Electric Hobby Kilns: Some Recent Advances You Should Not Ignore
Section: Firing, Subsection: General
Description
Electric firing is undergoing a renaissance among potters because of changing attitudes and new equipment.
ArticleIn the past electric kiln users felt somewhat like second class citizens in a ceramic community that idolized high temperature gas firing. While it is true that exciting developments in gas kiln equipment have made this medium even more compelling, the electric kiln itself has undergone a bit of a renaissance recently and most of the cons have been erased. Here are a few examples:
Electronic controllers: Almost all kilns have them now. If you don't have one get one. Case closed. Electric firing is about consistency and control and these devices take that advantage much further. They work reasonably well and element life is longer (much longer the lower you fire). Multiple thermocouples also enable some controllers to even out the temperature gradients in the kiln. Crystalline glazes for example were once the domain of a select few, but now they are simple because of these devices.
ITC: This coating material can be applied to elements and the insides of kilns to give electric kilns better durability and economy. ITC coated elements last many times longer and they can withstand reduction firing!
Electric Reduction: Nils Lou, author of "The Art of Firing" has done hundreds of firings using a simple bunsen burner under his ITC-coated electric kiln. It works and it works well.
Ventilation Systems: These not only make kilns safer to use but they introduce draft, a key to improved fired results (if the interior of the kiln can be kept at even temperatures throughout). When products of decomposition are removed quickly during firing (especially carbon, sulfur) results are much better and problems are fewer.
Elements and configuration: High quality electric kilns for industry have always been available and their element mounting systems are far superior to the way electric hobby kilns work. Hobby kiln element mounting has not really changed that much however the kilns have become more modular and elements are being mounted in the floor and lid in many models.
Of course the proper functioning of these kilns depends on maintaining them well, especially the elements and the thermocouples. It is very common to find badly decomposed thermocouples and potters wondering why their glazes do not look right.
However there is a need for an accompanying renaissance in the thinking of potters to really exploit these kilns. Electric kilns really shine at low to medium temperatures where it is possible to create high strength stoneware bodies (and therefore it is unnecessary to fire at high temperatures). "Stoneware" is simply dense and strong non-pourous ceramic. It is no longer synonymous with cone 10, it can be made as low as cone 1. However it is more difficult to create glazes that are non-leaching, hard and uncrazed. Matte glazes are easy to make at cone 10, but not so at medium temperatures, some key mechanisms of the high temperature mattes do not exist at cone 5-6, for example. Glazes at high temperature have lots of clay and the slurry suspends well, but at middle temperatures more flux is needed, that means less clay and more problems with the slurry and application. Materials that melt well a high temperatures (e.g. dolomite, talc, feldspar, whiting) melt poorly or not at all at middle temperatures. Boron is the king of fluxes at medium temperatures, glazes need it to melt. It is sourced from frits and natural boron materials like gerstley borate, ulexite and colemanite. Recently there has been a proliferation of books on cone 6 electric firing and we have been deluged with middle temperature glaze recipes. But that does not mean that these glazes are good or easy-to-use. Understanding some of the chemistry and the materials will give you more control to create what you want and what you need to really make efficient use of your electric kiln. Out Bound Links
In Bound Links
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Electric Hobby Kilns, How Good Are They? Electric hobby kilns are certainly not up to the quality and capability of small industrial electric... - (Project)
Ceramic Firing Schedules
Fast firing is almost universal in most sectors of... - (Glossary)
Controller
An electronic device attached to a kiln. Controlle...
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