Prepare to build the earthen oven
To make the actual earthen oven building day as effective as possible it helps to have all supplies ready. For me this meant getting the base of the earthen oven built as well as having the actual building material available.
Credit: Allen StonerFor the base of the earthen oven I used a 16 foot cattle panel bent to a 4 foot squre filled with local rocks. It was about 2 feet deep when we bent the cattle panel over the top to form our base to work on. On top of the base you will want to put a layer of insulation. The insulation we used was pine shavings mixed with a mud/clay mixture packed around empty wine bottles.
Credit: Allen StonerThis insulation will help contain the heat in the oven and not allow it to radiate down into the base. There needs to be some sort of thermal break or when you're ready to begin cooking the heat will still be radiating out and not back into your food.
The insualtion is a blend of ground, clay and pine shavings. Saw dust can also be used instead of saw dust if you have some of that available. Put the dry mixture on a tarp and mix it together before wetting. When it's well mixed begin to add some water, but don't make it too wet. You just want it to be workable but to hold it's shape.
Credit: Allen StonerAbove the empty wine bottles a thermal heat sink is created with the same material that the oven will be built with. This is to absorb a large amount of the heat directly under the cooking area and will then be used to cook the food. Use more of the insulating material and wine bottles to insulate this heat sink from the open air.
Start to build the earthen oven
Credit: Allen StonerVarious materials can be used for the base of the firebox, preferable some sort of thermal mass type material. Soap stone if you have a piece large enough could be a good option, I used firebrick as that's what I was able to obtain. The down side of the firebrick is that there are lots of seams in the floor of the earthen oven.
On top of the brick floor a sand dome is built to build the actual earthen oven around, and then the sand is removed. Simple play sand is sufficient. Cover the firebrick floor with newspaper and the outside of the sand dome with damp newspaper to aid in the removal of it later.
Credit: Allen StonerMany earthen ovens have an arched door, but I opted for a rectangular door as it's much easier to build. The door should be about 2/3 the height of the sand dome, which is ultimately the inside of the oven.
I also stood a fire brick on it's side around the edge to have some protection for the earthen wall when sliding the peel in to the oven. If I was doing it over I would actually go higher with the fire brick on the inside of the oven.
Start playing in the mud
Credit: Allen StonerWhen building the wall of the earthen oven, be sure to press each course of mud into the previous level of mud. Don't push it into the sand dome, you really want the wall to be independent of the sand dome, it's just there as a guide. The wall is built using the same material as the heat sink under the fire box. The wall should be about 4 inches thick, about the width of a hand.
Try to keep the mud a consistent moisture so that it dries at a consistent rate. The mud should be wet enough to work and hold it's shape. A good way to test this is to roll a snake out of the mud and let it drape off the side of your hand. It should bend and hang down with some slight cracking but not break off, which means it's too dry.
Remove the sand dome
Credit: Allen StonerIt would be best to allow the mud dome to dry before removing the sand dome, but depending on how damp the mud is it may be able to be removed almost immediately. I just didn't have the patience so removed my sand immediately and it work out okay.
Be careful when removeing the sand to not hit the mud wall too much. The paper should give some protection to the wall and let you know that your at the edge.
Build a fire
Credit: Allen StonerWhen the sand is all removed from the earthen oven it's time to start a fire. If the walls are still wet be sure to keep the fire small or you risk drying the mud too fast and cracking it. Unless you keep the fire going for quite a while it will take at least a couple days for the oven to dry out completely. Once it is dry, it's time to use it!
Some things I learned building the earthen oven:
- It takes more mud than you think
- It takes more sand, but you can get it back
- Try to have all these materials available ahead of time, that way you wont have to stop the building process to dig more ground
- Take your time and allocate an entire day
- The bottom of a stream is good place to find clay
- Let the clay dry out and grind it fine to assist with blending
- Make sure the door is wide enough for what you want to cook
- Wear sun screen
Yet to do
Once the initial dome is built the earthen oven is usable, but to make it more effecient a layer of insulation should be added. Without the insulation layer the oven will loose a lot of heat to the open air but adding it allows for much longer cooking from one burn. The insulation layer is the same blend of material as the base layer. This insulation layer is also where you let the artist come out and you can build a fancy earthen oven.
I need to still put my insualtion layer on my oven. It looses heat quickly when the ambient tempurature is low, it wasn't too bad during the summer, but in the winter the cooking time was somewhat short. This will be a spring project.