How to Season a New Kiln Before First Firing (2026)
Seasoning a new kiln means running it through a controlled empty firing that cures the elements, burns off manufacturing residue, and proves the electrical setup before you load a single piece. Skip it and you risk cracked elements, off-gassing trapped in your first batch of ware, or a controller that fails mid-firing.
TL;DR
- Season a new kiln with one empty firing to cone 08 (1700°F) before loading ware or glass.
- Prop the lid or peep holes for the first hour to vent binder fumes on any 2026 model kiln.
- Check element continuity and controller calibration during the seasoning firing, not after.
- Olympic 139FLE and Jen-Ken AF3C kilns both need this step regardless of ceramic or glass use.
Seasoning firing at a glance
1700°F
Target temp, cone 08
empty seasoning firing
240V
Standard electric kiln circuit
12-18 in
Clearance from combustibles
Why this matters
A new kiln arrives with manufacturing oils on the elements, moisture in the insulating brick or fiber, and binder residue in any ceramic fiber components. None of that is dangerous long-term, but firing it directly with ware inside means those fumes and moisture end up in your kiln chamber during your first real load. Browse ProKilnSupply's kiln catalog and you'll notice every manufacturer's install guide — Olympic, Evenheat, Jen-Ken, Aim — calls for a break-in firing before first production use.
The seasoning firing also functions as a diagnostic. You find a bad element connection, a miswired thermocouple, or a controller calibration problem on an empty load instead of on a kiln full of greenware or fused glass. In 2026, most new electric kilns ship with digital controllers that log this first firing automatically, so treat it as both prep and inspection.
What you'll need
- The kiln itself, fully assembled and wired to a dedicated 240V circuit sized to the manufacturer's amperage spec
- 12 to 18 inches of clearance from walls and combustibles on all sides
- A pyrometric witness cone (cone 08 is standard for seasoning) if your controller doesn't have verified calibration
- Kiln furniture — shelves and posts — left OUT of the chamber for this firing; a heat treating furniture kit only goes in after seasoning is done
- Ventilation — an open window, exhaust fan, or downdraft vent system
- 30 to 90 minutes of supervised time, plus 3-4 hours of unattended firing and cooling
- A notebook or the controller's firing log to record ramp, hold, and any error codes
The steps
1. Confirm the electrical setup before you power on
Check that the kiln is on its own dedicated circuit at the correct voltage — 240V for most studio and school kilns — and that the breaker matches the amperage on the kiln's data plate. Undersized wiring is the single most common cause of a kiln that trips breakers or underfires during seasoning. Verify clearances (12-18 inches from walls, more for wood surfaces) before the first power-up, not after you smell something.
Common mistake: running an extension cord or a shared circuit to save an electrician visit. This causes voltage drop that shows up later as slow ramps and cone 08 that never quite hits temperature.
2. Leave the kiln empty for this firing
Do not load ware, glass, or shelves into the chamber. The seasoning firing exists specifically to burn off residue and cure the elements without contaminating a batch of work. Any furniture kit or shelf set goes in on the next firing, once seasoning is confirmed complete.
3. Prop the lid or crack the peep holes for the first hour
Manufacturing oils, binder in ceramic fiber lids, and ambient moisture in brick all off-gas in the first 200-400°F of the climb. Prop the lid an inch or leave peep hole plugs out for roughly the first hour of the firing so fumes vent instead of recirculating. Close everything up once you're past 400°F and the visible haze clears.
Common mistake: sealing the kiln tight from minute one. That traps moisture against the elements and brick, which is exactly what seasoning is meant to prevent.
4. Ramp slowly to cone 08 (roughly 1700°F)
Set the controller to a slow ramp — many manufacturers recommend 100-150°F per hour for a break-in firing — up to cone 08, around 1700°F, then hold 15-20 minutes. This is slower than a normal bisque or glass firing schedule on purpose; the slow climb gives brick and fiber time to dry out evenly instead of thermal-shocking.
5. Watch the elements during the climb
Electric kilns should show even, consistent glow across all elements once you're above roughly 1000°F. Patchy glow, one element dark while others fire, or visible sparking means a connection issue — shut the kiln down and call support before continuing. This is the cheapest point in the kiln's life to catch a bad element.
6. Verify the controller against a witness cone
Place a cone 08 witness cone visible through the peep hole, or check your controller's cone-fire log against the actual bend of the cone after cooling. A controller reading cone 08 while the cone shows more like cone 06 means recalibration before you trust it with real work. An Olympic Kiln 139FLE and most current-generation controllers store this reading automatically — pull the log rather than guessing.
7. Cool naturally and inspect before the next load
Let the kiln cool with the lid or door closed, no forced cooling. Once it's below 200°F, open it up and check the elements are still seated in their grooves, the shelves you'll use next have no visible warping in the chamber, and no cracks appeared in brick or fiber during the thermal cycle. Log the firing date, top temp, and any observations — this record matters for warranty claims if an element fails early.
