Material

# Wrought iron or coated steel: what actually changes

Many "wrought-iron look" obelisks are actually powder-coated steel. The material difference explains most of the gap in price and service life.

**2 min read** Estimated time **Material** Topic **12 October 2026** Published “Wrought iron” has become, in retail, an almost decorative label — many products sold under that name are actually steel, simply painted to evoke the look. The material difference isn’t just a matter of vocabulary.

## Three ways to protect the metal

**Galvanising** (dipping in a molten zinc bath, around 450°C) deposits a zinc layer that acts as a sacrificial anode: it corrodes in place of the steel and protects the metal as long as the coating isn’t fully consumed. Very little maintenance while the coating is intact.

**Powder coating** (polyester powder paint, oven-cured) mostly protects at the surface, with good UV resistance and good colour retention — but once the film is scratched through to bare metal, rust can start underneath.

The **duplex system** (galvanising followed by powder coating) combines both: according to surface-treatment industry technical sheets, combined service life can reach up to 2.5 times that of either treatment taken alone.

> Comparison sourced from surface-treatment industry technical sheets (the metalwork sector) — no single standard governs this comparison; it reflects a consensus among industry sources.

## Check the material before comparing two prices

A thin powder-coated steel obelisk costs noticeably less than a solid wrought-iron piece — unsurprising, since it needs less raw material and less shaping time. The problem isn’t the lower price itself, but comparing two “wrought-iron look” obelisks at very different prices without checking the actual material: they don’t necessarily match in service life.

## What it changes in practice

A thin steel piece bends more easily under the weight of a mature climbing plant — a fully grown rose or wisteria represents a real load over time. Solid wrought iron, heavier and more rigid, holds up better under that stress, and its protection (galvanising or duplex) lasts longer outdoors.

## Frequently asked questions

   How can I tell if an obelisk is wrought iron or coated steel?
Weight and bar thickness are good indicators — a solid wrought-iron piece is noticeably heavier than a thin-steel model. When in doubt, ask the seller for the exact material and finish type.
   Is powder coating alone enough outdoors?
It protects well as long as the paint film isn’t scratched through to bare metal — but without galvanising underneath, a scratch exposes bare steel to rust faster than a duplex system would.
   Is the duplex system worth its higher price?
For an outdoor piece exposed to the elements over several years, the extended service life (up to 2.5 times that of a single treatment, per industry technical sheets) generally offsets the higher upfront cost.

Read next

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