What is galvanizing?

Galvanizing is the application of a thin metal layer, usually zinc, by electrolytic means onto a metal object in order to protect it against corrosion.

How it works

In galvanizing, the object is suspended in a bath containing a metal salt solution and connected to an electric current. Through electrolysis, metal particles, usually zinc, attach evenly to the surface. This creates a thin, uniform protective layer. The zinc forms a barrier against moisture and oxygen and also acts as a sacrificial material: it corrodes before the underlying steel, keeping the base material protected.

Strictly speaking, galvanizing refers to this electrolytic zinc coating. Colloquially, hot-dip galvanizing, immersing steel in molten zinc, is often called galvanizing as well. Hot-dip galvanizing produces a thicker layer and therefore longer protection, while electrolytic zinc coating gives a thinner, smoother finish.

Application

In construction, fasteners such as screws, bolts and nails are commonly galvanized, as are fittings and steel profiles. The zinc layer prevents these parts from rusting, even when exposed to moisture. Galvanized materials are therefore suitable for outdoor use and places with high humidity, where untreated steel would corrode quickly.

Related terms

• Corrosion
• Zinc
• Steel
• Anodizing

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