The three options
Powder-coated mild steel is a steel frame with an epoxy powder coating baked on. It is strong, it can be finished in any colour, and it is the most economical option. Its protection is the coating: while the coating is intact the steel is fine, and where the coating is chipped or drilled, corrosion starts at that point.
304 stainless steel is the general-purpose austenitic stainless — the corrosion resistance is in the metal itself rather than in a layer on top, so a scratch does not start a rust bloom. It is the standard choice for indoor and most inland outdoor work.
316 stainless steel adds molybdenum, which is what makes it markedly more resistant to chlorides — salt air, salt spray, pool chemicals and many process chemicals. It costs more than 304 and earns that back in exactly the conditions where 304 begins to pit.
Choosing by environment
Work from where the unit physically stands, including what blows onto it. A turnstile under a canopy 200 m from the surf is a coastal installation.
| Where the unit stands | Sensible default | Why |
|---|---|---|
| Indoor lobby, climate controlled | Mild steel, powder coated — or 304 for appearance | No corrosion driver; the decision is aesthetic and budgetary |
| Inland outdoor (Gauteng, North West) | 304 stainless, or mild steel with a maintained coating | Rain and dust, no chloride load |
| Coastal (Cape Town, Durban, Gqeberha) | 316 stainless | Airborne chlorides attack 304 and find every coating defect |
| Mine, quarry, heavy industry | Mild steel for impact resistance, or stainless where washdown is chemical | Abrasion and impact often matter more than corrosion — and a coating can be repaired on site |
| Food, pharma, washdown areas | 304 or 316 stainless | Cleanability and chemical exposure; coatings fail at the wash lance |
The maintenance question nobody asks
Powder-coated mild steel is cheaper to buy and has an ongoing duty attached: inspect the coating, touch up chips before they spread, and pay particular attention to anywhere it has been drilled or cut on site. If the site has a maintenance regime, that is a perfectly sound arrangement and saves real money.
If the site has no maintenance regime — an unmanned gate, a remote perimeter, a building with no facilities team — then buying a finish that needs looking after is buying a problem. Stainless is the cheaper answer over the life of that installation even though it costs more on the invoice.
Stainless is not maintenance-free either. It stays passive because it is clean; in a marine or industrial atmosphere it wants periodic washing down, and it should never be cleaned with steel wool or with tools that have touched mild steel — the embedded iron particles rust and look exactly like the stainless has failed.
Appearance, and mixing the two
Brushed stainless reads as premium and suits corporate lobbies; powder coating lets the unit disappear into a colour scheme or carry a brand colour, which is often what a retail or stadium client actually wants.
It is also entirely reasonable to mix: a powder-coated frame with stainless fixings and wear parts, or stainless on the touched and exposed surfaces with mild steel behind. Because iMAT manufactures rather than imports, that is a specification choice rather than a special order.
Every unit in the iMAT range is offered in mild steel epoxy powder coated or brushed stainless steel, and mechanical parts on the turnstile range carry a ten-year guarantee. Browse the turnstile range or ask us to spec the finish for your position.
Common questions
Is 316 stainless steel worth the extra cost over 304?
In coastal, marine, pool or chemical environments, yes — the molybdenum in 316 is what resists chloride attack, and 304 will pit in those conditions. Inland and indoors, 304 is usually the better value.
Does powder-coated mild steel rust?
Not while the coating is intact. It rusts where the coating is damaged — chips, drilled holes, cut edges — so it suits sites that will inspect and touch up the finish, and suits unmanned remote positions poorly.
What finish should a turnstile in Cape Town or Durban have?
Coastal air carries chlorides, so 316 stainless steel is the safe specification for anything exposed. Indoor units well back from the entrance can usually be 304 or powder-coated mild steel.