Monday, May 5, 2008

cob ovens on trailers

"I was wondering if you might have any info or resources for cob oven on trailers?"

This is without doubt THE most frequent inquiry I get. It's also a large part of why I decided to put up a blog. So here's my thoughts and experience, over and above what's already in Build Your Own Earth Oven:

I wouldn’t try to put a cob or earthen oven on a trailer myself. I do know of one guy who did — he had to do repairs on the oven before the year was out — but I haven’t heard from him since, so don’t know the whole story of his oven. Maybe it's doing just fine. It's hard to imagine that unfired earth would be able to withstand prolonged exposure to road vibration without serious cracking and ultimate failures.

The only oven I did put on a trailer was made of lightweight, hi-temp cement, as described in the book. I’ll refer you to that and Dan Wing’s article about trailers for ovens, which is on handprintpress.com.

Other than Peter Schumann's site-built, stacked-brick ovens, which I only know by the reputation of his bread and puppet theater, I haven't heard from anyone who has really tried to make simple, site-built temporary, wood-fired, masonry ovens. I've seen one in Mexico, mortared with mud so that it could be taken apart and moved to another town for another festival.

There are myriad other ways a person might build a quick oven, from simple (stacked bricks) to complicated (pre-cast, fitted pieces of fired clay (or hi-temp refractory cement) that could be constructed into a shell over a brick hearth). I would think that just about any one of these options would be much cheaper than building a road-worthy (and safe) trailer.

I'd love to hear from folks who've got experience they'd like to share on this one, especially anyone with photos of Mexican festival ovens.

1 comment:

CCAT (Campus Center for Appropriate Technology) said...

I agree with you. I have not seen a successful earthen oven on a trailer. I have seen many different brick ovens with a cement/stucco like plaster that look very beautiful and organic in shape that survive may years on trailers. I do believe also that some re-bar or other steel is used in the process as well. Perhaps an air ride equipped trailer could haul an earthen oven around, but it may require using some materials with a greater tensile strength like sticks or bamboo inside the layers of clay and sand.
Someone should give it a try and see how it holds up. We could potentially be underestimating the strength of a good clay sand straw mixture.
Thanks for the post,
CCAT