Skutt Slow Firing Program - Suggestions for values

[nathanhinshaw]

Hello all, I have a Skutt KM1027-3 which still has the optional "slow" cooling parameter that can be appended to the firing schedule.

When activate this function will take 3 parameters: Rate, Temp, and Hold. I am wondering if anyone here can give me any advice or suggestions for what those three values should be? This will be my first time using this function in this kiln so any guidance would be appreciated.

I am doing a ^6 fire and am interested in exploring the effect of a slower cool on the glazes.

Thanks in advance.

Edited February 4, 2023 by nathanhinshaw
Adding tags

[Pres]

Moving this to  Equipment.

best,

Pres

[Min]

There isn't a one size fits all type program for slow cooling. What works for one glaze won't necessarily give you the same results with another glazes. If the glaze is a high gloss one then slow cooling might not have any appreciable effect on it. If on the other hand it's one with fairly high amounts of one of the matting oxides (calcium, magnesium, alumina, strontium, barium, titanium or zinc) then slow cooling will more than likely have an effect. Getting the schedule is a bit of trial and error but a general starting place for a cone 6 glaze fire once it's reached it's top temperature could be 9999F to 1900F then ramping down at 150F an hour to 1400F then off.  (9999F is basically putting the kiln in a freefall without getting an error message)

If you do a drop and hold schedule for healing pinholes and blisters then I would suggest dropping your peak temperature at a rate of 9999F to 100F below your top temperature then holding there for approx 20 minutes then proceed with the 9999F to 1900F then 150F down to 1400F then off. 

If you find the glazes are too matte then increase the temperature it drops at (perhaps to 175F an hour) and/or raise the 1400F up and see how they turn out. If they are too glossy but might be matte with a slower cool (perhaps 125F and hour).

 

[PeterH]

Just eye candy:  glazes where slow cooling can have a dramatic effect.

From Super Cool! Slow Cooling in an Electric Kiln
https://ceramicartsnetwork.org/daily/article/Super-Cool-Slow-Cooling-in-an-Electric-Kiln

...and

[nathanhinshaw]

Thanks for the comment Min. I'm familiar with segments you mentioned, and understand there's no "one size fits all" for a slow cooling routine; so to try and bound the context of my question I'm limiting myself to the Skutt "cool" function which only allows for a single segment.

So my question really has two parts:

1.  Is there a good single segment cooling function?
2. What does that look like in practice when entering it on the controller?

The goal here is really just a test run and to dip my toes before writing custom firing / cooling segments. I've spent the majority of my years firing wood kilns so wrapping my head around surface effects in an electric kiln is the path I'm on.

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And thanks for the eye candy Peter, I'd been looking at that article and it was definitely a motivator to test out slower cooling!