Saturday, March 21, 2009

Voyage of the Great A'tuin... Cob Oven!

Teaching a cob oven workshop in Williams, Oregon.

Local clays and grasses to work with

Urbanite and strange concrete blocks to bury into the foundation.

Making adobe bricks to build up the foundation to a good baking height. I made a trapezoidal form so that we could easily create a 48" diameter circle.

Laying the adobes, with glass bottles inbetween

The insulation layer which will be underneath the baking surface. This layer of glass bottles and sawdust will help keep the heat in the oven from escaping through the mass of the base.

The baking surface made of kiln bricks and a wet sand dome which will serve as the mold for the oven.

After building up the first mass layer and arch for the doorway, we can remove the sand form.

Slip-Straw insulation layer next

about six inches thick

a small fire to speed up the drying from the inside out

Rough sculptural cob starts to form the turtle

Plaster samples to test the effects of our local soil

Plaster over the rough cob form

A test bake

Starting the mosaic

Eric and his oven!

A celestial mosaic on the front of the oven.
The Great A'tuin is holding up the world afterall.

Some more of the mosaic.
Jasmine, the owner's 10-year old daughter helped out a lot!

Monday, March 16, 2009

Earth & Lime Plasters at Aprovecho

Ashley Aymond showing how to earth-plaster over lathe.

Lime plaster samples

Lydia Doleman mixes up the lime plaster

Bio-Char Kiln

Welcome to low-tech charcoal production. You can make an earthen kiln to produce Bio-Char. Using ground charcoal as a soil amendment is proving to increase yeilds and sequester carbon among long lists of other positive benefits. We should all be adding it to our gardens and compost as the ancient cultures of the Amazon did. In the areas of the rainforest where this was practiced, there are still several feet of topsoil, also known as Terra Preta.
Google it if you're interested to learn more.
Now, for the earthen building part, this diagram I created shows the basic layers and features of the kiln and the following photos show how we built one.

We even added a thermal probe to test the temperature fall-off of the kiln and to ensure the quality of our charcoal. In Thailand, charcoal is often used for cooking because it smokes less and also for water filtration. This is an extremely important product in developing countries.

Then we grind the charcoal to get a small particle size.

adding wood vinegar to speed up the activation.

We measured out different ratios to test the effects of Bio-Char on seed germination.

We also planted test plots where we could compare the growth of Bio-Char amended soil and without.

We planted the same plants on each side of the test plot.

There will be an article in Permaculture Activist soon with the results of this study.

Part 8: Finishing Touches

Sculpting the 'giving tree' in Tahn's room.
The luckiest four-year-old ever!

Trim detailing with burlap stapeled to the frame for a
mechanical connection with the plaster to wood.

Lime in the shower area.

Burnishing with balled up plastic bags to get a super smooth surface.

Reclaimed tile set into an interior arch sill.

The stairwell niche.

Making clay paints with tapioca starch paste.

Beautiful arch detailing so that you can still tell they were made from adobes.

A clay-paint mural I did in the entryway of Peggy and Jo's new home. It is based on a Thai proverb about the rice in the moon and the fish in the pond.