While I waited for my cement to harden, I bought normal clay bricks from Langkloof brick yard. I worked on roughly 1,000 brickes for the oven, including the base. I also started collecting clay from a farm in the area, building sand and cutting grass. The clay had to be worked with the feet to achieve the perfect consistency! I then mixed the sand and grass to the clay and stomped this mixture thoroughly.
In my first oven, I mixed one part clay with one part sand and half a part grass. Considering that the oven worked very well and I had experienced no cracking, I was not going to deviate from that recipe.
It was hard work to mix everything together and be certain it was mixed well - this is a crucial step! I added water until the clay had the consistency of building sement.
When I was certain the cement was hard (after about two weeks of keeping the cement base wet!) I lay the first layer of clay bricks on top af the clay mix or mortar. I decided on a small narrow chimney to maximize the size of the inside of the oven. I designed the oven so that the chimney would be choked when the door is closed, thus creating a sealed oven for baking. The fire would be burnt out and the oven cleaned before bread is put into the oven. When making pizza or baked vegetables, for example, the door would be kept open with a fire right in the back of the oven.
After the first layer, a base layer of clay brick was added on top of the cement base. Now, it was just a question of building the wall to the desired height. Each brick was dipped in water before building and was kept wet during the whole process. It took a full day to build the walls up to 650mm (including the base layer).
Over 3 days I slowly raised the temperature to 450°C. I found that a lot of heat was escaping through the roof. I allowed the oven to cool completely and built a third layer of bricks over the existing roof. I first had to wet the roof to get the cob mixture to bind with the existing dry cob. I left the roof to dry and slowly fired her up again. This time I raised the temperature to 760°C. It surely was very exciting and the sense of achievement was well worth the effort. The oven kept the temperature very well, 12 hours later the temperature was 400°C, 16 hours later I baked a sample batch of bread at 250°C for 30 minutes. Well, the oven is fired and definitely hard enough by now - time to bake some bread or invite some friends for a pizza. While the oven was dying, I spent time on deciding on the breads I want to produce, sizes and weight. I have made a French country bread which was rustic in appearance and texture, and with a rich strong flavour.
