I often have metal gates galvanized and are required to give the final product a coat of paint.
As is known about galvanized metal, the zinc begins to oxidize with the air and creates the flaky powder which repulses the paint thereby flaking off the paint.
I have been told many things about galvanizing and how to paint / prepare for painting and was wondering if there is a generally accepted best practice here. What i have heard is the following:
- you need to wait at least a month to get the galvanized layer to oxidise, then paint
- you need to prepare the surface with a mild acid to remove oils (either vinegar or galvanized metal cleaner)
- do not use oil based paints (either primer or paints) since the oil does not adhere to the coating
- paint first with an etch primer which will etch and bond to the surface, then paint
- forget primers and just apply two coats of acrylic paint which bonds well to the surface.
I guess, as with any paint application surface preparation is key, just interested to know what the professionals do here.