While using a wood-fired kiln means sacrificing some of the precision and simplicity possible with an electric or gas kiln, it can be a novel and worthwhile experience. Wood firing clay is an ancient, basic approach to pottery that has been used successfully for thousands of years by cultures across the globe, and it is still a mainstay of many artists today. Making a small wood-fired garden kiln is not difficult or expensive, and it offers a great way to begin experimenting with wood firing on a small scale.
Choose a flat spot free of vegetation and far (15 feet or more) from any trees, bushes or buildings. Set bricks in a row to create three sides of a square the right size to support your metal grate. Then set a second layer of bricks on top of the first.
Place the metal grate atop the two layers of bricks.
Extend the height of the three kiln walls by two more layers of brick (above the grate).
Set your iron sheet onto the bricks diagonally, so the walls support its corners rather than its sides, to create a kiln shelf. Set strips or scraps of metal onto the bricks not covered by the sheet to create an even surface for your next layer of bricks.
Set bricks onto the kiln shelf in a roughly circular configuration, leaving a large open space in the middle.
Repeat Step 5 several times, but make each ring of bricks somewhat smaller so that the kiln narrows as it rises.
Lay strips or scraps of metal over the top circle of bricks to create a partial roof for your kiln. Leave an opening near the middle to serve as a chimney. Place your firewood on the grate, set your pottery onto the kiln shelf and fire up your kiln.
Never leave a hot kiln unattended, and always have a fire extinguisher or similar equipment on hand. Look up any local laws or zoning regulations that may relate to building fires or operating outdoor kilns.