Two grills sit side by side in a showroom. Both are described as stainless steel. Both look identical under the lights. Three summers later one still looks like the day it arrived and the other has orange bloom creeping out of every weld and fastener. The spec sheet told you which was which — it was the three-digit number almost nobody reads.
Stainless steel is not one material. It is a family of alloys with meaningfully different behavior outdoors, and the difference between the two grades you will most often encounter on a grill comes down to a single element. This is what that number means, where each grade actually shows up on an outdoor appliance, and what to ask before you spend real money.
If you only read one section
Grade 304 contains nickel. Grade 430 essentially does not. That nickel changes the steel’s crystal structure and gives it considerably better resistance to the two things that attack outdoor cooking equipment hardest: chlorides and acids.
In practice, 430 is a reasonable material for a dry indoor environment or a low-exposure component. It is a poor choice for the exterior of an appliance that lives through rain, sprinkler overspray, pool chemistry, and coastal air. 304 is the grade specified across commercial kitchens and marine applications for exactly that reason.
What the numbers actually describe
All stainless steel works the same way: chromium in the alloy reacts with oxygen to form a thin, invisible, self-repairing oxide layer on the surface. That passive layer is what protects the iron underneath. Scratch it and it reforms. The question is how well it holds up when something attacks it.
Grade 304 — austenitic
Often called 18/8 for that ratio. The nickel content shifts the steel into an austenitic crystal structure, which is more ductile, generally non-magnetic in its annealed state, and markedly more resistant to chloride and acid attack.
Grade 430 — ferritic
Similar chromium, essentially no nickel. That keeps the structure ferritic and magnetic, and it costs meaningfully less to produce — nickel is the expensive ingredient. It also leaves the alloy considerably more vulnerable to pitting in salt and chlorine environments.
And the grade above both
Grade 316 adds roughly two percent molybdenum on top of the 304 recipe, which pushes chloride resistance higher again. It is the marine specification, and it costs accordingly. You will occasionally see it on fasteners or specific hardware rather than whole appliance bodies.
How the two behave outdoors
What failure actually looks like
People expect stainless to fail by rusting through. It rarely does. What happens instead is pitting — microscopic breaches in the passive layer where a chloride ion has punched through, which then propagate downward while the surrounding surface still looks fine. On a lower grade in a coastal or poolside setting, that shows up as fine orange speckling around welds, seams, screw heads, and any spot where the surface was worked or heated.
Once it starts, it does not reverse. That is why the grade decision is made at purchase rather than fixed later.
Components that hold standing water and ice — sinks, ice bins, drain pans — are where grade choice shows up fastest.
Where the grade quietly changes
Here is the thing to watch for, and it is entirely legal and entirely common: a grill can be advertised as stainless steel, and even as 304 stainless steel, while only some of it is 304.
An outdoor grill is not one piece of metal. It is a hood, a firebox, a control panel, burners, grates, flame tamers, a drip tray, fasteners, and on freestanding units a cart and doors. Those components can be specified independently. The visible hood is the part everyone touches in a showroom, so the visible hood is the part most likely to be the good stuff.
Questions worth asking before you buy
- Which grade is the hood and the exterior body?
- Which grade are the burners? They see the most thermal cycling of any component.
- Which grade are the cooking grates and the flame tamers?
- Which grade is the drip tray, which holds grease and moisture longer than anything else?
- On a freestanding unit, which grade is the cart and the door panels?
- Are the fasteners stainless, and to what grade?
The magnet trick, and its limits
Grade 430 is magnetic. Annealed 304 generally is not. So a fridge magnet held against a panel gives you a rough indication in about two seconds, which is genuinely useful when you are standing in front of an appliance with no documentation.
Two caveats keep it from being definitive. First, 304 that has been cold worked — stamped, bent, formed — can develop some magnetic response at the worked areas, so a slight pull near a formed edge does not prove anything. Second, a magnet tells you austenitic versus ferritic; it does not distinguish 304 from 316, and it does not tell you what the component underneath the panel is made from.
Treat it as a screening tool. If a panel grabs a magnet firmly and flat, that is worth a question. The documentation is the answer.
Most rust on stainless is not the stainless
This is the single most useful thing in this article, and it applies regardless of which grade you own.
