Painting galvanised surfaces

One of the protective processes for preserving iron/steel is to electrically coat the metal with zinc. This creates a surface of zinc plates to give a “fish scale”, or overlapping effect to preclude water/moisture from creating an electrolyte and thereby prevent oxidisation of the iron/steel.

However, this plating process also causes problems where a paint system is to be applied. On a boat trailer for example the normal course of action is to leave it to naturally weather for up to 24 months by which time the platelets would have oxidised to leave a dull flat surface. At that stage, a solvent degrease and final wash over with hot water, then a final wipe down with NORCLEAN-PLUS is usually sufficient prior to prime coating.

Where the weathering process of up to 2 years has not been allowed to occur the consumer often gets impatient, coats the metal over, and then finds a few months later, all of the paint is peeling off. In many cases, the cause is the result of using the wrong paint products… without knowing why.

Learn why the selection of paint, and see our recommendations for primers and finish coats.