Editing Rust (section)

=== Galvanization ===
{{main|Galvanization}}
[[Image:Rust from bathtub in Kyiv.jpg|thumb|Interior rust in old galvanized iron water pipes can result in brown and black water.]]

Galvanization consists of an application on the object to be protected of a layer of metallic [[zinc]] by either [[hot-dip galvanizing]] or [[electroplating]]. Zinc is traditionally used because it is cheap, adheres well to steel, and provides [[cathodic protection]] to the steel surface in case of damage of the zinc layer. In more corrosive environments (such as salt water), [[cadmium]] plating is preferred instead of the underlying protected metal. The protective zinc layer is consumed by this action, and thus galvanization provides protection only for a limited period of time.

More modern coatings add aluminium to the coating as ''zinc-alume''; aluminium will migrate to cover scratches and thus provide protection for a longer period. These approaches rely on the aluminium and zinc oxides protecting a once-scratched surface, rather than oxidizing as a [[sacrificial anode]] as in traditional galvanized coatings. In some cases, such as very aggressive environments or long design life, both zinc and a [[coating]] are applied to provide enhanced corrosion protection.

Typical galvanization of steel products that are to be subjected to normal day-to-day weathering in an outside environment consists of a hot-dipped 85&nbsp;[[μm]] zinc coating. Under normal weather conditions, this will deteriorate at a rate of 1&nbsp;μm per year, giving approximately 85 years of protection.<ref>{{cite web |url= https://www.greenspec.co.uk/building-design/steel-corrosion-protection/|title= Steel corrosion protection - Durability - Structural steel|author=<!--Not stated--> |date= |website= greenspec.co.uk|publisher= greenspec|access-date= 2022-09-13|quote=For atmospheric corrosion, refer to the Galvanizers Association Millennium Map of average zinc corrosion rates. About 50% of England and Wales has a rate of under 1&nbsp;μm/year}}</ref>