Homemade Electric Kiln
Kiln building is a great do-it-yourself project. A kiln is basically a furnace with heat controls to adjust temperature. The components of a kiln include the firebox, lid, the heating element and shelves to place the pottery on as it dries.
When building an electric kiln, the main decisions to make are the kiln's design, size, location and style, either front- or top-loading.
Kiln Design and Plans
When deciding on kiln size, consider how often you fire. Too large a kiln will waste energy if the kiln isn't full when fired and too small a kiln will leave you frustrated on having to wait while pieces fire. Because the heating element is electric, consider the additional energy expense required for firing the kiln. Another consideration is whether to build a front- or top-loading kiln. Both kiln styles require the user to reach and bend to fill it and, in the case of the top-loading kiln, users have to be taller than the kiln itself to place pottery inside. Several books focusing on electric kiln building plans are featured on the Robert Compton Pottery website, including “The Kiln Book” by Frederick L. Olsen and “Kilns: Design, Construction and Operation” by Daniel Rhodes, two well-known kiln builders. Always follow proper safety guidelines when working with electricity.
The firebox is the oven body and is constructed of heat-resistant bricks known as firebricks. Depending on the size and location of the kiln, you can choose from two different types, according to Sheffield Pottery. You can use soft bricks to construct indoor kilns and hard bricks for outdoor and heavy-duty kilns. Hard bricks are further differentiated into high-heat, super and alumina, which is used for commercial drying applications. Commercially made electric kilns are constructed of firebricks stacked on top of one another without mortar and then surrounded by either bands or sheets of metal and fastened. This is a design possibility for the home kiln builder, however if you don't use metal to encase the brick, use mortar specifically designed for use in high-heat applications to cement the firebricks to each other. You'll also mortar together the firebricks used to construct the lid and the bottom slab.
The heating element is the most important part of a kiln. In an electric kiln, heating elements made of wire heat the kiln to firing temperatures. Heating elements are available in a kit dependent upon the size of the kiln. You'll also need controls, either manual or electronic, to regulate the temperature inside the kiln. Three-position switches—off/low/high—are used in manually controlled kilns. Sophisticated control panels are available for electronic temperature regulation with preset programs such as delayed start and automatic shut-off.