Once the loam is sufficiently dried it is time for the oven to be fired. The first fire should be rather small. Each subsequent fire should be incrementally larger than the previous one until the oven is tempered. Once the oven is warmed up evenly by small fires over several hours and the moisture has escaped a strong fire can at last be built in the oven. For this step I kept a strong fire going for 10 hours. This heats and tempers the loam properly and it becomes a continuous solid piece. After this the oven can be fired as necessary to accomodate whatever baking will be done since the loam will no longer tear or bend.