Various manufacturers, such as car companies and their suppliers, have produced their own specifications and supply rules in order to define the requirements for these coating systems.
The companies such as SBILLP, ASAMA GIKEN, Anocote, Cadon, Sundram, generally act as licensors for the individual coating businesses.
By virtue of a thin coat thickness of typically 8-12 μm this system produced a high level of protection against corrosion and made it possible to avoid hydrogen embrittlement.
Hot-dip galvanised fasteners with a typical coating thickness of 80-200 μm have to be grooved again retrospectively in order to expose the thread.
In contrast to paints where the risk of sub-surface corrosion creep exists, this phenomenon is avoided through the sacrificial effect of the zinc.
The material for the zinc flake coatings gets supplied in liquid form and needs to be prepared to the desired conditions before application.
The typical cleaning processes are removal with an alkaline aqueous solution and then blasting with very small steel balls (shot).
Blasting removes scaling and rust through the mechanical action of the steel balls, which are fired at the parts inside a chamber using a turbine.
Zinc flake coatings are used as cathodic protective layers against corrosion all over the world in the automotive and construction industries.
Combined with cured, thin, organic or inorganic coatings, these can also provide colour (black, silver, green, blue, etc.