Things You'll Need
Copper sulfide (optional)
Corrugated iron sheet
A wood fire has been the principal heat source for kilns for thousands of years. The most primitive kilns were simply a pit in the ground with a fire built on top, but using brick helps to insulate the kiln and achieve higher firing temperatures. Brick kilns are made in hundreds of different designs, some very complex, but a simple, mortar-less brick kiln using wood fire is easy to construct.
Lay a 3-foot square of bricks on the ground, for the floor of the kiln. Make sure that the area is flat, devoid of vegetation and at a distance of at least 15 feet from any buildings.
Build the walls of the kiln by laying bricks one on top of the other, until a 3-foot cubic brick box is formed. Leave out a window of around 3 bricks from the top of one side of the kiln wall for a through-draught vent.
Fill the bottom of the kiln with around 5 inches of sawdust and place the pottery pieces in the sawdust. Sprinkle the copper sulfide over the pots if desired—this is purely aesthetic, as copper sulfide helps create different color patterns on the pottery.
Scrunch newspaper and place it in a layer on top of the pottery, then fill the rest of the kiln with firewood, being careful not to disrupt the brick kiln walls.
Light the fire when the kiln is full, making sure it catches all the way down. Add more wood as the fire burns down until a good blazing fire is achieved.
Cover the top of the kiln with the corrugated sheet, weighing it down with some bricks placed on the sides of the top.
Let the kiln burn for around 12 hours, or until it burns itself out. Unpack the kiln only when the fire is completely out and has cooled sufficiently.
Placing organic material like leaves, fruit peel or other metal oxides and sulfides around the pots helps to create different patterns and colors on the fired pottery pieces.
Kilns reach very high temperatures (in average of 1,500 degrees F) so keep pets, children and inebriated individuals well away from kilns as they burn.
Check if kilns are allowed in your jurisdiction before building one.