A kiln is perhaps the most important piece of equipment for the ceramicist, amateur and master alike. However, Even small electric kilns can cost hundreds or thousands of dollars, leading many hobbyist potters and ceramic artists to build inexpensive gas powered kilns. These kilns are small, lightweight and can achieve temperatures of up to 1093 degrees Celsius, making them ideal for Raku and other high-temperature techniques.
- Skill level:
Things you need
- Large steel rubbish bin
- 2-inch thick ceramic fibre blanket
- Large propane tank
- High-pressure propane regulator
- Venturi burner
- Tin Snips
- Electric drill
- 1-inch hole saw bit
- 1/16-inch drill bit
- Sodium silicate high-temperature caulk
- Fireclay or Raku clay
- High-temperature wire
- Leather gloves
- Dust mask or filtered respirator
- Needle-nose pliers
- Heavy-duty scissors or shears
- 2 firebricks
- 4 cement breeze blocks
- Spark striker
Use your 1-inch hole saw bit and electric drill to bore a hole through the side of your rubbish bin about 3 inches up from the bottom. Using your tin snips, cut around the hole and enlarge it until it is slightly larger than the diameter of your Venturi burner's torch head.
Bore a hole through the centre of your rubbish bin lid with your 1-inch hole saw bit to act as the chimney. You may need to remove the metal handle with your tin snips before drilling the hole. Cut around the hole with your tin snips and enlarge it to about 2 inches in diameter.
Create a handle for the top of the kiln by drilling two, 1/16-inch holes into the edge of the lid across from one another. Bend a piece of thick wire into a half-circle, large enough to connect the two holes. Bend in the last inch of wire on both sides at a sharp angle towards the centre of the half-circle. Pop the bent ends of the wire into the holes on either side of the lid, creating a thin wire handle.
Preparing Your Trashcan
Put on your leather gloves and respirator and remove your ceramic fibre blanket roll from its packaging. Place your rubbish bin on op of the ceramic fibre blanket and the bottom of the rubbish bin as a template. Cut out the circle with your scissors and place it inside your rubbish bin to insulate the bottom.
Unroll a large section of ceramic fibre blanket and cover the sides of the rubbish bin on the inside with at least 1 layer of material. If you are using 1/2-inch ceramic fibre blanket, you will need 2 layers.
Cut several three-inch sections of high-temperature wire and bend them in half at the middle. Drill two holes about half an inch apart in the side of your rubbish bin, four inches down from the top of the rubbish bin. Take one of your bent pieces of high-temperature wire and thread the two ends through the ceramic fibre blanket on the inside of the rubbish bin and out through the two holes in the side of the can, effectively pinning the ceramic blanket to the inside. With your needle-nose pliers, grip and twist the ends of the wire on the outside of the rubbish bin to tighten the hold. Snip off the ends or bend them down to prevent cuts and scratches.
Repeat this process until you have eight pins evenly spaced around the body of the rubbish bin, holding your ceramic blanket firmly in place. Turn your rubbish bin upside down and pin the piece of blanket on the bottom in place as well.
Cover the area of exposed wire with fire clay or furnace cement to protect the exposed portions of high-temperature wire on the inside of the kiln from extreme temperatures. Allow the cement to dry for at least 24 hours before firing your kiln to prevent cracking.
Lining the Kiln
Place your dustbin lid on top of an unrolled section of ceramic fibre blanket. Trace around the lid and use it as a template to cut a circle large enough to cover the entire inside of the lid. The lid will need to be double insulated to prevent heat from escaping, so cut another circle of the same size out of ceramic fibre blanket.
Pin the two layers of ceramic fibre blanket to the inside of the rubbish bin lid at the four cardinal points around the chimney hole, using your electric drill and sections of high-temperature wire. Try to pin closer to the edge than the centre to ensure even coverage.
Use fire clay or furnace cement to protect the exposed wire on the inside of the kiln lid and allow to dry for 24 hours before firing to prevent cracks.
Insulating the Cover
Use a pair of scissors to cut out the extra ceramic fibre blanket that is blocking the chimney hole in the top of the lid and the burner hole in the side of the rubbish bin.
Arrange your four breeze blocks so that they form a flat, level platform outside or in a garage, in an area away from any flammable or explosive material. Place your rubbish bin on top of the breeze block platform.
Lay several firebricks in the bottom of the rubbish bin to form a shelf for your clay pieces. Connect your Venturi burner to the hose on your high-pressure regulator and attach the regulator to your propane canister.
Arrange your Venturi burner so that the torch head is positioned half an inch outside the burner hole in the side of your kiln so that the jet of flame will point directly into the centre of the kiln.
Turn on your propane and slowly increase the PSI until you reach the recommended amount for your Venturi burner. Strike a spark in front of your Venturi burner's head with your spark striker to light the flame. Adjust the propane until you have a nice cone-shaped jet of flame firing into your kiln through the hole in its side. Place the lid on top of the kiln and allow kiln to slowly heat up. Once the test firing is complete, allow the kiln to cool down before firing clay.
Setting Up and Firing Your Kiln
Tips and warnings
- You can use specially designed ceramic buttons instead of pieces of high-temperature wire to pin the ceramic fibre blanket to the inside of the dustbin. These typically last longer and have better thermal insulation properties.
- Gas powered kilns can achieve temperatures of up to 1093 degrees Celsius. Use all possible precautions when working with high temperatures. Never touch any part of the kiln during operation, except for the wire handle, and then only wearing leather gloves.
- Ensure all gas fittings are tight and free of leaks. Improper storage and use of propane can lead to explosion, injury or death. Read all safety instructions for your Venturi burner, pressure regulator and tank before attempting to use your kiln.
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