|Monthly Tech-Tip |
The red controller on the right is a Skutt Kilnmaster, the blue controller to the left is an Orton Autofire. As of 2022 both of these are now ancient devices, having been replaced with newer touch panel units. The principle of operation for both is the same: They turn the power on and off in a duty cycle to control temperature rise. A 50% duty cycle, for example, sees the power on for 50% of the time. The length of individual bursts increases with kiln temperature. The controllers monitor a thermocouple in the kiln to determine the length and frequency of power bursts needed. Both of these devices are external to the kilns (but there is a big difference). The KilnMaster controller is attached to the 220V power line and the kiln power line attaches to it (there are heavy-duty electrical relays inside). The blue Autofire controller does not have internal heavy-duty relays or switches, they are in the kiln. The KilnMaster is thus more flexible since it can connect to any kiln, but it is also triple the price. In 2022 the AutoFire now has its own relays like the KilnMaster.
A test kiln is a must for all potters and small manufacturers, even serious hobbyists. Here is why.
In ceramic kilns the firing schedule is typically managed automatically by an electronic controller. But that may not mean that ware gets automatically fired to the correct temperature and atmosphere.
All types of ceramic are fired in a kiln to cement particles together to produce a hard and water and temperature resistant product.