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03DSFF - Cone 03 Fast Fire
04DSDH - Low Temperature Drop-and-Hold
BQ1000 - Plainsman Electric Bisque Firing Schedule
BTFB04 - Bartlett Fast Bisque Cone 04
BTSG05 - Bartlett Slow Glaze Cone 05
C04PLTP - Plainsman Typical Cone 04

C5DHSC - Plainsman Cone 5 Drop-and-Hold Slow-Cool
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

C10RPL Firing Schedule

Plainsman Cone 10R Firing

Every gas kiln is different so this schedule may not work for you if you kiln does not cool at the same rather or maintain the same atmosphere. Our kiln is brick construction, downdraft, four natural gas burners, about 30 cubic feet. It fires evenly top-to-bottom and front-to-back. We have had and used others but none of them equaled the quality of firing this can produce. It was built by Luke Lindoe.

It can rise while reducing so we do not do a separate body and glaze reduction (with an oxidation climb between). Reduction is consistent throughout the kiln, enough to produce a clear bluish flame at the peepholes (with some yellow at the damper). We soak for half an hour in oxidation at the end. To prevent temperature rise during this phase we turn the gas pressure to almost zero (allowing it to drop a little). On shutdown we seal it up but temperature still free falls (although slower than a fibre kiln would). We open it at about 200F two days later.

Step °C °F Hold Time
1 10°C/hr to 120C  18°F/hr to 248F  0 12:23 Heat up overnight on pilots
2 50°C/hr to 550C  90°F/hr to 1022F  0 20:59  
3 100°C/hr to 980C  180°F/hr to 1796F  0 25:17  
4 50°C/hr to 1300C  90°F/hr to 2372F  0 31:41 Start light reduction beginning of this step
5 0°C/hr to 1280C  0°F/hr to 2336F  30min 31:41 Oxidation this step
6 0°C/hr to 30C  0°F/hr to 86F    31:41  
Start temperature assumed: 25°C or 75°F
"Fahrenheit degrees" is not the same as "degrees Fahrenheit". A 100° reading on a Fahrenheit thermometer is equal to a 37° reading on a Celcius thermometer. But "100 Fahrenheit degrees of temperature change" is equivalent "55 Celsius degrees of change". That is an important distinction to understand the above temperature conversions.

Related Information

How many degrees between these cone positions?

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

I was consistently getting the cone on the left when 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 (they consider the indicating part of the cone to be the part above the base). So I adjusted the program to finish at 2200F and got the cone on the right. But note: This applies to that kiln at that point in time (with that pyrometer and that firing schedule). Our other test kiln bends the cone to 5 o'clock at 2195F. Since kiln controllers fire cone 6 at 2230 (for the built-in one-button firings) your kiln is almost certainly over firing!

Gas kiln near cone 10R in the Plainsman Clays studio

It is old, but nothing we have ever used fires as evenly and reliably as this downdraft kiln. It was built by Luke Lindoe in the 1960s. I have used it through my entire life as a potter since the early 1970s. Two burners at 2 inches oil-column will take it to 1000F fairly quickly, but it takes 4 burners at 4 inches and 20 hours to get it to cone 10. I can judge the back pressure and degree of reduction by the length and color of the flames at the peepholes and color of the flame passing the damper at the back. Changing the damper position by an eighth of an inch during reduction is enough to discern a change in the flame.

Cone 10R load of fired ware in Plainsman gas kiln

It fires evenly in temperature and atmosphere from top to bottom, front to back. Nothing more can be expected for any studio kiln. We use the C10RPL firing schedule.

Another view of the gas kiln in the Plainsman clay studio

Example of a modern automatic firing reduction gas kiln for use by studio potters

Courtesy of Bailey Kilns.


Recipes GR10-A - Pure Ravenscrag Slip
Ravenscrag all by itself makes a great cone 10 reduction semi-gloss glaze. It also has great working properties.
Recipes GA10-D - Alberta Slip Black Cone 10R
You can make a black glaze at cone 10R using only 1% black stain in a 100% calcine:raw mix of Alberta Slip
Recipes GR10-B - Ravenscrag Cone 10R Gloss Base
Cone 10 Reduction glaze made using 90% Ravenscrag Slip.
Recipes G1947U - Cone 10 Glossy Transparent Base Glaze
Reliable widely used base glaze for cone 10 porcelains and whitewares. The original recipe was developed from a glaze used for porcelain insulators.
Recipes G2571A - Cone 10 Silky Dolomite Matte Base Glaze
A cone 10R dolomite matte having a pleasant silky surface, it does not cutlery mark, stain or craze on common bodies
Recipes GA10-B - Alberta Slip Tenmoku Cone 10R
You can make a tenmoku from Alberta Slip by adding only 2% iron oxide and 5% calcium carbonate
Recipes L3341B - Alberta Slip Iron Crystal Cone 10R
By adding a little iron to 100% Alberta Slip you can make an iron crystal glaze.
Typecodes Reduction Firing
Firing Schedules Plainsman Electric Bisque Firing Schedule
Three-step to 1832F

By Tony Hansen

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