The number-one reason wire fence fails early is not the steel — it is the zinc. Too little zinc and the fence rusts within a season; the right coating and it lasts for decades. For overseas buyers, a widely used benchmark is zinc coating standards, which cover zinc and zinc/aluminium-alloy coatings on steel wire.
Why zinc coating matters
Galvanising protects steel wire in two ways: it seals the steel from moisture, and it corrodes sacrificially — the zinc gives itself up before the steel underneath does. The more zinc per square metre, the longer that protection lasts. This is why a heavier coating is worth paying for in wet, coastal or high-humidity environments, and why the cheapest fence on a quote is often the most expensive over its life.
What zinc coating standards actually are
Zinc coating standards set out coating mass classes and the test methods used to verify them for zinc-coated steel wire. In plain terms, they give buyers and factories a common language for "how much zinc, measured how." They are specifications you can build a fence to — not automatic stamps every product carries. We can supply field fence, barbed wire and Y posts to your required specifications on request; if your project calls for it, say so up front and we'll quote and test against it.
Coating weights explained
Zinc coating is measured in grams per square metre (g/m²). Common options are 40, 60, 100 and 200 g/m². As a rough guide:
- 40–60 g/m² — economical, suited to drier inland conditions or a shorter design life.
- 100 g/m² — a strong general-purpose choice for most rural fencing.
- 200 g/m² — heavy-duty, for coastal, high-rainfall or maximum-life applications.
There is no single "correct" weight — it is a trade-off between upfront cost and how many years you need the fence to stand. Buying 200 g/m² for a dry inland boundary wastes money; buying 40 g/m² for a coastal run wastes the whole fence.
Electro-galvanised vs hot-dip galvanised
How the zinc is applied matters as much as how much. Beware thin electro-galvanised wire — it carries a light zinc layer that can rust in a single season. Hot-dip galvanising (HDG) applies a much thicker, more durable coat, which is why we hot-dip our field fence, barbed wire and Y posts. If a quote looks unusually cheap, check whether it is electro-galv with a low coating weight — the price difference usually disappears the first time you replace it.
Matching coating to your environment
| Environment | Suggested coating |
|---|---|
| Dry inland, shorter design life | 40–60 g/m² HDG |
| General rural / mixed conditions | 100 g/m² HDG |
| Coastal, high-rainfall, long life | 200 g/m² HDG |
These are starting points, not rules — tell us your location and how long the fence has to last, and we'll recommend a coating.
How long does galvanised fence actually last?
There is no single number, because life depends on coating weight and environment together. As a rule of thumb, a heavier hot-dip coating in a dry inland setting can last decades, while a thin electro-galvanised coat near the coast may show red rust within a year or two. Zinc corrodes at a roughly predictable rate for a given atmosphere, so broadly speaking, doubling the coating weight doubles the time before the steel underneath is exposed. That is the whole economic case for paying for zinc up front — you are buying years of service life.
Three common zinc-coating mistakes
- Comparing price without comparing coating. Two quotes for "galvanised field fence" can differ several times over in zinc weight. Always compare g/m², not just the headline price.
- Assuming "galvanised" means hot-dip. It might be a thin electro-galvanised coat. Ask which process was used and what weight was applied.
- Under-specifying for the coast. Salt air is brutal on zinc. If you are within sight of the sea, default to the heaviest coating you can justify.
Always ask for a test report
Whatever a label claims, ask your supplier for a zinc-coating test report rather than taking the number on trust. A reputable factory tests every order for zinc coating, wire diameter and tensile strength, and can provide documentation on request. We include test reports with the order and supply to your required specifications when specified.
Coating is only one half of choosing a field fence — the knot type is the other. If you haven't picked a knot yet, read hinge joint vs ring lock. And if you are importing for the first time, our guide to importing wire fence from China covers how to verify a factory's claims before you pay.
Need a specific coating?
Tell us your environment and design life and we'll spec the right zinc weight, with a test report on the order. Browse the full field fence specifications or send your requirements below.
