Pottery kiln firing schedule builder
Pick a cone, choose bisque or glaze, and set the speed for a print-ready ramp and hold schedule.
This schedule is guidance, not a guarantee. Kilns, clays, and glazes vary. Always check your kiln and clay or glaze maker instructions, fire a witness cone, and adjust if the cone reads under or over. A wrong schedule can crack ware or stress a kiln.
How the builder works
The builder turns three choices into a controller-ready program. The cone sets the heat-work target, bisque or glaze sets the segment shape, and the speed sets the ramp rates. The shape follows the factory Cone Fire programs in Bartlett, Skutt, and L&L controllers: a gentle start while moisture leaves, a steady climb, an eased stretch through quartz inversion, then a slow final approach.
The peak is read, not guessed. A cone measures heat-work, time and temperature together, so the builder takes each peak from the Orton self-supporting cone chart at the published heating rate closest to your final ramp: the 108 F per hour column for slow and medium firings, the 270 F per hour column for fast.
New to segments? Start with how kiln firing schedules work, or look up any cone on the Orton cone chart.
What do the ramp and hold numbers mean?
Each row of a schedule is one instruction: climb at the ramp rate, in degrees per hour, until the kiln reaches the target temperature, then wait there for the hold time. A controller runs the rows in order. So "rate 200, target 250, hold 0" means climb at 200 F per hour to 250 F and move straight on.
The final ramp does the most work. Over the last stretch it decides how much heat-work the ware receives: 80 F per hour on slow, 120 on medium, 200 on fast. A slower final ramp bends the same cone at a lower temperature, which is why each speed reads its peak from a matching Orton column.
A worked example: cone 6 glaze at medium speed
Ask for a cone 6 glaze firing at medium speed in Fahrenheit and the builder returns the five segments below. The final ramp is 120 F per hour, closest to the 108 column, so the peak is 2232 F (1222 C), with a 10 minute hold so the melt can level out.
| Step | Ramp (F/hr) | Target (F) | Hold | What it does |
|---|---|---|---|---|
| 1 | 200 | 250 | none | Short candle so leftover moisture leaves as steam. |
| 2 | 400 | 1000 | none | Steady climb through the early stage. |
| 3 | 180 | 1150 | none | Eases through quartz inversion near 1063 F. |
| 4 | 350 | 1982 | none | Approach to the glaze maturity range. |
| 5 | 120 | 2232 | 10 min | Slow final approach lands cone 6; the hold smooths the melt. |
From a 75 F start the ramps and the hold add up to 8 h 13 min. Cooling comes on top: a loaded kiln takes many more hours to fall below 200 F, and it should do that on its own with the lid closed.
Cone temperatures at a glance
These are the peaks the builder aims for at the standard 108 F per hour final rate, straight from the Orton chart. Bisque work usually stops at cone 08 to 04, most mid-range stoneware glazes mature at cone 6, and cone 9 to 10 is high fire for stoneware and porcelain.
| Cone | Peak (F) | Peak (C) | Typical use |
|---|---|---|---|
| 08 | 1728 F | 942 C | Bisque |
| 06 | 1828 F | 998 C | Bisque or low-fire glaze |
| 05 | 1888 F | 1031 C | Bisque or low-fire glaze |
| 04 | 1945 F | 1063 C | Bisque or low-fire glaze |
| 6 | 2232 F | 1222 C | Mid-range glaze |
| 9 | 2300 F | 1260 C | High fire |
| 10 | 2345 F | 1285 C | High fire |
The full Orton cone chart lists every cone from 022 to 10, in F and C, at both heating rates.
Limits and safety
The schedule is a solid starting point, not a promise. It assumes an electric kiln with a programmable controller, a start near 75 F, and an evenly packed load. It cannot know how your elements have aged, how far your thermocouple has drifted, or how a tight load slows the heat.
- Fire a witness cone every firing. If it reads under or over, adjust the final hold in 5 minute steps before changing any ramp.
- When your kiln, clay, or glaze maker instructions disagree with this tool, follow the maker. They know your materials; the builder only knows the published programs.
- Damp or thick-walled work needs a longer candle than the default. Hold near 200 F for 30 to 60 minutes, longer for very thick pieces.
- Vent the room while the kiln burns off organics, and let the kiln cool with the lid closed until it is below about 200 F.
Sources
- Edward Orton Jr. Ceramic Foundation, Temperature Equivalent Chart for Orton Pyrometric Cones (self-supporting). ortonceramic.com.
- Skutt, KilnMaster programming manual, Cone Fire mode. skutt.com.
- Ceramic Arts Network, Techno File: Kiln Firing Schedules. ceramicartsnetwork.org.
Frequently asked questions
Which cones can I build a schedule for?
For bisque, the common low-fire cones 08, 06, 05, and 04. For glaze, low-fire 06 through 04 and mid-to-high-fire cones 5, 6, 8, 9, and 10. These cover almost all studio earthenware, stoneware, and porcelain work. Every peak temperature is the Orton self-supporting cone equivalent.
What do slow, medium, and fast change?
They set the ramp rates, especially the final segment: about 80 F per hour for slow, 120 for medium, and 200 for fast over the last stretch. Slower firing gives more even heat and bends the cone at a slightly lower temperature; faster firing saves time but pushes the peak up. Bisque also uses slower early ramps than glaze.
Should I add a hold at the top?
Glaze schedules include a short hold by default to let the melt smooth out. For glossy glazes that pinhole, try the drop-and-hold option, which cools fast just below peak and soaks so bubbles burst and heal. Bisque firings usually need no top hold.
How long will the firing take?
The builder shows an estimated ramp time from room temperature to peak, plus holds. A slow bisque to cone 04 runs about 13 hours; a medium glaze to cone 6 runs roughly 8 hours. Cooling adds many more hours, and you should let the kiln cool on its own with the lid closed.