What materials are recommended for coatings on a zinc substrate?
Dispersion paints are suitable for making coatings on a zinc substrate, dispersion varnishes, alkyd varnishes, PVC varnishes, made of chlorine sulphonated polyethylene, polyurethane and epoxy, asphalt, tar-epoxy and special paints with high adhesion to zinc. When selecting the appropriate coating materials, the requirements for the coating should always be taken into account.

It is planned to paint new roof gutters made of galvanized steel sheet. Please list the necessary steps, having regard to the materials needed The steps are as follows:
1) cleaning the substrate with an ammonia-based surfactant, thorough sanding with synthetic abrasive fleece and rinsing thoroughly with clean water;
2) primer painting from the outside with dispersion varnish;
3) surface painting from the outside with dispersion varnish;
4) primer painting from the inside with asphalt varnish;
5) surface painting from the inside with asphalt varnish.
Special paints with good adhesion to zinc are also suitable for painting the external surfaces of the gutters, PVC and acrylic varnishes.
In addition, polyurethane and epoxy varnishes can be used, however, these products are relatively expensive, a due to the anticipated chemical loads – are not necessary.
The internal surfaces of the gutters can also be painted with asphalt-epoxy varnishes, but also these products are relatively expensive.