Primitive Technology: Fired Clay Bricks

Digging clay for brick mold Crushing old pottery for grog Mixing grog into clay Forming the brick mold, adding a tab for lifting It's 25 cm by 12.5 cm 25 cm x 12.5 cm x 6.25 cm Into the kiln Fire a large pot at the same time (so as not to waste fire wood) Cover with old pottery Fire sticks The pottery itself must glow incandescent red or hotter to be properly fired Fired mold ready to make bricks Digging a clay pit Clay from the creek bank Into the pit Water Treading clay Picking out stones Forming bricks Sprinkling wood ash down to stop the bricks sticking to the ground Tip: soak mold in water/wood ash solution so the clay slides out of the mold easily It rained a lot during this project, the hut was essential in keeping the bricks dry Staking bricks around fire to dry further Cutting some bricks with a bark string to form half bricks Drying bricks out with help of forge blower Turning bricks so they dry faster Stacking next lot around the fire This is only to dry them out.

Firing them properly will come later Bricks visibly drying Mining More clay (stop motion for dramatic effect) Collecting standing dead wood Breaking up fire wood Assembling small brick kiln for firing experiment Kiln is 50 cm tall and inside is a 25 cm square cross section Note the brick ledges, this is what the bricks to be fired will sit on (instead of a grate) Only 4 bricks will be fired, I tried 6 but it didn't let the flames pass through enough.

Always ensure at least a fingers width between bricks. Flames moving between bricks nicely At about 30 minutes I added bricks to the top to help keep the heat in while still letting the draft flow through Too much wood chokes kiln of air, cooling it. To little, and the kiln cools down due to lack of fuel. Just watch the flame and the pottery glowing and adjust as necessary.

Adding more bricks to keep the heat in while allowing a gap for the flames to come through Clay must glow incandescent red or hotter, otherwise it will dissolve in water afterwards. Closing up kiln. Total firing time: 2 hours Opening the next day when cool 4 Fired bricks Submerging brick for water test 15 minutes under water Brick passes water test intact. An un-fired brick would have dissolved in water Mold and fired brick.

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