Pottery is one of mankind's oldest crafts, and the development of pottery has gone hand in hand with the development of the kiln. A kiln is similar to an oven, but one which reaches extremely high temperatures---sometimes over 1,093 degrees C. The earliest kilns were a simple pit with a fire in it, but over time brick kilns developed along with more complex chamber designs. This led to the gas- and electric-fired kilns of today. While it is easier to control the temperature these modern kilns, many potters still prefer to use and make wood-fired kilns because of tradition, and the effects they create on the pottery.
Dig a square hole, around 3 feet wide and 1 foot deep for a small kiln, otherwise as large as you require. Make sure the area you choose is free from vegetation and at a distance from any buildings. Confirm that there are no fire restrictions in the district.
Place the level on the floor of the hole, and use it to make sure the floor is even, adjusting where necessary.
Place a single layer of firebricks, tightly packed, over the floor of the hole. This will be the base of the kiln.
Lay the walls of the kiln using firebricks in the typically interlacing pattern of brickwork. The first foot or so will be against the hole walls, but once you get above the hole walls, leave a ¼ inch space between each brick for ventilation. Continue until the kiln walls are around 3 feet tall altogether,1 foot tall inside the hole and 2 feet tall above it.
Sprinkle 5 inches of sawdust over the bottom of the kiln, then settle the pottery pieces into the sawdust, the largest and heaviest first.
Cover with another layer of sawdust, and more pottery pieces if any remain. Continue in this way, adding sawdust and pottery pieces, but do not fill the kiln up entirely. Leave at least 10 inches from the top of the kiln free.
Layer the firewood and kindling on the remaining space, setting it alight with the matches. Make sure that the fire catches all the sawdust down to the bottom. Add more firewood as the fire compresses, then cover the kiln top with the metal sheet.
Let the fire burn for around 12 hours, adding wood as necessary, but it should continue to burn on its own for around this long. Unpack the kiln when it is thoroughly cooled.
Mason work kilns can be constructed on a permanent site---these generally have a beehive-shaped roof and a fire box underneath the chamber where the pottery sits. Add organic matter, such as leaves, fruit peels or even silicone dioxide or red iron oxide for different effects on the pottery.
This type of kiln is not suitable for glazing, rather for earthenware pieces and unglazed pottery.