Clay Ovens Introductions Discuss Clay Ovens in the Good Background Information forums; Originally Posted by Archena Hi, I love the pics. Thanks for sharing! One question though, why two openings? I assume ...

[luca]

Originally Posted by Archena

Hi,

I love the pics. Thanks for sharing! One question though, why two openings? I assume the wooden thing in the background is some kind of roof that you put over it. Are you using a tarp as added protection? (Okay, so that was two questions...).

Note to self: make sure to use oven regularly! Bugs are icky!

The side opening was an experiment which didn't work (the oven's air flow was awful and starting a fire was tough. The air has to make a kind of circular pattern which is encouraged by the domed roof, but this doesn't happen if the air flow is perpendicular to the domed roof rather than in line with the dome). So I simply closed it up with more clay, and drilled some holes in the end as you can see in the pictures, to make a new opening. This works much better!!! As for the roof, it is OK but has blown off and is subject to scorching when the oven is running, so I have since changed to a tarp cover; hence the bug problem.

[luca]

Thanks for the idea; I'll definitely look into it. My only hesitancy with any cement product over the clay is that I've read that the oven has to "breath," and it certainly expands/contracts with use, so I'm afraid any inflexible coating may create mechanical problems (e.g. cracking during firing, which will then be inaccessible from the top). Back to the stucco, what would you recommend for the interface between the stucco and clay surface? (I would think the movement issue could be partially remediated if there was some space between the two materials that allowed some minute movements when the oven is running full tilt...what do you think?).

[Archena]

Um, I’m not sure if you mean me or RT. I was the one that mentioned papercrete a while back, which is a concrete product. But I had it more in mind for an enclosure rather than a coating. Obviously, my plans aren't terribly well thought out in the enclosure department…

[Frances]

Originally Posted by luca

I've read that the oven has to "breath,"

I think I would hesitate to put a cement product over a clay dome before doing some serious reading up on it.

I have heard that clay can be a brilliant product for the inside of houses... but only if they are not hermetically sealed (as many more modern buildings are), exactly because the clay can't breathe. Our cellar has wooden boards over clay on the floor - I don't know of any reason why this should be superior to a cement floor, but I do know you have to be careful converting/insulation projects, to take breathability into account.

It also strikes me that if you made a second dome over the first with a gap between the two, it'd be a really cool place for creepy crawlies to get in and virtually impossible to get them out. I think you would want to keep access to the outside of the dome. Maybe .

Sorry, don't want to be overly critical here, just trying to think this through. Maybe a more substantial shack built over the oven would be a better bet after all?

How often does the oven go without firing? Because if you could make sure to fire the oven up every couple of weeks even it you don't really need it, that would keep pests away, wouldn't it?

[Tim F]

How about if you used a mixture of clay and vermiculite for the insulation? And then for waterproofing, use milk paint with linseed oil. I haven't tried this yet but I have read that milk paint made with linseed oil is effectively waterproof. There are some other recipes here: Homemade Milk Paint Recipe - Real Milk Paint ®

[Archena]

Vermiculite is made of pellets right? My guess is that any mixture have enough vermiculite to actually provide good insulation would also have problems with cohesion. You couldn't use it in the interior it all, or in any part that's likely to be bearing weight, because the vermiculite would seriously compromise the material strength.

The milk paint with linseed oil sounds interesting. Both milk paint and whitewash have to be reapplied periodically no matter what it is you're applying it to. If I'm not mistaken, and it's early in the morning so I very well may be, whitewash is traditional for cob. If you look at pictures of 15th century houses, some of which are still standing and in use, they usually appear to be whitewashed. I know lime is one of the components of the mix so that would be whitewash, correct?

One of the things that I’m intending to do to test some of this stuff out on it to make very small ovens, and try it out that way. I saw a website somewhere. I’m not my desktop so I probably can’t find the link right now but they made one very small oven big enough for a muffin. I figure I can use concrete pavers as bases and see how things work out. I figure it’s a lot easier to find out at small-scale than it is at full scale.