Every van in this trade carries a heated caustic tank, and the tank is the reason a professional clean beats a Saturday afternoon with a scourer. It is also the reason a fair number of barbecues come back from a clean worse than they went in.
The dip works on a narrow set of materials: enamelled steel, stainless, chrome, the sort of thing an oven is made of. Barbecues are made of other things. Fired ceramic, seasoned cast iron, cast aluminium, felt, glass-fibre weave, vitreous enamel over a steel seam that is one chip away from rusting through.
Most of what follows is a list of what I take off the machine and leave on the driveway, and why. The list has got longer over the years, not shorter.
What happens when a caustic tank meets a ceramic kamado?
The short version is that the ceramic drinks it and gives it back to you six months later in a rack of ribs.
A kamado body – Big Green Egg, Kamado Joe, the various supermarket copies that turn up in gardens across Chiswick every May – is fired ceramic with a glaze on the outer shell and, on most models, a bare or lightly coated interior. That interior is porous at a scale you can’t see. It holds moisture, it holds smoke compounds, and it will hold sodium hydroxide solution for as long as it takes to migrate back out, which is a while. Rinsing does not resolve this. You cannot rinse the inside of a sponge you’ve soaked in bleach and call it neutral.
Not in my van, then. Ever, on any ceramic component: the body, the fire bowl, the fire ring, the ceramic heat deflector, the pizza stone if there is one.
The manufacturers say the same thing, and unusually for appliance manuals, they’re right and they say it plainly. Big Green Egg’s own guidance is that the thing cleans itself: run it up to 260 to 320 degrees with the vents open for half an hour or so, let the deposits carbonise, and brush the grid down when it’s cooled. That works because a kamado is a sealed ceramic vessel that holds heat brilliantly and because everything inside it is either ceramic or stainless.
Gaskets, bands and the price of a Nomex strip
The burn-off advice causes trouble at one specific point, and I spend a fair amount of time repairing damage done by owners who followed the instructions correctly.
The lid gasket on an older Egg is felt. On newer ones and on most Kamado Joes it’s a Nomex or fibreglass weave rated considerably higher. Felt gaskets are rated to somewhere around 260 degrees, and a cleaning burn that overshoots to 350 – which happens easily, because a kamado with the vents fully open and a bed of lump charcoal in it will run away from you – takes the felt off in strips. It welds to the ceramic. Then you’re scraping adhesive residue off a sealing face with a plastic blade and a solvent that has to be safe to cook over afterwards, and fitting a replacement strip that costs thirty-odd quid for the Egg and rather more for the Joe’s two-piece.
The metal band around the middle is the other casualty. Repeated hot cycling loosens the tension bolts, the hinge geometry shifts, and the lid stops meeting the base square. A gap of two millimetres at the front turns your temperature control into guesswork.
Both of those are ten-minute jobs if you know they’re coming and a weekend’s misery if you don’t.
Should cast iron grates ever go in the dip?
This is the argument I have most often with other cleaners, and I’ll take the unpopular side of it.
Caustic strips seasoning. That’s the entire point of caustic – it saponifies fat, and polymerised oil is fat that’s been heat-cured onto iron. Twenty minutes in a hot tank and a cast iron grate comes out grey, bare and chemically clean, which is exactly what you don’t want. Bare cast iron in a London garden will show orange flash rust before it’s dry. I’ve watched it happen on a driveway in Surbiton on a warm afternoon: out of the tank, rinsed, propped against the fence, and by the time I’d finished the lid there was a bloom across the whole grid.
So the trade answer is: dip it, then re-season immediately. Oil it, put it in a hot oven or back on the grill at 200-plus for an hour, repeat twice.
The problem is that nobody does the repeat twice. A single coat of thin oil polymerised once gives you a film. Seasoning is layers. The film comes off in the first cook. What the customer gets back is a grate that looks smart in the van and rusts by August.
Seasoning, flash rust and the twenty minutes after
My position: leave a well-seasoned cast iron grate alone. Scrape it hot, wipe it with an oiled cloth, and accept that the black patina is a working surface rather than dirt. It’s meant to look like that.
Where it earns a strip is when the seasoning has gone wrong – flaking in sheets, sticky and tacky rather than hard, or contaminated with carbonised sugar from a year of barbecue sauce. Flaking seasoning ends up in the food. That grate goes in the tank, comes out bare, and gets four passes of flaxseed or grapeseed before it leaves, which takes most of a day and is priced accordingly.
