Hot-dip galvanizing = zinc coating, ~70–85 µm, self-healing at cuts, low maintenance → best for outdoor and industrial flooring. Painted = thin organic film, lower upfront cost, needs periodic re-coating → fine for dry indoor service only. For genuinely corrosive environments, switch the base material to stainless rather than relying on any coating.
One is a metallurgical zinc layer; the other is a surface film.
Hot-dip galvanizing immerses the fabricated panel in molten zinc, forming a series of zinc-iron alloy layers bonded to the steel. On grating sections this deposit is typically 70–85 µm thick and meets EN ISO 1461 (equivalent to ASTM A123). Because the zinc is metallurgically bonded and sacrificial, cut edges and welds stay protected even after fabrication — there is no film to scratch through to bare steel.
Paint is an organic coating applied over the steel. It protects only where it remains intact; once it is scratched, chipped or weathers through, the exposed steel corrodes. Paint systems vary widely in film build and chemistry, so performance is set by the specific system specified rather than by a single number.
Both finishes are described on the steel grating specifications page alongside untreated supply for temporary works.
Judged on the things that drive a flooring specification.
| Criterion | Hot-dip galvanized | Painted |
|---|---|---|
| Coating nature | Metallurgical zinc-iron layers | Organic surface film |
| Typical thickness | 70–85 µm (EN ISO 1461) | System-dependent film |
| Cut-edge / weld protection | Self-protecting (sacrificial) | None once film breaks |
| Service environment | Outdoor, industrial, humid | Dry indoor, benign |
| Maintenance | Minimal for years | Periodic inspection & re-coat |
| Upfront cost | Higher (bath + zinc) | Lower |
Galvanizing adds a process and material cost per tonne, but it removes the recurring re-coating cycle that a painted deck requires in any wet or industrial atmosphere. Over the asset life the galvanized route is usually the cheaper one for outdoor flooring.
The cheap option upfront is often the expensive option over 20 years.
A galvanized steel grating deck is effectively maintenance-free for a long period in atmospheric exposure: the zinc layer weathers slowly and, where it is locally damaged, continues to protect the surrounding steel. That removes access, scaffold, abrasive-blast and re-coat costs from the facility budget for years at a time.
A painted deck inverts that picture. The paint must be inspected, prepared and re-applied on a cycle, and grating is an awkward shape to coat — high surface area, open grid, edges — so each re-coat is labor-heavy. In a corrosive or wash-down plant, those cycles arrive sooner and more often.
When the environment is genuinely aggressive — chemical fumes, saline coastal air, food-acid wash-down — the right move is not a thicker paint but a different base material. The stainless versus galvanized comparison covers when 304 or 316 stainless pays for itself.
Our hot-dip galvanizing follows EN ISO 1461 (equivalent to ASTM A123). It specifies minimum zinc coating thickness by steel thickness — typically 70–85 µm on grating sections — plus coating adhesion and appearance requirements, delivering long-term corrosion protection for outdoor and industrial environments. The zinc layer sacrifices itself to protect the steel, so cut edges and welds remain protected even after fabrication.
Yes, but only with the correct preparation. Fresh galvanizing must be allowed to weather or be treated with a suitable etch primer so the paint adheres; painting directly onto bright zinc usually fails. In practice most operators choose one system or the other: galvanizing for self-protecting outdoor service, or paint for a specific color or indoor identification. A duplex (galvanize-plus-paint) system is possible where maximum life is required.
Painted (or untreated) carbon-steel grating is usually the lower upfront cost because there is no galvanizing bath step. Hot-dip galvanizing adds a process and a material cost per tonne. The economic question is total cost of ownership: a galvanized deck typically needs no maintenance for many years, while a painted deck must be inspected and re-coated on a cycle, which often makes galvanizing cheaper over the asset life for outdoor and industrial flooring.
Painted or untreated grating is acceptable for dry, indoor, benign-atmosphere service where there is no standing moisture and no aggressive exposure — for example enclosed plant rooms or temporary structures. Any location with rain, humidity, wash-down, chemical fumes or coastal air should use hot-dip galvanized carbon steel, or move to stainless base material where the environment is genuinely corrosive.