Bisque firing issues still

[Gonepotty]

Hi all, wondering if anyone can help please. Bisque firing seems to not get to temp according to witness cones.

Firing to 990/1000 celcius. Cone packs 07, 06, 05. 

Cone 07 only very minuscule bend- I mean hardly noticeable. 

Top peep left out until 600 celcius and then bunged in.

No issues with glaze firing, reaching target temps perfectly and cones spot on. 

This is very frustrating as I think the bisque must have undefined due to glazed pots with new pinhole issues...

Thanks for any tips/help 

[Babs]

Could add a soak at end of schedule, say 20 mins and watch your cones through peep hole. Or set end temp to1020 and watch as above for cones to touch toes.

May be your thermocouple is on way out or needs an offset. Depends on controller type how you go about this.

[neilestrick]

What was the rate of climb for the final 100 degrees?

[Gonepotty]

It's a new kiln and only done 13 firings. (Skutt with touch screen controller).

Program is in celcius

Set 1 :80 degrees to 600

Set2: 100 degrees to 800

Set 3: 50 degrees to 1000 with 20min hold

[neilestrick]

5 hours ago, Gonepotty said:

It's a new kiln and only done 13 firings. (Skutt with touch screen controller).

Program is in celcius

Set 1 :80 degrees to 600

Set2: 100 degrees to 800

Set 3: 50 degrees to 1000 with 20min hold

That should have gotten you to cone 06, maybe even cone 05. It's really more important that it's firing accurately at glaze temps, which it is, so I wouldn't make any changes to the thermocouple offsets. I would just adjust the final temp up 30-40 degrees.

[Bill Kielb]

21 hours ago, Gonepotty said:

It's a new kiln and only done 13 firings. (Skutt with touch screen controller).

Program is in celcius

Set 1 :80 degrees to 600

Set2: 100 degrees to 800

Set 3: 50 degrees to 1000 with 20min hold

Just curious, since it is a Skutt with the touchscreen controller, why not use the cone fire programs rather than working with holds and various rates? Also  - to get a particular Orton cone to fall it’s customary to set the last segment rate to that shown in the chart. Begin that rate 100c before the cone temp. If you follow Orton, just curious if anyone has explained how that chart is intended to work?

[Kelly in AK]

It’s a legitimate question. I have programmed every segment of both bisque and glaze firings so I could have a sense I knew what the kiln was doing and evaluate the pots based on that. It didn’t last long. I can see the schedules in the manual, I’ve got no reason to believe I can make the kiln work better than the people who designed it. I did give it a good, honest try. 

Fewer button presses. Less to keep track of. Cone fire. 04. Speed (depends on how much of a hurry I’m in). Hold, if I’ve got some dodgy, gassy clay. Preheat is the revolutionary setting that took way too long for someone to come up with, no more explosions. Finally. That was the only real reason I used ramp/hold in the first place. 

That said…it seems like your schedule ought to have gotten you there, so please pardon my smarty pants opinion. You’re using cones, you will definitely know what your kiln is doing. 

I can be a simpleton. Celsius still eludes my grasp (not so much targets as rates, anymore). Try the cone fire mode though, if you haven’t. 

[Gonepotty]

10 hours ago, Bill Kielb said:

Just curious, since it is a Skutt with the touchscreen controller, why not use the cone fire programs rather than working with holds and various rates? Also  - to get a particular Orton cone to fall it’s customary to set the last segment rate to that shown in the chart. Begin that rate 100c before the cone temp. If you follow Orton, just curious if anyone has explained how that chart is intended to work?

I have tried using the pre programmed bisque firing and had similar issues with cones not bending. 

[Gonepotty]

7 hours ago, Kelly in AK said:

It’s a legitimate question. I have programmed every segment of both bisque and glaze firings so I could have a sense I knew what the kiln was doing and evaluate the pots based on that. It didn’t last long. I can see the schedules in the manual, I’ve got no reason to believe I can make the kiln work better than the people who designed it. I did give it a good, honest try. 

Fewer button presses. Less to keep track of. Cone fire. 04. Speed (depends on how much of a hurry I’m in). Hold, if I’ve got some dodgy, gassy clay. Preheat is the revolutionary setting that took way too long for someone to come up with, no more explosions. Finally. That was the only real reason I used ramp/hold in the first place. 

That said…it seems like your schedule ought to have gotten you there, so please pardon my smarty pants opinion. You’re using cones, you will definitely know what your kiln is doing. 

I can be a simpleton. Celsius still eludes my grasp (not so much targets as rates, anymore). Try the cone fire mode though, i

Thanks

[Bill Kielb]

7 hours ago, Gonepotty said:

I have tried using the pre programmed bisque firing and had similar issues with cones not bending. 

Hmm, the machine should generally ought to do it better or at least more consistently than creating a custom program. So when you create your schedules do you follow the last 100c requirements in the Orton chart?

[Min]

I think we are overcomplicating this.

If glaze is fine then don't mess with the TC offset. If bisque is under-firing then either fire to one cone hotter if using the preprogrammed schedule or increase the final temp like Neil said. Given that ^07 is barely bending and you are aiming for ^06 then try firing to preprogrammed ^05. Approx 30C between 07 and 06 and 06 and 05.