Question for experienced mud oven builders
I'm hoping for some advice from anyone who has built a mud oven... BreadNerd? Shimpiphany? Pumpkin Papa? Anyone else?
I'm not sure I understand when I can/should remove the sand form. I finished the mud layer 3 days ago and it feels rock-solid on the outside, although it still looks wet (i.e. the mud is dark in color) in most places. The weather is fairly warm and dry during the day but cool and damp at night, and the oven is in the shade most of the day. The few places where it looks like it has dried out during the day look dark again in the morning. I tried covering it with a tarp last night but that backfired as there was lots of condensation inside it in the morning. Denzer says the sand can be removed when you can just barely dent the mud inside with your finger. Well, I'm not sure how you'd check that without removing some of the sand, so I scraped away a little just inside at the top of the archway, and it definitely feels damp and has a little give to firm finger pressure, though I'm not sure I'd say I "dented" it. The mud doesn't have any cracks in it yet.
I need to physically leave my oven tomorrow, although I'm hoping to be able to get back here a day later, for one day, then I'll need to leave it again for another couple of days. If I haven't seen any cracks, should I just leave the sand in and see what it looks like when I return? Also, what do you think about leaving the oven covered with a tarp while I'm gone? It will impede the drying, but if it rains (which is highly unlikely but not impossible) will I be sunk?
Thanks for any input!