Clay outdoor bread oven??

[DennisK]

I am wondering why it is necessary to add straw to the mud mix. Would adding cement to the mud mix cause problems?

 

[jackson41]

The straw creates insulation. You add lots of straw to a clay slurry. In the final layer you add chopped straw for strength.
If you google Kiko Denzer Earth Ovens he has some great info . I don't think you can use cement in the clay mix.

 

[erinszoo]

The straw adds strength to the clay, not insulation. It does dissipate the heat faster with the straw in it but holds the clay together, keeping it from cracking.

 

[jackson41]

Yes it does add strength in the final layer because it is cut short like adding fiber to concrete. The insulating layers use straw also mixed with a thinner clay slurry. This layer should be at least 5 or 6 inches thick. Eventually the straw will burn out leaving a honeycomb layer of insulating clay. You can also use perlite or vermiculite.

 

[erinszoo]

Ok, well, here's our pics from this weekend of building the first layer. We titled our weekend as "mud pies and sand castles".


Buckets of clay soil ... beautiful Oklahoma red


Mixing the sand, soil, and water ... This is the first layer with no straw in it.


The base is four inches thick with clay, sand, and straw.


The base and beginning of walls with just clay and sand mix at 75% sand to clay. This layer is two inches.


Wet newspapers to protect from the wet sand.


The sand dome covered with newspapers and the walls going up.


Here is the finished first layer. It's about two inches thick. We left the door opening open instead of trying to cut it out later.

We spent parts of two days working on this and have used about seven bags of sand so far in the base, first layer, and mound in the middle. We've used three buckets of clay soil. The inside dimensions are 20" x 21" x 18". The height is much harder to attain than we originally thought it would be.

The hardest part so far has been shaping the sand dome and working with the wet sand for inside the oven. It fell all over the place and with wet sandy hands it's hard to remove from the wet clay cob. Also getting the wet newspaper to stick to the sand and stay in place was a pain. The clay cob has been simple to use and work with. It molds together really well. You have to be careful not to let it sag under the weight of itself which comes with shaping the sand dome at the right angles and having a thick enough base.

Now to let it dry for awhile which should work pretty well this week since it's supposed to be in the upper eighties to low nineties.

Fingers crossed.

 

[jackson41]

Your oven looks GREAT have fun! Happy pizza making.

 

[erinszoo]

Thanks Jackson! Now we just have to let it dry ... oh the waiting!

 

[erinszoo]

Well, we pulled out the sand from the inside of the oven today hoping to get it to dry better. Then my hubby decided we needed to make sure the door was the right size and that a fire would draw properly so we built a small fire in it ... of course our wood was wet given it's been misty and sort of raining for three days now ... but it burned perfectly. Hope the little bit of heat we made helps dry out the inside some.

 

[hillbillyfarmer]

An outdoor oven is on my list for next year! I have wanted one for years but never had the time to make one. Hope mine turns out as nice as yours!

 

[erinszoo]

Thanks Hillbilly! I think if you totaled all the time we've spent on it so far, including digging dirt, it's taken about three days. We still have to do another layer on it that will include straw to help hold in the heat and then a thin protective coat to make it waterproof that I get to have fun with decorating. Have fun and post pics when you take the plunge. I'd love to see everyone's.