kiln schedule

[electramom]

I have just gotten an old skutt 181 and am wondering how to determine the firing schedule. I am running seattle pottery ckk6 mostly all my clay is a cone 4-6 though my instructor said that the clay sometimes sticks to itself at 6. I need to do a bisque to cone 04 and a glaze firing at cone 6 glaze.  please help i want to have as good an outcome as I can. 

thank you

[Hulk]

Things that may help:

Kiln glasses - to protect your eyes from harmful rays and any flying bits - so you can watch witness cones through the peep hole(s). Cones tell the story!

Pyrometer - once you've dialed in your schedule(s), you may just watch the pyrometer, then check your witness cones afterward.

Powered kiln vent - moving a tiny stream of air through the kiln a) provides oxygen, b) helps keep the amount of yucky fumes down, and c) helps your kiln last

Testing! It might take a few runs to get dialed in - each clay (and glaze) may present a different challenge.

Notebook - take notes! It can be hard to remember what worked after a few years...
 

My first kiln was fully manual - three high/medium/low switches and a "kiln sitter" (which had a timer and a drop switch that would actuate when the small cone, or bar, melts).

For bisque firing, I'd run the kiln up to about 200F the night before - thinking that by the next morning, all would be very dry.
From there, I ran on high up to my target (1950F), with a half hour hold at 1500F.

For glaze firing, I'd run up to target temp (cone 5) on high, drop 100F, hold there for half hour, then set all on low for a slow cool to 1850F afore turning everything off, including the kiln fan.
 

I'm holding at 1500F for the bisque fire on account of I'd found the red clay (and to a lesser extent, brown and buff clays) behaves better when it gets a longer cook. My guess it's the larger off-gassing bits that get burned out better with more time.

I'm dropping and holding, then slow cooling for the glaze fire because it seems to help with "healing over" glaze defects.
 

Hope that helps!
A fully manual kiln requires some attention. That said, perhaps your kiln has a controller? lol!
Any road, be safe.

[Kelly in AK]

More information to digest:

Hulk’s post covered the territory I would think of first. He mentioned cones, I’ll reiterate that. You definitely want some free standing cones to record what actually happens. Especially since you haven’t used this kiln before. If problems come up (they will, this is ceramics) cones are invaluable for troubleshooting. The little cone in the sitter is there to shut the kiln off, but it has limited value for giving you information.

Make sure the shelves have some kiln wash on them, it sounds like your clay might “pluck” at the top of its range. That’s when bits fuse to the shelf, leaving pits on the foot of pots. If it’s plucking it’s probably close to warping, so leave room between pots in the glaze fire, say 1/2.”

The most critical stage at bisque is getting the pots dry, so that preheat part is important. A way I did it in the old days was to prop the lid an inch or so and turn the bottom switch on low for a few hours. Not so energy efficient, but it required less attentiveness.

Having your own kiln is awesome. Congratulations and good luck! 

[Sylla]

Hulk - how are you determining the temps on the manual kiln? Thanks!

 

[PeterH]

This may be your manual  https://skutt.com/images/KilnSitterManualOldPre1980.pdf

Note the section on Testing Models 181 & 145 on p2.

[Hulk]

I was using a pyrometer* from the start.

Early on, I was setting cone packs in front of the peep holes. I'd look at the cone packs as the kiln reached target temperature. Painted lines of iron oxide wash on the cones helped; the cones can be difficult to see when everything is orange/yellow hot!

Be absolutely sure to acquire the proper kiln glasses to protect against damaging rays and any flying bits.

As experience grew, I became more dependent on my notes and the pyrometer readings, and less dependent on watching cone packs during firing.
I'm still placing cone packs on each shelf, however, I look at them afterward.

The potter I bought the manual kiln from fired their cone 5/6 clay to a "soft" cone 7, so, I did the same, which was way too much heat work for the red clay I was using.
Now I'm using clays that mature at cone 5, so that's what I shoot for, a solid cone 5, which typically meant the middle shelves bend the 6 cone a bit.

I believe you can expect the sitter cone to bend before the witness cone(s) of the same number do.
For what it's worth, I was setting the sitter timer and the drop switch up just in case something dreadfully distracting occurred whist firing; I never depended on the sitter, instead, was watching the pyrometer, the time, and the cones.

I've learned a lot the hard way, and everything noted above, I'd read about in this Forum!
...even so, I still "had to" make my own mistakes.

Next up, brand new numerically controlled modern kiln with "zone control"!
...very much planning set up and watch cones through the peeps, starting out, for the kiln's pyrometers may be a bit off.

*Dual Input Pyrometer - Kilns | Ceramic Pottery Kiln, Glass Kiln, Pottery Wheels | Skutt

Edited June 10, 2023 by Hulk
watch cone packs, per others' experiences!

[electramom]

On 6/10/2023 at 6:02 AM, Sylla said:

Hulk - how are you determining the temps on the manual kiln? Thanks!

 

I havent run it yet. Im waiting on 04 cones and the sitters metal prongs had to be replaced so those just came yesterday. I will be running cones, but also using a pyrometer. I bought one before I got this kiln, I am also building (or amassing all of the parts) for a gas kiln,