The paint will enhance the galvanized coating. Painting galvanised metal is very easy as long as the right steps are carried out. Proper surface preparation may start with SSPC SP-1 Solvent Cleaning to remove oil/grease contamination. A very common cause for paint failure is poor adhesion of the coating over an un-roughened, un-dulled and excessively smooth galvanized surface. The vinegar is a mild acid which acts to etch the galvanized coating so the paint will stick.
How to paint galvanized metal. Galvanised steel is the process of steel that has been treated with an anti-corrosive zinc coating through being dipped in hot zinc. Galvanized steel is coated with a thin layer of oil and passivator that protects it from water and weather damage. This table comes from “Duplex Systems: Painting over Hot-Dip Galvanized Steel” which is available on the AGA’s website. Wipe the galvanized surface down with white vinegar. Painting over galvanizing is often referred to as a "duplex coating." A common enquiry our technical team receive from painting contractors or councils is how to paint galvanised steel.
Clean new galvanized metal surfaces with a water based cleaner/degreaser to remove any oil or and contaminants. Prime the surface with a primer made for metal. Go over the metal with a wire brush to remove any oxidation. Following a few tips when working with it can help you get the most out of paint for galvanized metal.The recommended first step is to prepare the surface to be painted by making sure it is smooth and then applying primer to the metal. Process for Painting Galvanized Steel. If you prefer to spend less time preparing the surface, then you should consider buying a paint designed specifically for the material to be painted. If galvanized metal is not prepared and painted properly, it will tend to peel over time.
You can identify galvanizing through it’s camouflage effect when unpainted. The following is a quick introduction for the process: Preparation of galvanized steel before painting.
It will act as a barrier protection for the galvanized material and subsequently the galvanized material will allow the paint to last longer because there is no underlying corrosion. Once the metal has dried, dampen a cloth with white vinegar and wipe the surface down. Newly galvanized metal is shiny and smooth with virtually no anchor pattern. For additional information on preparing after-fabrication hot-dip galvanized steel surfaces for duplex coatings, consult ASTM D 6386, Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting. For general painting of galvanized steel, here is an excellent list of paints and their compatibility with galvanized steel.