Posted by joewizard on January 02, 19100 at 06:27:28:
In Reply to: How about a ceramic kiln for burnout? posted by Rob Frink on December 30, 1999 at 17:38:00:
Would I pay $450 for a small electric ceramic kiln, without at least a high limit temperature control, and use it to burnout? Nope. First i'd call a ceramics/pottery supply shop. They probably have a bulletin board plastered with anxious kiln-sellers. Large, worn out industrial models often rust away at the junk yards.
Ceramic kilns are built to achieve a far higher temperature than burnout needs. Walls are thicker than necessary, and the interior is correspondingly smaller for the floor space it takes up. Top loaders are uncomfortable. Imagine having a top loading oven in your kitchen. If you stack molds, you may need shelves, and in any case you cant peek in and see the lower molds or get to them easily.
My experience regarding nichrome elements: Sometimes elements burn up fast. Sometimes it seems that no matter what happens to them, the elements survive. I built a small electric kiln for testing clay formulas about 12 years ago. Do everything from burning out small plaster/wax molds to melting silver/gold/bronze in it. Several times smoke bellowed out of the vent. Lord only knows what chemical reactions were happening inside. About a year ago a clay body test piece melted at 2400F (no auto temperature control on this one), filling the lower grooves with a black rock-like formation. Instead of chipping it out, and destroying the walls of the kiln, i just kept running it. So far, the original elements live on, partially embedded in a layer of granite.