When people see orange spots on a stainless grill, they conclude the metal failed. Frequently what actually happened is free iron contamination — particles of ordinary carbon steel deposited on the surface, which then rust in place. The stainless underneath is fine. The rust is sitting on top of it.
Where that iron comes from
Carbon steel grill brushes
The most common source by a distance. A brush with plain steel bristles leaves microscopic fragments embedded in the surface every time you scrub. Use a brush intended for stainless, or a non-metallic option.
Steel wool and abrasive pads
Steel wool is carbon steel. Using it on a stainless surface deposits iron and scratches through the passive layer at the same time, which is the worst of both outcomes.
Chlorine-based cleaners
Bleach and chloride-heavy cleaners attack the passive layer directly. Follow the manufacturer’s approved products rather than reaching for whatever is under the sink.
Nearby construction or landscaping
Grinding, cutting, or drilling steel anywhere near an open outdoor kitchen throws hot iron particles onto every surface in range. Cover appliances during work.
Where grade matters most
Coastal properties
Salt air carries chlorides continuously, not just during storms. Within a few miles of open water, grade is the difference between an appliance that ages and one that deteriorates.
Poolside installations
Chlorinated splash and the vapor above a pool deck are both aggressive. An outdoor kitchen built adjacent to a pool sees more chemical exposure than most people expect.
Irrigation overspray
Underestimated constantly. A sprinkler head that hits the island twice a day is a standing-water problem, and hard water leaves mineral deposits that hold moisture against the surface.
Freeze-thaw climates
Repeated thermal cycling combined with road salt tracked into the yard is its own stress case, particularly on welds and seams.
Covered outdoor kitchens
Lower direct exposure, but grease vapor and trapped humidity under a roof create their own environment. Ventilation and cleaning routine matter more here than grade alone.
Dry inland patios
The gentlest case, and the one where a lower grade survives longest. Even so, the cost difference over a decade of ownership is rarely what tips the decision.
Questions we get asked most
Is 304 stainless steel rust proof?
No, and be skeptical of anyone who says otherwise. It is corrosion resistant, which is a different claim. Under sustained chloride exposure, poor cleaning practice, or free iron contamination, 304 can and does show surface staining and pitting. It resists those conditions considerably better than 430 — that is the whole value of the grade.
Why do some grills use 430 at all?
Cost. Nickel is the expensive component in stainless steel, and removing it takes real money out of the bill of materials. On components with low exposure, that can be a defensible engineering choice. On the exterior of an appliance living outdoors year round, it is a choice you will notice.
Can I tell the grade by looking at it?
Not reliably. Finish, polish, and brightness are surface treatments, not indicators of alloy. A well-polished 430 panel looks better in a showroom than a brushed 304 one. Use the documentation, and the magnet as a rough screen.
My grill already has rust spots. Is it ruined?
Probably not. Surface rust from free iron contamination often cleans off with a product formulated for stainless and a non-metallic pad, worked with the grain. Genuine pitting — small craters you can feel — is structural and does not come out. Start with the assumption it is contamination, since that is more common, and follow the manufacturer’s care guidance.
Does grade affect how the grill cooks?
Not directly. What affects cooking is burner construction, heat distribution, grate mass, and hood design. Grade affects how long all of that stays in good condition. A dual-wall hood holds heat better than a single-wall one regardless of alloy; a heavier grate puts better marks on a steak regardless of alloy.
Should I pay for 316 instead?
For most residential installations, 304 is the practical specification and 316 is more than the situation calls for. Directly on the water, in a hard marine environment, the conversation changes — and it is worth having with your builder rather than resolving from a web page.
What grade does KoKoMo use?
KoKoMo specifies 304 stainless steel for its built-in exteriors and major cooking components across the line, with the Professional Series using cast 304 stainless burners rather than formed tube. Component-level detail is in each model’s manual, and we will send the current documentation for any specific unit before you order.
Ask us what a grill is actually made of
We would rather answer a materials question than sell you the wrong appliance for your environment. Tell us where the island is going — near the coast, beside a pool, under cover, inland — and we will tell you what matters for that specific situation and send the manufacturer documentation to back it up.
Prefer email? Reach us at info@smokeforges.com
Related reading: Built-In vs. Freestanding Grill, Built-In Grill Cutout Dimensions, and Natural Gas vs. Propane. Browse the KoKoMo built-in collection and outdoor kitchen components.
