Why Schedule the kiln to room temperature? The kiln will cool slowly enough at the
final stages.
How do you know?
Relatively large thick pieces need slow rates of cooling
below 370°C. Complex tack fused
pieces require slow cooling rates as well as the long annealing soaks. These
required rates of cooling may be slower than your kiln’s unpowered rate of cooling.
This means you need to know the natural cooling rate of your
kiln from 370°C down to room temperature to be sure you are cooling at a
suitable rate. The method described in this blog post gives you information on
how to calculate the natural cooling rate of your kiln.
I program my firings to about twice room temperature. Yes,
the kiln does not turn on much during that time, but when I crack my kiln
open to speed the cooling, the switching on of the relay tells me I am cooling
faster than programmed, and I can reduce the size of the opening to avoid too
rapid cooling of the piece.
The following chart is a way to assist in recording your
kiln’s unassisted cooling temperatures against time to give you the natural
cooling rate at various temperatures.
Kiln Name: | Cooling Rate | |||||
observ'n | Time (hr:min) | Temperature | Difference | rate/min | rate/hr | |
1 | : | Time (mins) | Temp. | =temp/mins | .=temp/min*60 | |
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