2013-06-13 / Schools

WRHS students build ‘antique’ cobb oven

Cameron Sullivan puts in one of the first pizzas. 
Joyce Roberts photo Cameron Sullivan puts in one of the first pizzas. Joyce Roberts photo Just outside the high school is a primitive looking structure, made of a red brick base with a round adobe top. It’s called a cob oven, and its design is many centuries old.

How this cob oven made it from drafting stage to build out is all new, however, since it is this year’s project by the students enrolled in the Computer Aided Design and Computer Aided Machinery (CAD/CAM) class taught by technology education teacher Greg Chandonnet.

A cob oven is an earthen oven used outside for cooking virtually any type of food.

First step of the process was designing and building an oversized wooden pallet that would support 1500 pounds. Brick retaining wall block was used for the oven base. To eliminate the possibility of burning the wooden pallet, two layers of empty glass bottles were used as a thermal break between the pallet and the base block. Sand was packed between and above the bottles for insulation.

A layer of firebrick was laid for a cooking base and two cob oven domes – inner and outer- were constructed over a temporary sand mold. The inner dome was made of industrial grade refractory cement called heat Cast 40, donated by Robert Rucker of CMS Industries. The outer dome was created from cob, a mixture of clay, sand and straw. The oven was then left to draw for two weeks.

Part of the design consideration for the cob oven was that it has no chimney, so the door has to be sized to allow smoke to exit, while heat remains trapped inside.

Like a wood burning pizza oven, the cob oven is heating by building a fire inside.

Oven temperatures can rise as high as 450 degrees, students learned, and will cook a small pizza in less than 10 minutes.

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