Drying oven, more experiments

I haven’t baked since my last episode where I burned the floor boards under the oven. I’ve been thinking about how to warm the oven and dry it without overheating the floor. What I tried, with fair success was putting 8 broken red brick on the floor, end to end, with a thumb width between them to let air flow under the fire I would build on top of the brick.

I started at 9 AM with a small pine fire, then slowly added charcoal briquettes. I kept things going with bits of wood and more charcoal, but never very hot. After noon the outside was warm (uncovered and in the full sun, ~50F by then). I measured the surface temperature with a hand-held IR thermometer. The highest reading was 117F on the top, 85 on the sunny side, 75 on the north side.

About noon, I pushed the coals to the sides of the oven (off the brick) and added kindling and charcoal. My goal was to put more heat at the edges of the oven. Around 2PM I put in 6-8 pieces of mixed wood, mostly firewood scraps. By 4PM it was coals and I pulled out the red brick and the coals and allowed 30 minutes soaking Several of the red brick were hot thru my insulated fire gloves. I should have sequestered the coals with the hot red brick and left all that in the sides of the oven. An oval oven would facilitate this chipmunk-cheek strategy. Need to look back at how I thought the oven deck was too small and augment that by 6″ left and right.

I had repaired the inner face of my baking door by rebuilding the cob and had propped it in the doorway of the oven to fire the clay for awhile. I took care to put wet cloths in the door to get a tight seal and covered the chimney with a rag and a board and brick as well as shutting the damper. At 4:30, the thermometer read 450F, which seemed too hot for the bread in metal pans. I put a couple of the red brick back into the oven. They were warm to bare hands. And put the bread on the brick. It would have been better to be prepared with something thermally lighter to serve as hot pads. I think I have an old BBQ grill that could provide a 1/2″ spacer.

In 45 minutes the bread was beautiful and the temp read 350F (disappointing, given my first experience with how long the oven stayed hot. Did the earlier bonfire approach get a lot more heat into the mass?). I pushed the bricks to the sides of the oven and slid in 2 quiches. Twenty minutes later the quiches still were very runny, so they moved to the conventional oven.

With the quiche out, I put in a covered pyrex dish with a lamb shank that said it should be braised at 300F. The lamb came out at 8:30 and seems moist and completely cooked, but the temp has fallen to 200F. I think there is radiant heat in the oven that belies the air temp measured by the thermometer. Things cook better than the thermometer would make you think.

I still don’t want to make a massive foundation, next step is to design a better insulated floor that can take high heat and build another oven.

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2 Responses to “Drying oven, more experiments”

  1. One small step for man » Blog Archive » First baked dinner Says:

    […] 3:15 still cold and damp outside, clear smoke, all wood burning well or already coals, added 2×6 and 2×4 elm pieces (these were a mistake, as we will see). Wooden oven door is charing where cob is not protecting it from the fire’s heat. (Cob will need repair by February) […]

  2. Dismantling my mud oven « One small step for man Says:

    […] Back when I built my oven, I’d been using Kiko Denzer’s book (now in new edition). He suggested an oven could be built on saw horses with a wooden plank subfloor, but that it would burn through eventually. I’ve previously reported my notes of that problem happening (here) and (here). […]

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