SteelHow each coating is applied
Hot-dip galvanizing immerses the steel in molten zinc, in a bath at about 450 °C. The zinc alloys with the steel surface, so the coating bonds to the steel as zinc-iron layers under an outer layer of zinc.
Electro-galvanizing is an electrolytic process. The steel is the cathode in a zinc-containing solution, and an electric current deposits a layer of zinc on it. No molten metal is involved.
Coating thickness
The thickness figures below are for galvanized steel in general, as quoted by several sources. They are not values from a wire standard, and the quoted ranges differ from source to source.
| Process | Typical thickness | Range quoted by sources |
|---|---|---|
| Hot-dip | about 50 to 100 µm | 45 to 200 µm |
| Electro-galvanized | about 5 to 15 µm | 5 to 25 µm |
For wire, the coating is usually specified as zinc mass per square metre of wire surface, in g/m², rather than as a thickness. See zinc coating classes for how EN 10244-2 and ASTM A641 do this.
Corrosion life
Zinc protects steel as a barrier against air and moisture, and it corrodes first where the coating is scratched. How long that protection lasts depends on how thick the zinc layer is and on the environment. Sources agree that the thicker hot-dip coating generally resists corrosion better than a thin electro-galvanized coating. The lifetimes they quote vary widely with the environment, so this page gives no number of years.
Typical uses
General sources place hot-dip galvanizing on items used outdoors, such as road fences and power towers, and on structural materials. Electro-galvanizing is placed on small components and on items used indoors, such as household appliances.
For wire, hot-dip galvanized wire is the choice when the wire has to hold up against weather or moisture, for example in tying and binding in construction and in agriculture. Our hot-dip galvanized wire page lists its diameter range, coating weight and standards.
Questions to settle in a quote request
State the process you need, the diameter, and the coating as a class or a mass in g/m². Compare black annealed and galvanized wire in black annealed vs galvanized tie wire.
For the steps, specifications and shipping when you buy from abroad, read our page on galvanized wire supplied from Türkiye.
