I learnt a couple of lessons along the way. The initial firing was at times very smokey. As far as I could tell there were a few clear reasons for this.
- The great amount of moisture being driven off the adobe surround by the fire. Most of this I guess goes upwards and through the roof - but I'm sure a lot goes into the oven chamber and affects the burning process
- The temperature of the oven surround seems to have a big impact. Once this gets up to the point the black smoke burns off you can sustain a big fire.
- The difficulty of creating a sustaining flow of air in, and smoke out. I got around this by bending a piece of aluminium sheet into the shape of a tube. This let me provide a clear path for air straight into the burning wood. You can see this in the picture below. (Notice that we put a layer of straw/pumice cob on top of the oven to help insulate it. As far as I can see the thicker this is - the better.)
All in all it was a resounding success. I need to work on a door now. Something to close the entrance sufficiently well I can bake bread.