Common household products like Comet, mineral spirits, and chlorine bleach can all be used to prepare galvanized steel for painting. If you’re attempting to paint siding panels, roof flashing, or other materials that have seen exposure to the elements, a thorough cleaning is necessary to eliminate any organic contaminants from the outer surface. [1] X Research source
If possible, do your prepping and painting indoors, or on a clear day when there’s little moisture in the environment.
Afterwards, wipe the surface with a cloth dampened with warm water to remove any lingering dust. < This chalky substance is commonly known as “white rust. ” It forms when the thin layer of zinc coating the steel begins to break down as a result of age or exposure to the elements. [4] X Research source
The acid in the vinegar will gently etch the slick zinc-coated finish, giving it a rougher texture that will allow paint to stick better. If you happen to miss a spot, you may end up with splotchy, peeling paint.
If you’re short on time, wait until the surface is dry to the touch before moving on to priming and painting.
For maximum hold and durability, choose a multipurpose latex primer that’s designed for exterior use. If the steel is destined for rough industrial or outdoor conditions, consider upgrading to a high-performance epoxy primer. Epoxy primers offer a semi-permanent hold, and are resistant to scratching, chipping, and peeling.
Applying paint to wet primer will hinder its ability to stick.
For the most dependable results, look for paints that are formulated specifically to bond to galvanized steel. The enamels in alkyd paints can react with the slick zinc finish on a galvanized steel surface, leading to poor adhesion and peeling.
A roller may come in handy for applying paint to broad surfaces like siding and roof panels.
Expect drying times to be longer in warm, humid conditions.
Indirect airflow from a box fan or air conditioning unit may help the topcoat set up faster. Once the topcoat is dry, you can go ahead and install the piece or put it to its intended use.
When properly applied, the paint job on your galvanized steel will enjoy a long lifespan and be more resilient to extreme conditions.
