For example, if you wish to fire 4 pieces at once that are each 1 ft (0. 30 m) tall, 1 ft (0. 30 m) wide, and 1 ft (0. 30 m) long, multiply 1 ft (0. 30 m) by 1. 5 and the combined width and length (4 ft (1. 2 m) and 4 ft (1. 2 m)) by 1. 5 to determine the depth of the kiln. If you’re producing many pieces, consider putting multiple shelves in your kiln. Using shelves, you can build a taller and narrower kiln that can hold more pieces. Depending on the height, you may need to build a metal frame to bolster the walls. [2] X Research source
For example, if your kiln’s interior was 9 ft (2. 7 m), add either 3 in (7. 6 cm) or 2. 5 in (6. 4 cm) (depending on which size brick you bought) to determine the exterior height.
If you estimate your kiln’s interior length is 5 ft (150 cm) and interior width is 9 ft (270 cm), by adding 8 inches to each you’ll need to build a kiln 5. 66 ft (173 cm) by 9. 66 ft (294 cm).
Make sure you purchase a firebrick with the same dimensions you used to calculate the volume.
If you want to build a cylindrical kiln, examine the land you have available to see if you have the space to build one with the same interior depth as a square or rectangular kiln. [7] X Research source
When clearing the space of vegetation, make sure you pull up any plants or weeds by their roots. If the space is not wide or long enough for your proposed kiln, consider reducing the length and width and increasing the height proportionally by adding kiln shelving.
You can typically buy firebricks for between $0. 50 and $0. 75 per brick. Firebricks are usually sold in pallets, often in multiples of 100 or 1,000.
These bricks will not only serve as your base layer, but also a shelf for your pottery.
For added stability, add each layer of bricks on top of the layer beneath it such that each brick’s end is perpendicular with the center of the 2 bricks underneath it. Repeat this process until you have built the kiln’s walls to their required height. When you have completed laying all the bricks, go to the wall that faces the wind direction. Remove a section of bricks 3 bricks high from the top of that wall. This gap will serve as your vent, allowing the smoke from the fire out and keep the kiln from overheating. [12] X Research source
If your sheet is made of cast iron, it is prone to rust easily. Make sure you remove it from the kiln and cover it when not in use to prevent damage from rain.
If your kiln includes multiple levels of shelving, go to the kiln’s opening and place approximately 4 in (10 cm) of sawdust on each level of shelving.
Individual pottery pieces should not touch each other. If you are unable to load the pottery without some pieces touching, place half of them at the kiln for an initial firing. Fire the rest later.
As you grow more experienced with your kiln, experiment with different types of sawdust shavings, as well as where you place the sawdust, which will result in different finished effects.
When stoking the fire or otherwise approaching the kiln, use heat-resistant gloves and protective gear, such as goggles to protect your eyes from the smoke. As the fire consumes the sawdust, the upper half of the kiln will begin to cool. The slower the fire burns, the darker the pottery will be. To lighten the pottery, stoke the fire and add additional fuel – newspaper and wood – if the fire appears to be burning slowly.
If you’d like your pieces to have a matte – or non-glossy finish, do not apply wax. Painting your pieces with oxide stains is the best approach to preserving your matte finish.
