Today we got to work on the actual oven finally. We did the base a few weeks back and have been waiting for the rain to abate. We started out pretty straight with our chisel split bricks, the top 20% though gets a bit dodgy, but we hammered the keys in and it is standing on its own, if not very pretty. Over what you see here will be a 5″ thick layer of mud and straw, to seal everything up and add some mass to soak up heat.
The cooking surface is hard castable. Under that is hard fire brick, under which is soft insulating castable, under which are empty beer and sake bottles. The base is a mortared brick cylinder filled with a ‘lasagna’ layered matrix of large and small rocks, and concrete. We needed somewhere to get rid of all the rocks that had surfaced in our landscaping projects, and this got rid of more than half.
A few strips of bamboo make a quick and dirty arch support for the edges.
Not too bad for a few hour’s work. The bricks are all scavenged, and the dome bricks are wedges cut in half. Arch brick for the door. Left over wedge scraps stuffed in at the apex with mud to fill gaps. The same top coat I used for the big wood kiln will work great for this oven. Inside diameter of oven is 70cm, and inside height is about 46cm. Door height is 63% of the inside height.
The advantage of having the big thick mud exterior layer is that later after a few firings, if the brick dome starts to fall in, the mud dome will remain. Not only that, the interior of the oven will actually get bigger….. : )