03DSFF - Cone 03 Fast Fire
04DSDH - Low Temperature Drop-and-Hold
BQ1000 - Plainsman Electric Bisque Firing Schedule

C10RPL - Plainsman Cone 10R Firing
C6DHSC - Plainsman Cone 6 Slow Cool (Reactive glazes)
C6MSGL1 - Mastering Glazes Cone 6
C6PLST - Plainsman Cone 6 Electric Standard
FSCG1 - Shimbo Crystal Schedule 1
FSCGB1 - Bory 1 Fara Shimbo Crystalline Glaze
FSCGCL - Celestite
FSCGWM - Wollast-O-Matte Fara Shimbo Crystalline Glaze
FSCRGL - GC106 Base for Crystalline Glazes
FSHP1 - Shimbo Crystal Holding Pattern 1
FSHP2 - Shimbo Crystal Holding Pattern 2
FSHP3 - Shimbo Crystal Holding Pattern 3
FSNM5 - Fa's Number Five
PLC6CR - Cone 6 Crystal Glaze Plainsman
PLC6DS - Cone 6 Drop-and-Soak Firing Schedule

C04PLTP Firing Schedule

Plainsman Typical Cone 04

In the Plainsman lab we have standardized on a simple firing curve for test specimens that provides a soak for final drying and then proceeds to 100 degrees below the final temperature at 400 degrees per hour, then slows to 100 degrees per hour for the final stage. The cool is freefall. Of course, depending on the kiln used, the rate-of-rise might be slower, especially in the later stages.

Step °C °F Hold Time
1 100°C/hr to 100C  180°F/hr to 212F  60min 2:02  
2 150°C/hr to 960C  270°F/hr to 1760F  0 7:46  
3 100°C/hr to 1060C  180°F/hr to 1940F  5min 8:51  
4 Freefall°C/hr to 30C  0°F/hr to 86F    8:51  
Start temperature assumed: 25°C or 75°F
100°F is 37°C, but 100 fahrenheit degrees is 55 celsius degrees, that is an important distinction to understand the above temperature conversions.

Related Information

Program your firings manually, calibrate the final temperature using cones

Here is an example of our lab firing schedule for cone 10 oxidation (which the cone-fire mode does not do correctly). To actually go to cone 10 we need to manually create a program that fires higher than the built in cone-fire one. Determining how high to go is a matter repeated firings verified using a self supporting cone (regular cones are not accurate). In our lab we keep notes in the schedule record in our account at insight-live.com. And we have a chart on the wall showing the latest temperature for each of the cones we fire to. What about cone 6? Controllers fire it to 2235, we put down a cone at 2200!

What position should the cone be for correct firing?

Two orton cones, one bent to 6 oclock, the other 4 oclock.

Four o'clock. These are self-supporting cones, use these. I was consistently getting the cone on the left using a custom-programmed firing schedule to 2204F (for cone 6 with ten minute hold). However Orton recommends that the tip of the self supporting cone should be even with the top of the base, not the bottom. So I adjusted the program to finish at 2200F and got the cone on the right. But note: This applies to that kiln with that pyrometer, our other test kiln puts cone 6 at 4 o'clock at 2195F. Of course, if you want the kiln to hold at cone 6 for longer the cone will bend further, so the top temperature would need to be reduced to compensate for that. If you are using the automatic programs (e.g. cone 6 schedules go to around 2230!) your kiln is almost certainly over firing.

Links

Recipes G2853B - Cone 04 Clear Ravenscrag School Glaze
A Ravenscrag Slip base made by simply mixing it 50:50 with a frit
Firing Schedules Plainsman Electric Bisque Firing Schedule
Three-step to 1832F
Typecodes Oxidation Firing

By Tony Hansen


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