Galvanising is the process of applying zinc to products of steel or iron, to protect it from rust. There are various processes, each with their own corrosion resistance and finishing:
- Electro galvanising
- Dacromet / Geomet
- Thermal galvanising
Electro galvanising is suitable for applications indoors. A protective zinc coating is applied to the product using a galvanising process. It is pacified after the product has been treated. This can be done in a variety of colours: yellow, blue (shining chrome) and white (dull silver coloured).
Dacromet is an (environmentally friendly) process, wherein a mixture of a non-galvanising base of zinc, aluminium and chrome is applied to a product. The components are first beamed and degreased. The mixture is then applied (by manner of submerging). It is then centrifuged to remove the excess of coating after which the coating is hardened in a 300 degree oven. Dacromet has rust-resistant properties and has increased resistance against salt. It is often used in the maritime and automotive industry.
Geomet has a comparable composition to Dacromet, but without the Chrome. Because of this, it complies with the most recent EU guidelines for the environment. In Geomet, a zinc-aluminium strip coating is applied. This combines a minimal layer thickness with good protection against corrosion. Geomet is applied in different layers. This treatment is often used in the automotive industry.
The most sustainable manner of galvanising is thermal galvanising. The products are degreased and stained. They are then heated and submerged in a zinc bath. This zinc bath has a temperature of around 450 degrees. Thermal galvanising is very suitable for outdoor applications.
Example of Thermal galvanizing
Yellow Passivated casting