Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc. This stops oxygen and water reaching the metal underneath – but the zinc also acts as a sacrificial metal . Zinc is more reactive than iron, so it oxidises in preference to the iron object.

Why is zinc good at preventing corrosion?

Zinc protects steel from corrosion in two ways. Firstly, a zinc or zinc-containing separating layer creates a physical separation between steel and the corrosive environment. Zinc has the advantage that it forms a so-called patina on its surface, which significantly slows down the corrosion of the zinc itself.

How does zinc protect metal?

Through a process known as galvanic corrosion, zinc will “defer” to the metal that it’s protecting. … Zinc also acts as a sacrificial coating that protects the steel via galvanization. Steel will not corrode as quickly when covered with a zinc coating, even when a scratch or cut exposes the steel to air or moisture.