological Record: Fundamental Concepts". ResearchGate. Retrieved 2018-10-08. {{cite web}}: Cite has empty unknown parameter: |dead-url= (help)
2. ^ ^{a b} "How to Build a Wood-fired Earthen Oven (A Low-Cost Project) - Walden Labs". Walden Labs. 2015-11-04. Retrieved 2018-10-08.
3. ^ "Building an Outdoor Oven - DIY - MOTHER EARTH NEWS". Mother Earth News. Retrieved 2018-10-08.
4. ^ "How To Cook In A Wood-Fired Oven (Cob Oven) - Tyrant Farms". Tyrant Farms. 2016-10-25. Retrieved 2018-10-08.