How to Choose Zinc Coating for Galvanized Steel Wire
Hot-dip galvanizing coats steel wire in a layer of zinc that protects it from corrosion. The heavier the zinc coating, the longer the wire lasts — so choosing the right coating weight is the key decision when specifying cable-armouring wire.
Who this guide is for
Cable manufacturers, mesh and fencing producers, and buyers specifying galvanized steel wire who need to choose a zinc coating that balances corrosion life against cost.
Why coating weight matters
Zinc coating is measured as coating mass in grams per square metre (g/m²). A heavier coating gives a longer service life, especially in wet, buried or marine environments, because there is simply more zinc to corrode before the steel is exposed. A lighter coating costs less and suits dry, indoor or short-life applications. Because the coating protects the steel sacrificially, the right weight is a trade-off between service life and price.
Common coating-weight classes
| Coating class | Typical coating (g/m²) | Typical use |
|---|---|---|
| Light | ≈ 15–100 g/m² | Indoor or short-life, cost-sensitive cables |
| Medium | ≈ 100–230 g/m² | General power & telecom cable armouring |
| Heavy | ≈ 230–300+ g/m² | Submarine, offshore and long-life buried cables |
Indicative only — exact coating weight depends on wire diameter and the standard you work to (e.g. ASTM A641, EN 10244-2). Send us your spec and we'll confirm the class.
How to choose the right coating — step by step
- Define the environment. Indoor/dry, general outdoor, buried, coastal or submarine — corrosion risk rises across that list.
- Set the design life. A longer required life needs a heavier coating.
- Pick a coating class from the table above that matches the environment and life.
- Confirm against the standard. Your cable standard (ASTM A641, EN 10244-2, BS EN 10257) may fix the coating class by wire diameter.
- Confirm diameter and tensile grade — heavier coatings and finer diameters interact, so the mill confirms the achievable combination.
Common mistakes to avoid
- Specifying a light coating for buried or marine cable — it corrodes long before the design life.
- Quoting coating thickness (µm) instead of coating mass (g/m²); galvanized wire is specified by mass.
- Ignoring the diameter–coating relationship — the same class can mean different g/m² at different diameters.
- Not naming the standard, which leaves the coating class open to interpretation.
Coating and the standard
Coating classes are defined in standards such as ASTM A641, EN 10244-2 and BS EN 10257. Naming the standard in your enquiry removes ambiguity — Zhongbo manufactures and tests to it, and can also work to a customer-specific coating requirement.
Zinc coating FAQ
What zinc coating is standard for cable-armouring wire?
There is no single fixed weight — it is set by your cable standard and the environment. General power and telecom armouring often uses a medium class (about 100–230 g/m²); buried, coastal or submarine cable uses a heavy coating (about 230–300+ g/m²).
Is zinc coating measured in g/m² or microns?
Galvanized wire coating is normally specified as coating mass in grams per square metre (g/m²), not thickness in microns. A heavier coating mass means a longer corrosion life.
Can Zhongbo match a specific coating class?
Yes. Tell us the coating weight, or the standard and environment, and we will manufacture and test to it — with a mill test certificate covering coating weight on every batch.
