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Question for experienced mud oven builders

susanfnp's picture
susanfnp

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!

susanfnp

 

 

alconnell's picture
alconnell

I removed my sand mold after a day...It was scary, but it didn't collapse.  I figured it would help it dry out that way.  My advice would be start digging and go slowly and it should be fine.  Good luck!

dougal's picture
dougal

Quote:
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.

Unless you can get the thing fully fired BEFORE you leave it (now today), my guess would be that it would be very much more stable with the core in place.  

And if you can make a tent or teepee with your tarp (and secure that against blowing away), I'd think that the worst result that would then be possible would be that your drying process was pretty much in suspended animation until you uncover it again... Or am I missing something important about the process?

Mini Oven's picture
Mini Oven

and let the moisture inside the clay redistribute itself while you're away.  I would cover the clay with old dry rags or towels and throw the tarpin over it and secure it.  Any condense water will trap in the towels and can be carefully removed upon returning.  The structure inside the clay will still compact while you're gone, not a bad thing.  I'm all for the slow drying method.  

Mini O

shimpiphany's picture
shimpiphany

i removed mine after 2 days, when some rather large cracks started showing.  if you don't have cracking, i wouldn't be in a hurry to remove the sand mold.

but it all depends on the moisture content of your building mud.  i made mine dry, so i could get the sand out quickly before the cracking got too bad.  

susanfnp's picture
susanfnp

 Thanks for your input everyone. I did end up removing the sand a couple of days ago, in hope of having the bulk of the drying take place before I have to leave the oven for a good ten days next week -- so hopefully it won't be cracking when I'm not here to patch it. So far so good. It hasn't collapsed yet. Drying is very slow due to cool foggy nights. I'm thinking this may be a good thing.

Susanfnp

http://www.wildyeastblog.com

alconnell's picture
alconnell

Slow drying is probably a good thing...though from what I've read, cracking is fairly inevitable at some point in the process.  The good news is you can patch them.  My oven is kind of work in progress... I don't consider it finished at all.  My next step is an insulating layer, then I want a good door!  It's great fun.

gepp's picture
gepp

Climb hi ,thank you for your info. I use the term plaster to loosely. As per your info i do have an insulation coat of mud on the oven, and it is closed in so as to not let any rain or snow on the oven. Side and back panels are removable for baking. Roof isremovable so i will consider "plastering" it down the road. thank again, gepp

gepp's picture
gepp

grouchpotato, i used a variety of chips that i got from my son who is an avid wood worker.  they consisted  of cherry, pine, mahogany, and oak . i just mixed them all together and applied a 4" layer.