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Clean a pizza oven with heat, not chemicals. Run it at full temperature for 20 to 30 minutes at the end of a session and the spilled cheese and dropped toppings carbonize to ash. Let it cool completely, brush the ash off the stone with a dry metal brush, and remove wood ash into a lidded metal container outdoors. Never use soap, detergent or oven cleaner on a cooking stone — it is porous and it will transfer the taste to your food — and never put water on a hot stone, which is the most common cause of a cracked one.
How does the burn-off method work?
Cordierite stone and steel chambers both self-clean at pizza temperatures, which is convenient and means you almost never need to scrub anything.
- At the end of a cooking session, turn the oven up to full — or in a wood oven, add a couple of pieces and let it run hot.
- Hold it there for 20 to 30 minutes. Organic residue on the stone — cheese, sauce, oil, dropped basil — reaches its combustion point and turns to loose gray ash.
- Shut the oven down and let it cool completely. This is not optional and it is where people get impatient. A stone that goes from 900°F to a wet cloth cracks.
- Brush the cold stone dry with a brass or stainless brush, working the ash toward the mouth and out.
- Wipe the chamber and the door glass with a barely damp cloth if you want, avoiding the stone itself.
Ooni's own guidance on cleaning a pizza stone makes the same point — heat first, and let the stone cool in the oven before it is handled.
Is a stained stone dirty?
No, and the sooner you accept this the happier you will be. A pizza stone goes from pale gray to blotched brown to substantially black over its first season, and that is carbon and polymerized oil bonded into the surface. It is inert, it does not smell, it does not transfer to food, and it does not affect how the stone cooks. It is functionally the same thing as seasoning on cast iron.
What you are trying to remove is loose material — ash, crumbs, unburnt cheese, flour that would otherwise scorch and taste bitter on the next pizza. Anything bonded to the stone stays, and every attempt to scrub it out with soap or abrasive cleaner makes the stone worse rather than better.
One genuine exception: a thick, greasy, tacky black film that transfers to your finger is not seasoning, it is unburnt residue from a bad fire. Run the oven hot to burn it off, then fix the underlying cause — see the soot section below.
What should you never do to a pizza stone?
| Do not | Why not | Do this instead |
|---|---|---|
| Use soap or detergent | Porous stone absorbs it and transfers the taste to food | Burn it off at full heat |
| Use oven cleaner | Caustic chemicals soak in; food safety problem | Burn it off at full heat |
| Put water on a hot stone | Thermal shock — the classic cause of a cracked stone | Let it cool completely first |
| Soak it or put it in a dishwasher | Detergent plus deep saturation; cracks on next heating | Dry brush only |
| Scrape with a sharp metal edge | Gouges the surface and dough catches in the gouge | Brass or stainless brush, or a plastic scraper |
| Oil or season it like cast iron | It is not cast iron — oil goes rancid in the pores | Nothing; it seasons itself |
| Store the oven uncovered | Stone absorbs rain, then cracks on fast preheat | Fitted cover, sheltered storage over winter |
How do you deal with ash in a wood-fired oven?
Every session in a wood or charcoal oven leaves ash, and it needs to come out — not because it affects the next pizza much, but because of what it does to the oven.
Wet ash is mildly caustic and attacks steel from the inside. Ash left sitting in the chamber absorbs moisture from the air and from rain that finds its way in, and the resulting alkaline slurry corrodes the floor and the lower walls. Ovens stored dirty rust out considerably faster than ovens stored empty — this is the single biggest avoidable cause of a shortened oven life.
The routine:
- Wait until it is completely cold. Ash that looks dead holds live embers for a day or more, and every year fire departments attend fires started by ash bins emptied too early.
- Shovel or brush it out with a small ash shovel or a stiff brush, into a metal container with a lid. Never a plastic bucket, never a paper bag, never directly into a household trash can.
- Store that container outdoors, on a non-combustible surface, away from the house and anything that will burn, until you are confident it is fully cold — a day or two is sensible.
- Never bring warm ash indoors, into a garage, or onto a wooden deck.
- Cold hardwood ash can go on a compost pile or garden beds in modest amounts, since it is alkaline and adds potassium. Do not use ash from charcoal briquettes, treated wood or anything with additives.
General outdoor fire safety guidance is worth a read: NFPA's grilling safety page and the US Fire Administration's cooking fire prevention page both cover disposal of hot cooking residue.
What if the inside is thick with soot?
Light black carbon everywhere is normal. Thick, greasy soot that comes off on your hand — and a viewing window you can no longer see through — means the fire is burning badly, and the fix is upstream of cleaning.
- Wet or unseasoned wood. The most common cause by a distance. Wood above roughly twenty percent moisture spends its energy boiling off water instead of burning cleanly, and the result is smoke, soot and a floor that will not come up to temperature. Kiln-dried hardwood, split to finger-to-wrist thickness, fixes most soot problems on its own.
- Softwood. Pine and spruce resin creosotes the chamber and the chimney. Do not burn it for cooking.
- Not enough air. A damper closed too far, or a fire smothered under too much fuel, smolders rather than burns. Open the damper, feed less at a time, and let the flame establish.
- Chimney restriction. Soot and creosote build up in the flue over seasons and reduce draw, which makes the burn dirtier, which builds more soot. Check and brush the chimney a couple of times a season.
What to burn and what never to burn is covered in detail in our wood-fired pizza oven guide. Short version: kiln-dried hardwood only, and never treated, painted or engineered lumber, pallets or driftwood.
Cleaning a gas oven
Gas ovens are simpler because there is no ash and much less soot, but two things need attention.
The burner and its ports. Grease and debris block gas ports and produce an uneven or yellow flame instead of a clean blue one. With the propane disconnected and the oven cold, check the burner tube and clear the ports with a soft brush or a thin wire. A yellow, lazy or noisy flame is a signal to stop and look rather than to keep cooking.
The regulator and hose. Inspect the hose for cracks and abrasion at the start of each season, and check connections with soapy water — bubbles mean a leak. Never use a lighter to look for a gas leak. If you smell propane, shut the tank valve and move away before doing anything else.
Otherwise, burn off, cool, brush the stone, and wipe the exterior. Our gas grill cleaning guide covers burner and hose maintenance in more depth and the same principles apply.
What if the stone cracks?
It happens, and it is nearly always thermal shock rather than a defect. The three causes in order of frequency: water on a hot stone, a stone that absorbed rain over winter meeting a fast preheat, and a very cold stone taken to full temperature too quickly.
A hairline crack is usually cosmetic and the stone keeps working — plenty of professional ovens run cracked stones for years. A crack that has separated, lifted at an edge, or created a step that catches dough is worth replacing, and replacement stones are inexpensive and widely available for the major brands. Prevention is simple: keep the oven covered, let the stone heat and cool with the oven, and never put water on it warm.
Storing it between sessions
- Cover it year-round with a fitted cover. Water in the chamber is the enemy — it soaks the stone and corrodes the steel.
- Empty the ash first, cold. Never store a wood oven with ash in it.
- Disconnect and store the propane tank separately, upright, outdoors, never in a house or basement. Our guide on leaving a propane tank outside in winter covers this.
- Bring the oven under shelter over a northern winter if you can — a garage or shed, once it is completely cold and clean. Freeze-thaw cycles on a damp stone are what eventually splits it.
- Store the stone dry, and if the oven has been sitting damp, run it at moderate heat for 20 to 30 minutes before the first fast preheat of the season to drive the moisture out gently.
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