In many parts of the world, ovens are made out of a mixture of clay, sand and straw. Not only are these materials usually readily on hand and inexpensive, but they also are superior for building ovens that reach temperatures in excess of 700 degrees F and stay heated for long periods of time. Making a Mexican clay oven is simple but not easy. You'll need to be in good shape to mix the heavy clay materials and build the oven.
Things You'll Need
- Knife or chisel
Preparing the Adobe
Evaluate the soil you have to work with. Dig down approximately 6 inches with a shovel and see if you can locate clay. Mexican clay ovens are made of adobe, which is a mixture of clay and straw. You can tell whether or not your soil has high clay content by feeling it to see if it has a greasy texture. You can add a bit of water to it and roll it between your fingers as though you are making a snake. If you can make a snake that is a few inches long without it cracking, you have clay. If you do not have clay on your property, you can purchase some from a construction company.
Lay out a waterproof tarp and put the clay you have dug up onto the tarp. The amount of clay you use will depend on the size oven you are going to make. Count on filling up several 5-gallon buckets for an oven that matches the size of a kitchen oven.
Add sand to the clay on the tarp. Clay oven builder Kiko Denzer recommends a 4-to-1 ratio of sand to clay. Keep in mind that the clay you have dug up most likely already has sand in it. You can get a soil analysis from your local agricultural extension office if you want to know the exact amount. Otherwise, it will be trial and error. If the ratio of clay to sand is too high, the oven will crack easily. Add enough straw to the mixture to help it bind together well---this forms the adobe. You'll need enough straw to make up approximately 10 percent of the volume of your mix.
Add water to the mixture, collect a few friends with bare feet and begin stomping and mixing. Keep going until you have a clumpy, sticky material.
Gather some of the adobe mixture in your hands and shape it into the shape of a brick. Allow it to dry. After it is dry, bash it around a bit to see how easily it breaks. If it is crumbly, you probably have too much sand. Change your adobe mix accordingly, and make another brick. Note: Traditional Mexican ovens are made of adobe brick; however, it is much easier to make the oven out of the mixture itself, without forming individual bricks. You will still have a very sturdy and functional oven, and visually, it is indistinguishable from adobe brick ovens.
Building the Oven
Build a platform for your oven to sit on. This makes it much easier to use. You can build a brick platform or one made out of very sturdy wood. Make sure the dimensions are such that the oven will fit on the platform with room to spare. Place a layer of gravel on the bottom, and top with a layer of bricks that are placed flush against one another. Do not grout the bricks.
Place a mound of wet sand on your platform. Make a dome shape that is even all the way around and just a bit smaller than you envision your stove. Cover the sand with wet newspaper.
Affix the adobe mixture to the form you have made of sand. Make the mixture about 3 inches thick. After you have covered the sand with cob, use a knife or chisel to cut out the door. Make the door large enough to insert a loaf of bread or a small pizza, but not so large that too much heat will escape when it is open. Allow to dry.
Scoop the sand out of the dried clay oven. Don't worry about the newspaper, as it will burn off when you start your first fire.
Build rain protection for your oven. Many people build a simple frame over the oven and top it with a sheet-metal roof. You'll also need a door. You can make one out of a block of wood that is either propped against the opening or cut to fit the door opening.
Tips & Warnings
- You can use the adobe mixture to add designs and turn your oven into a sculpture. Not only will this give you an oven for your back yard but also a work of art.
- Do not waterproof your oven in any way. This will cause moisture to become trapped inside the oven, which will crack the adobe.
- "Build Your Own Earth Oven"; Kiko Denzer; 2007
- Photo Credit pizzas in an oven image by Alison Bowden from Fotolia.com