Saturday, November 17, 2012

Building an earth oven

What is this?  An earth oven.  What does that mean?  It's an oven made of clay which can attain heats of over 800 degrees.  It can also hold a hot temperature for a long time.  You can make pizza, bread, and anything else you would cook in a regular oven.  However with the really hot temp of 800 you can make traditional italian pizzas in 3-4 minutes.  With the clay and it's heat retention you can make superior breads.   These guys are making 4 minute pizzas and selling them for 7 bucks. 

There are all sorts of instructables on how to make one of these.  Here's how I did mine..

First you lay a foundation.  This one is a freestanding one out of stone pulled out of our fields.  You could use cinder blocks or garden pavers.

Then you find some clay.  You can see the clay layer in this creek bed is by the water.  It's redish brown.

Here I found a nice grey clay layer. 

After I dug the clay, I spread it on a tarp to dry in the sun.  Then I pulverized it with a sledge.  This made a nice powder that would consistently mix with the water.  I tried a couple other ways too, but this was the easiest.

So I would bang on the clay a bit, then put it on this old screen on top of the wheel barrel.  All the smaller poweder went through.
Ahh a very nice clay powder.

The first layer in the oven is insulation.  So to make that you mix a loose slip of clay.

A close up

Then you mix that with straw, or sawdust, or some light airy material
So this layer keeps the heat from going away from your oven.  You want your oven to hold the heat, not the platform.

So you spread that all out.

Add a layer of bottles to create even more dead air space for insulation.

Cover them all up.

Get some sand.  I got a truckload for 30 bucks.  You could dig it.  You're looking for sharp edged sand so beach sand is not as good.  The sharp edges are supposed to hold it together better.  This is mason sand in my truck.

So you mix some sand and clay to make a thermal layer.  I ended up using a cement mixer.  We already had one.

You can also mix things on a tarp.  (no sand added yet and this one was too wet)

You put the clay sand down on top of your thermal layer.

Then you put some fire brick in there.  Get it all tight and level.

We tamped these down a little more after this pic.  They need to be all smooth so you can scoop up pizzas off them.
Then you make a big sand castle over your bricks.  Mine was 16 inches tall.  When it was done it looked like a nice oval dome.

Then you cover it with wet newspaper.

Mixing some 2 parts sand to 1 part clay.  Get a 4 inch layer around your sand form.
Mine was a little wet so I gave it a girdle until it set.

When it's dry enough you cut out a door and pull out the sand.
The door.

The inside.

All done.  Time for it to dry some more.  Then you slowly fire it up to dry out the clay.
Fire it up!

Make your pizza.

Bake it up.  I'm still working on a nice front door for the baking.  Until then, I'm just using a board.

The best crust, and perfect baked cheese.  Only takes 3-4 minutes.

Best pizza ever!

So If you would like to build one of these.  I suggest the book Build your own earth oven.  It rocks.  Another thing I may do to my oven is to add a insulation layer over the top of the oven.  It would be another straw one like at the base.  I would then put a layer of clay on the outside to make it look nice.

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