Common mistake: loading the next firing immediately without letting the kiln cool and get inspected. A five-minute check now saves a mid-firing surprise later.
Glass kilns need the same step
Glass fusing and slumping kilns — a Jen-Ken AF3C glass kiln included — go through the identical seasoning logic even though the top temp for actual glass work runs lower than ceramic bisque. Season to cone 08 empty first, then run your actual fusing or slumping schedule on the next firing. Skipping seasoning on a glass kiln shows up as uneven element output that produces cold spots in your fused pieces.
Gear for a clean seasoning firing
Recommended sensor for calibrating controller readings against a witness cone.
$605
Protects shelves once you move to your first loaded firing after seasoning.
$9
Cuts power the moment the lid opens — a safety check worth adding before your first real firing.
$105
Troubleshooting
Strong smell and haze for hours, not just the first hour. Normal on a first firing but ventilate harder — open more windows or add a fan. If it persists past a second empty firing, call support; it may point to excess residue on a specific element batch.
Kiln won't climb past a certain temperature. Check the breaker size and voltage at the outlet first. A kiln rated for 240V running on a weak or shared circuit stalls out well below its rated max.
One element glows dimmer than the rest. Power down and check the element connection at the terminal block. A loose lead or a partially seated element causes uneven heating that gets worse with each firing, not better.
Controller throws an error code during seasoning. Note the exact code and firing stage before resetting. Most manufacturer error codes point to a specific sensor or relay fault that's far easier to diagnose while the kiln is still empty.
Witness cone shows a different temperature than the controller display. Recalibrate the controller against the cone reading before trusting cone-fire mode for real work — a swap to a Type S Thermocouple resolves persistent drift on older sensor styles.
Lid or door hisses or won't seal fully after cooling. Check the gasket seating; fiber gaskets settle after the first thermal cycle and sometimes need a quarter-turn adjustment on the latch.
Tools and resources
- Manufacturer install and firing guide that shipped with your specific kiln model
- A cone 08 witness cone for controller verification
- Kiln furniture kit for the load after seasoning — don't put it in during the seasoning firing itself
- Phone or text support from a kiln-only retailer if elements glow unevenly or the controller throws codes mid-firing
- A firing log, digital or paper, for warranty and maintenance records going forward into 2026 and beyond
What to do next
Once seasoning is done and the elements check out even, move on to your first loaded firing with furniture installed. If you're still deciding on kiln size for a home studio, the small kiln buying guide covers chamber size against typical batch volume before you commit to a second unit.
FAQ
How long does it take to season a new kiln?
A seasoning firing to cone 08 (about 1700°F) takes 3 to 5 hours including a slow ramp and natural cooling. Most electric kilns finish the full cycle, including cooldown below 200°F, within 6 to 8 hours total in 2026.
Do I need to season a kiln before every firing?
No, seasoning is a one-time step before the first firing of a new kiln. After that, you fire normally with ware or glass loaded, and only re-run an empty firing after major repairs like element replacement.
Can I skip seasoning if I'm in a hurry?
Skipping seasoning risks off-gassing binder fumes and moisture into your first real load, plus you lose the chance to catch a bad element or wiring fault on an empty firing. It costs one extra firing cycle to avoid a much costlier failure later.
What temperature should a seasoning firing reach?
Most manufacturers recommend cone 08, roughly 1700°F, for a break-in or seasoning firing on both ceramic and glass electric kilns. Check your specific model's install guide since some Aim and Evenheat heat-treating units specify a different target.
Is seasoning different for glass kilns versus pottery kilns?
The seasoning process is the same empty firing to cone 08 for both, even though actual glass fusing and slumping schedules run at lower peak temperatures than ceramic bisque. The Jen-Ken AF3C and similar glass kilns still need one full empty cycle before their first loaded firing.
Why does my new kiln smell during the first firing?
The smell comes from manufacturing oils on the elements and binder residue in insulating brick or fiber burning off, which is expected on any new kiln. Propping the lid or peep holes for the first hour and ventilating the room clears it faster.
What happens if I don't level or clear the kiln properly before seasoning?
Insufficient clearance from combustibles (under 12 inches) is a fire risk, and an unlevel kiln can cause uneven element wear over repeated firings. Confirm both before the first power-up, not during the seasoning firing itself.
Should I use a witness cone if my kiln has a digital controller?
Yes, for the first seasoning firing a witness cone confirms the controller's temperature reading matches actual heat work inside the chamber. Digital controllers can read accurately on the display while still being miscalibrated relative to the physical kiln.
One last thing
The seasoning firing is also the cheapest diagnostic you'll ever run on a kiln — an empty chamber costs nothing if an element fails, while the same fault discovered mid-bisque or mid-fuse can cost you the load. Run it before you touch a single piece of ware or glass, log the results, and you'll know exactly what your kiln does before it's doing it with something you can't replace.