The pizza oven is finally finished! Not quite dry yet, but that will happen. The last bit of work involves uncovering the oven, letting it dry out, and paddling it to compress the clay. This helps keep the cracks smaller and the clay to be more dense (better heat retention, less insulating).
Before firing it the first time, we will use a scraper and brush on the floor to get the little bumps and grit knocked off, then it will be good to go…
Will keep you posted on how the oven holds up over the next few years.
Well, I wasn’t expecting this to happen, but the pizza kiln has turned into a fetish kiln, at least for the time being. Actually, budget fetish, since I couldn’t afford a nice black latex wrap…
Here’s what happened: We finally got the end of rainy season, and have been out working in the yard, finishing up various projects. I saw rain in the forecast for the next few days and decided to get the kiln finished and covered. Oh, and also the big pile of cob I have under the double tarp is starting to get stiffer from the sun, in spite of the good covering.
After digging into the pile of cob I found out that only the very top is getting stiffer, but I had started the job and decided to get something accomplished. After laying in the first 30cm or so, everything started to sag and the more I pushed it up, the more it would sag back down. Pretty soft. Well, I remembered I have a left over roll of plastic used to wrap palettes to keep the stacks from falling apart when the forklift manhandles them. So, I wrapped up the kiln starting with the base and working my way up over the cob. It really worked like a charm, and I was even able to push the material up and have it stay there, because the wrap is under quite a bit of tension. It is not very strong though, so what you see in the pictures is about 7 layers of wrap over the cob. Quite strong in layers.
I expect that the brick will absorb some water from the cob, and the summer heat will help some of that water out of the mix, making it stiff enough to start paddling in the next few days. If we paddle everything and get it nice and compressed over the course of the next few weeks, the worst of the cracking can be avoided. All that is left after that is to decide whether to leave it a simple dome, or add some sort of decorative motif. Oh, and bake pizza and bread.
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….. : )