Porcelain-enamelled cast iron – Weber’s cooking grids, most of the Genesis and Spirit range – is a different object with the same name. The enamel is glass. Caustic will dull it and any impact will chip it, and a chipped enamel grid rusts from underneath and can’t be repaired.
Not in my van.
Which metals does caustic quietly destroy?
Aluminium, first and most dramatically.
Sodium hydroxide dissolves aluminium and produces hydrogen gas doing it. Drop a cast aluminium end cap or a Weber ash catcher into a heated caustic bath and you get a vigorous fizz, a black sludge, and a component that has visibly lost material. I’ve seen a hobbyist do this in a bucket with oven cleaner and a Genesis firebox and end up with pitting you could feel with a thumbnail. It isn’t a slow degradation. It’s minutes.
Which matters because a great deal of gas barbecue hardware is cast aluminium: cookboxes, end caps, burner mounting brackets, ash pans, some lid castings on older kit.
Anodised aluminium is worse in the cosmetic sense. The anodised layer goes patchy black and there is no recovering it.
Aluminium castings, ash pans and the hydrogen problem
Stainless is generally fine, with a caveat. Burner tubes are stainless on most decent grills and survive a dip, but the venturi ends and the ignition electrodes don’t want soaking, and a burner that comes back with tank residue in the ports will burn yellow and sooty until it’s cleared. I take burners out and do them dry – brush through the ports with a drill bit of the right gauge, vacuum the tube, check the crossover.
Vitreous enamel lids, the Weber kettle sort, sit somewhere in between. The enamel itself tolerates a short alkaline contact. What doesn’t tolerate it is the seam where the enamel meets bare steel at the vent cutouts and the handle mounts, and any existing chip becomes a rust site with the coating undermined around it. So a kettle lid gets washed by hand, warm, with a degreaser and a nylon pad, and it takes fifteen minutes and looks better than a dipped one.
Thermometer stems, plastic control knobs, rubber wheels, wooden handles, felt, the electronics on a pellet grill’s controller and auger housing. Obvious, all of it, and I’ve still collected two Traeger control boards ruined by somebody’s pressure washer.
Pellet grills deserve a line of their own. The barrel builds a creosote layer that behaves like the deposit in a charcoal flue, the firepot fills with fused ash clinker, and the auger tube holds damp pellets that swell and jam. None of it responds to chemicals and all of it responds to a scraper, a shop vac and forty minutes. The controller and the induction fan stay dry. Not in my van, that housing – it comes off the machine and goes nowhere near water.
What does a barbecue clean look like when nothing goes in the tank?
Slower, mostly. And more of it done on site.
The stainless and enamel steel components – flavorizer bars, grease trays, warming racks, the drip pan, the burner covers – go in the tank and come back transformed, because that’s what the tank is for. Everything else gets hand work. Firebox scraped dry, cookbox vacuumed, the grease channel cleared with a plastic scraper rather than steel, hood interior taken back with a non-caustic gel that doesn’t sit on the enamel.
On a kamado I mostly do the things the owner can’t: strip and replace the gasket, re-tension the band, true the hinge, take the internal ceramics out and inspect the fire ring for the hairline cracks that turn into a split fire bowl.
I did a Kamado Joe in Blackheath last summer where the owner had been cleaning the inside with washing-up liquid for two years. Everything he cooked tasted faintly of soap and he’d blamed the charcoal, then the local butcher.
Wire brushes, bristles and the tool I won’t use
Wire brushes should not exist. That’s my strongest opinion in this trade and I’ll hold it against the entire retail sector, which sells them by the thousand every spring.
Loose bristles come off cheap brushes, sit on the grate, transfer to food and get swallowed. There is a documented pattern of A&E presentations from exactly this – throat and bowel perforations, imaging, surgery – and the injuries are rare enough that people dismiss the risk and severe enough that they shouldn’t. A coiled stainless scraper, a wooden paddle scraper, a pumice block for enamel, half an onion on a fork if you’re feeling traditional. All of them work.
The gas grill in a garden in Muswell Hill I service twice a year has never met a brush and its grids are in better shape than kit half their age.
Now the part that loses me money. If you own a kamado and nothing else, you probably don’t need a cleaner. Run it hot for half an hour twice a season with a fresh gasket in place, brush the grid, empty the ash, keep the ceramics dry over winter under a proper cover. Call me when the gasket goes or the band slips.
The Weber cabinet with four years of grease in the cookbox is a different conversation.
