The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

clay oven project

willwork4SD's picture
willwork4SD

clay oven project

I am in need of some advice/input regarding my finish layer. (I just joined this site but I have been lurking for a while. It has been a great resource for bread and oven building.)

 So here is my question; would it be ok to put burlap over the insulating layer, then apply the final finish coating?(it will be sand/clay/wheat paste/fine fibers) I ask because the insulating coat is perlite, clay slip and natural rope fiber, which I have lightly textured to accept the next layer. It looks dry, and has developed some hairline cracks on the dome. I was hoping that the burlap would provide a space that may keep the cracks from extending to the finish layer, add an air space for add'l insulation and  I think it may also help the last coat adhere? Can anyone see any big flaws in my idea that I am missing?

Thanks in advance,

SD

ClimbHi's picture
ClimbHi

Dunno about earth ovens, but Scott style masonry ovens use aluminum foil for an isolation membrane between the bricks and the concrete cladding. Depending on how thick your oven is, burlap may carbonize if it gets hot enough and leave a gap that could make things worse.

ClimbHi
Pittsburgh, PA

willwork4SD's picture
willwork4SD

Hi,

Thanks for the comment. I thought about foil, too, but read that it can trap moisture. In a clay oven that would cause problems. They need to breathe.

When I fired the oven up last weekend, the top of the dome got up to 89 degrees F. (Inside the oven, it was >900F) But it is open to the air, and probably still a bit damp, keeping things cooler. It takes a while  for the clay to dry throughout. There is anywhere from 7 to 10 inches of material in 2 layers on there.I think I'll wait a bit longer and keep checking the outside dome temps while firing before making a decision. I guess I'm just hoping to keep the hairline cracks  from affecting the nice, smooth finish coat I plan to apply, complete with a mosaic inlay;-)

When I figure out how to post a pic, I'll do so.

I really wanted to build a brick oven ala Allen Scott, but thought this would be a good first forray into wood fired cooking just to see how I liked it. So far, so good. Thanks again for your input!

SD

ClimbHi's picture
ClimbHi

Maybe aluminum screen then? Might be a bit of a chore getting it to lie flat on the dome, but it's probably do-able and would serve as an isolation membrane much like the burlap would.

ClimbHi
Pittsburgh, PA

PMcCool's picture
PMcCool

Non-combustible and non-rustable.

Paul

ClimbHi's picture
ClimbHi

There ya go! Just make sure that the top coat is thick enough to be self sufficient.

ClimbHi
Pittsburgh, PA

willwork4SD's picture
willwork4SD

like it would work!  If I used a weave that was not real fine and tight, it should allow moisture through while maintaining a little breathing room for the last layer. Thank you both for your ideas. I will update you when I get it done, probably this weekend.

SD

willwork4SD's picture
willwork4SD

This is my oven as it is right now, before the final smooth plaster. (which I hope to apply soon)

The 1st step was a foundation,

I pulled all the stone for the base from the woods in our yard. My little helper is keeping everything on the level.

I used wine and beer bottles to insulate the base below the heatsink and hearth.

Then came the arch and hearth bricks.

And the thermal layer.

We added a permanent roof. I use canvas tarps as walls. They are easy to put up and take down when firing. They protect the oven in windy rain storms and hopefully blowing snow in winter.

Insulation layer completed early June 2011. So far, we have had a few pizza nights and a practice loaf of sourdough. There is still much to learn as far as timing and temps for bread baking, but the flavor of that 1st loaf is very inspiring, it tasted  better than the loaves that come from my gas range. (maybe it was all the hard work that made it seem that way?) I plan to do a few loaves this weekend to try and get a handle on the timing. Sorry the text is all over the place, 1st post w/pics for me;-)

SD