Without kilns there would be no ceramics. Since the very beginning when primitive man discovered the soil around a fire changed to rock, learning how to contain the heat and control it has been an ongoing endeavor. Many types of kilns have been constructed over the millennia and today we’re fortunate to have such a wide selection to choose from. You can choose the type of kiln atmosphere you want (oxidation or reduction), the type of fuel you want to use (oil, gas, electric, or wood) and maybe even the special surfaces you want (salt, soda, raku, or pit). This Ceramic Arts Daily guide to types of ceramic kilns will help you make all these decisions.
Here’s an excerpt from A Guide to Ceramic Kilns: Choosing the Right Kiln Firing Method and Design For Your Art:
Purchasing a Commercially Made Electric Kiln
by Richard Zakin
Most electric kilns are purchased completely assembled and ready to plug in. Their design and construction vary a great deal: it is no easy matter for the ceramist to make an intelligent purchasing decision.
At one time most electric kilns were front loading. Kilns of this design are highly durable for they must be heavily braced. This makes them very heavy and bulky. While frontloading kilns are expensive, this design results in a kiln that lasts a long time and can be loaded quickly and easily. Toploading electric kilns have been very popular for years because they are relatively inexpensive. These kilns must be carefully designed for they are subject to mechanical and heat stress, particularly in their roof and hinge areas. If you choose a top loading kiln, make sure the roof is replaceable. The flat roof of a top-loading kiln will eventually crack under the stress of normal use.
The roof hinges, also points of stress, should be designed with strong elongated arms to keep them away from the heat path. Many newer top loading electric kilns are segmented. The electrical connections between each segment can be a source of real problems. Look for connections made with industrial grade cables which can withstand the stress that results when the heavy segments are assembled and disassembled.
The gutters that hold and support the coils should be deep and set at an angle to hold the coils securely. The coils should be pinned to the soft brick with refractory metal pins to insure that they will not come loose and sag during the stress of the high fire. The coils should be made from an alloy that resists high temperatures (such as Kanthal A1); they should be easily replaceable and fairly thick (thin coils burn out very readily), and should be consistently wound to avoid hot spots. The switches, wiring harness, and connecting wires should be heat resistant and of the highest quality. Connections to the power source should be secure: a poorly connected coil will soon burn out. The insulation should be effective and durable.
Look for kilns that fire evenly. Floor-mounted coils help keep an even heat throughout the kiln. They add to the expense of the kiln but are a mark of a professional design. Computer-controlled zone firing has proved very effective in assuring an even firing. Each zone is furnished with its own pyrometer and the computer is programmed to direct current to those coils that need it most. Originally computer control was envisaged as a way to automate the firing. An even firing was an unanticipated benefit.
Electric kilns are high current devices and they require special, high quality, high capacity fuses, cables, and outlets. For the installation of an electric kiln there is no substitute for the services of a qualified electrician.
|A Guide to Ceramic Kilns: Choosing the Right Kiln Firing Method and Design For Your Art also includes the following:
Ceramic firing can be done with two types of kiln atmosphere, oxidation or reduction. The one you choose for your own work determines the type of kiln you need.
Certain kinds of visual effects can only be produced with fuel-burning kilns. Find out why you might consider a wood kiln or using oil and gas as fuels, or maybe you to learn more about salt and soda firing.
Potters use electric kilns more than any other type of kiln. They’re easy to operate and you can choose between many commercially made models, including small test kilns and front loading varieties.
by Hal Frenzel
Regardless of your firing atmosphere, efficient combustion can save money and reduce your carbon impact.
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