It works! I doubt that you can imagine our excitement watching the first flames burn in our oven. Isn't this a pretty sight?
After several days of drying, today was the day we removed the sand dome from the interior of the oven. The clay was completely dry on the outside, but the sand and interior clay are still damp (and COLD).
I was amazed to see how much sand came out of the oven - I don't know why, since we had dug, hauled and shaped it - but when I took this picture, Odel had removed about half of the sand and had filled almost half of the wheelbarrow.
The sand had not dried much at all, except for the moisture that had been drawn out of the sand into the hearth bricks. After Odel got all the sand out, we put a lantern inside and took turns poking our heads into the opening and examining the interior walls. We had a few cracks, but we were delighted to find the inside walls mostly smooth (the point of whacking and compacting the wet clay from the outside).
Once the void was opened up, we built a fire, partly to help dry the oven (which will take several more days) and partly as an experiment. Because fire needs air, and because this oven has no chimney (like a fireplace does) to draw air from the door through the oven, I wondered how well a fire would burn. As our earth oven handbook instructed, we had positioned the door opening away from the prevailing wind - and it burned perfectly.
What else did we learn? That a three hour fire will take more wood than we imagined... well, we really hadn't imagined that part at all, we were so caught up in the building! One of Rosanna's priority tasks is to gather wood.
The most rewarding part of the fire experiment was to feel the oven warm up. The hearth bricks are too damp and cold to heat with our small fire, but the exterior of the dome did warm up. It was a cool day, and we spent an inordinate amount of time grinning like maniacs, resting our hands on top of the oven, comparing the heat on the top to the heat on this side, and that side and - oh, feel it here! Very pleasurable.
After a bite of lunch, we filled our twelve buckets with "slip", a thin clay-and-water mixture, then collected a small trailer load of dry horse manure. The final task for completion of the oven is to apply a protective layer of "cob", the mixture of slip and manure, to act both as insulation and as protection from the monsoon rains that will arrive in July. That's our job for next weekend, when we move our home back to Rosanna's.