How do I program a firing schedule?

[Liane]

Hello All,

I have a kiln full of goods and I want to fire it. I am a potter and have been teaching myself how to fire my kiln. So far I have been using the pre-programmed firing schedules. I now want to try a slow cooling schedule.

My kiln is a Cone Art and my controller is a Bartlett. I have the firing schedule that I want to apply and I have a simple example of how to program a firing schedule with the Bartlett - but I am confused as to how to use their "9999" cooling rate code. Their example shows using "9999" at the end of a sequence but I want to use it in the middle of a sequence.

My Cone 6 Glaze Firing program  that I want to use:

100 deg/hr to 200 deg

350 deg/hr to 2000 deg

150 deg/hr to 2185 deg hold 15 mins

500 deg/hr to 1900 deg ***

125 deg/hr to 1400 deg

allow kiln to cool naturally to room temp

*** It is this stage that I don't know how to actually enter the values into the Bartlett. The notes in the Firing Book and on Ceramics.org say "I program... kiln fro 9999 degF to 1900degF so that I don't get an error message if the kiln can't cool at that rate" Is this a typo? Is the person meaning they program a "RATE of 9999 DEG/HR" (rather than entering 500 deg/hr?

If someone could help sort this out for me I would REALLY appreciate it. 

Take care,

Liane

[Min]

9999 means the kiln will drop in temperature as fast as it can without the elements coming on. It's a crash cool to the next temperature, in your case it would be from 2185 down to 1900. If you program in 500 degrees / hour and the kiln can't cool that fast you might get an error code. It's standard to enter 9999 when you want the kiln to free fall with no heat to the next segment.

Just as a side note, make sure you enter "0" hold after any of the segments if you don't want the kiln to hold at that temp.

Welcome to the forum!

[neilestrick]

9999 means full speed. Going up that means the elements are full on. Going down that means they're totally off and the kiln is cooling at its natural speed (crash cooling), which is pretty fast at first, then slower as it gets cooler. If you program a cooling rate of 500/hr it may not be able to cool that quickly once it drops a couple hundred degrees, and it'll give an error code. You can crash cool (9999) to 1900, or use a slow enough rate that the kiln can handle it, like 200/hr or slower. You'll need to decide if you need to cool from the peak temp, or let it crash and then do a controlled cooling through the period that it really makes a difference. In general, you won't see much in the way of changes in your glazes from slow cooling between the peak and 1900, so people often let it crash cool through that section, then do a controlled cooling from 1900 down to 1450ish. Below 1450 there are no benefits (to glazes) to a controlled cooling. I do a controlled cooling from the peak temp down to 1450 at 175/hr, because I have 3 kilns of radically different size, and they all crash at very different rates and I see  difference from kiln to kiln. By cooling from the peak they all cool at exactly the same rate for the entire process. Because I cool slowly from the peak, I do see more melt in my glazes than if I let it crash, because they're spending a little more time in the molten stage. If you want to avoid that, you can lower the peak temp a little to compensate.