Blog
It all comes down to mud, well clay really I had suggested it to the National Trust in one of my first scouts of the area when Id found a very pure grey clay along the banks of one of the brooks that runs through the wilderness. However you may find that you have access to clayee soil, its always worth quite literally digging around, as often times a foot or so below the top soil there are significantly different layers of earth.
Once you've sourced your clayits worth grabbing a handfull and squishing it to get a feel for it as a rule the slippier it is the purer the clay. I find that rubbing it between my fingers and listening to it I can hear any sand grinding which is no bad thing.
locating your oven is going to depend on a few things and is all down to your own cicumstances however the things that you should be taking into consideration include;
- Prevailing winds, the oven will occasionally get smoky so the door needs to be downwind and make sure its not going to blow smoke into houses etc.
- Proximity to materials, I try and build as close to source as possible so Im not lugging barrowfulls of clay, earth and sand around.
- Rain shelter, if its going to stay around youll need to consider a roof or cover to prevent rain washing it away over time.
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Space, not only for building ut also when its built how many people will be around? and how much space will be needed for prepping etc.
OK once youve got the location sussed its time to build a base for the oven to sit on, theres a fair bit of weight to hold up so a substantial platform will be the most technichal part of the build. I have seen wooden trestles, dry-stone walls and brick piers all used to support an oven so get creative and start building theres plenty of pics on the web for inspiration. the only important points are stability and that the top of the platform is built as flat and level as you can possibly get it and made from smooth heat resistant bricks fire bricks are perfect (the clue is in the name) however I have used engineering bricks when budgets didnt allow for such extravegance.
Next up comes the oven itself, I start with a sand dome the one in the pic used just over 3 bags of sand with a diameter of about 2 feet. Oven size again is dependent on what your thinking of cooking for a garden / personal oven id go smaller if it got much bigger than 30" Id consider building two. the key is to think what your planning on cooking and work out how much space you will need. Another thing to keep in mid is that the optimum height for the door is 63% of the total height of the oven void. for instance my sand form (Which will be removed when the oven is made) is 27cm high so my door will be 17cm high.
I spent some time getting a very smooth and even form packing the sand down and smoothing it over always keeping the sand damp enough to hold its shape, on hot days a fine spray every once in a while keeps the sand from drying and blowing off. once im happy with that ill wet strips of newspaper and cover the dome, this does two things first off when I remove the sand ill know when to stopp digging and secondly it keeps the form damp while Im making the mix and covering it.
With the form built its time to get mucky, the first layer is a thermal layer and will be storing all the heat from the firing although clay can do this sand is by far the best thing for the job experiment with your mix but anticipate a mix of 3 parts sand to 1 part clay. I use two tests to get the right mix firstly by rubbing and listening to a pinch of clay, at the same time youll get a feel for its texture. secondly by making a tennis ball sized lump of clay between my hands and compacting it then drop ping it from chest height, if the ball squashes too flat I know its too wet and clay heavy, if it breaks apart its dry and sandy so an ever so slightly cracked and misshapen ball is a sign of a perfect mix.
With the mix ready slowly build up a 3-4 inch deep wall up around the sand form as each handful is added pack it down and try to make a continuous blend, as opposed to making wet bricks and blocks. as the layer builds concentrate on compacting the mix down as opposed to into the form. I tend to punch and hammer with one hand whilst holding the outside with my other all the compacting is done parallel to the angle of the sand form not at right angles to it continue mixing piling and packing till you've completely covered the sand form with a good deep layer of clay/sand mix.
As yet there is no door this will be cut once the oven has dried a little. Depending on the weather you can now sit back and be proud of a nice tidy mound of earth youve created. until the clay has dried and hardened a little theres not a lot else to be done.
Once dried on the outside (My test is a gentle press with a finger if it starts to dent the clay then leave a little longer.) you can make a small hole where the door will be and scrape out some sand, gradually as you feel braver and the oven dries you can take out more sand and widen the door a little more. If your in a hurry to bake you can gently warm the void with a small fire, trangia type meths burner or a few tea lights.
The oven can be cooked in at this point however I would recomend a second layer of clay straw and sand to act as an insulation layer and extend the available cooking time, anything from 2-6 inches more is all going to work and it comes down to how much space and time you have. A third layer can be added with higher clay content which can be moulded, carved and prettified so transforming a clay mound into all manner of aesthetic creatures, monsters, shapes and designs.
Coming soon ............ Ive built and earth oven now what ? a few suggestions for cooking with an earth oven.
