A kiln is a versatile piece of equipment in a studio whether you want it for ceramics, glass or metal clay. However, the prices can range for more than $300 for small table top models to thousands of dollars for large capacity kilns. Because it heats cleanly and efficiently, natural gas can be a cost-effective option for a kiln. Although building a natural gas kiln may sound complicated, it can be done safely and inexpensively.
Assembling the Kiln Box
Assemble an angle iron frame for the size kiln and door that you want. You can also check with your local vocational or trade school for a list of welders willing to do small projects. Once you have your frame, position it in the area that you'll be building the kiln. Once you begin building, you will be unable to move the kiln.
Lay the layer of concrete block for the base of the kiln, and layer the patio blocks on top.
Soak the bricks with water as you work so they don't dry the mortar too quickly. Drill a 1/2-inch hole in one brick to insert the thermocouple. Drill openings or cut the end of of two bricks for the propane burners. The bricks for the burners should be placed near the bottom of the kiln at opposite ends. Consider ease of access for maintenance when placing the bricks.
Lay the bricks on the base on top of the patio blocks, applying a thin coat of mortar on the edges as you work. Cut the bricks to fit with the brick saw.
Build up the walls with the firebricks and mortar with the corners fitting against the frame.
Place the sheet metal arch on top of the walls with the edge extending slightly so that you can take it out after the bricks are laid. You'll remove the sheet metal once the mortar is dry.
Install a commercially made vent in the kiln according to manufacturer's instructions, or make your own out of more firebricks and mortar. It will resemble a small chimney with the opening at the bottom and the vent rising above the kiln. If you are building outdoors, you won't need a hood, but you will if your kin is indoors. You can either buy a commercial hood or have one made at a local sheet-metal shop. Indoor kilns must be vented outdoors.
Layer the firebricks at the edges, and work toward the middle. When the mortar has set, carefully work the sheet metal arch out from under the bricks. The weight of the bricks hold the roof steady.
Attach the hinges for the door to the kiln. Drill into the firebricks with an even pressure. Assemble the door with firebricks, and attach to the kiln with the hinges.
Connecting the Natual Gas
Securely fit the burners into the pre-cut bricks.
Follow the manufacturer's directions to attach the burners to the copper pipe and shutoff valve. Use the T-valve to spit the line for both burners.
Insert the thermocouple into the small drilled hole, and install any features that you want.