What are the Best Methods for Painting Galvanized Steel?

Patrick Roland

Galvanized steel is one of the most durable metals on the market and is used for everything from industrial structures to playground swing sets. One of its major drawbacks, however, is its susceptibility to corrosion. Luckily, properly cleaning and painting galvanized steel will keep the metal from wearing down. Professionals utilize three different methods when applying corrosion protection to steel: spray painting, hand painting and powder coating.

An unpainted galvanized steel bucket.
An unpainted galvanized steel bucket.

Before a drop of paint is applied in any form, each steel surface must be properly cleaned. The first step, no matter if the metal is corroded or brand new, is to sand it with a thick-grit sandpaper. Apply pressure until any bumps or irregularities are removed. Next, clean the entire surface with soapy water and rinse, letting the metal completely dry. Finally, purchase a galvanized metal primer and apply it to the entire surface.

Painting galvanized steel by hand can provide a thicker coating.
Painting galvanized steel by hand can provide a thicker coating.

With this preparation, any one of three techniques can be used for painting galvanized steel. The most popular method for a small project, like a swing set, is to spray paint the surface. There are several commercial paints, in many different colors, available for this job at painting supply stores. Simply spray the paint evenly over the surface until it dries. If runs or streaks appear, sand them down and reapply paint until smooth.

Galvanized metal is a type of metal is coated with a protective layer of zinc that protects it from rust and corrosion due to exposure to the elements.
Galvanized metal is a type of metal is coated with a protective layer of zinc that protects it from rust and corrosion due to exposure to the elements.

Larger jobs, like railings and walkways constructed from galvanized metal, require hand painting. Professionals recommend polyurethane, epoxy or enamel paint in order to best protect against corrosion. Using a brush or roller, apply the paint in even strokes so every aspect of the exposed steel is covered. Painting galvanized steel by hand usually protects the metal from the elements better than spray painting because the coating is thicker and more weather-resistant.

Using a paint roller is ideal for applying even coats of paint to galvanized steel.
Using a paint roller is ideal for applying even coats of paint to galvanized steel.

A third method for painting galvanized steel, usually reserved for large jobs, is called powder coating. The first step in powder coating is applying a layer of zinc across the entire metal surface. This application provides a protective buffer against weather and temperature, so the metal will not corrode easily. The second step of this process is blowing a powder over the zinc until it coats the entire metal surface and then heat curing it. The curing process bonds the powder to the metal and also brings out the chosen color of the powder.

Some galvanized metals, such as cable or wire, may require a number of thin coats to cover evenly.
Some galvanized metals, such as cable or wire, may require a number of thin coats to cover evenly.
Playgrounds are often painted bright colors to appear more attractive and exciting to young children.
Playgrounds are often painted bright colors to appear more attractive and exciting to young children.
Spray painting is often used to paint large areas of galvanized steel.
Spray painting is often used to paint large areas of galvanized steel.
Powder coating is often used to color and protect galvanized steel surfaces in an industrial setting.
Powder coating is often used to color and protect galvanized steel surfaces in an industrial setting.
Galvanization -- the applying of protective zinc coatings to steel or iron -- is often performed using special machines at production factories.
Galvanization -- the applying of protective zinc coatings to steel or iron -- is often performed using special machines at production factories.

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Discussion Comments

Soulfox

A good number of "amateur" projects in which galvanized steel is painted with a brush winds up looking horrible. Often, it looks like a broom was run through the paint -- streaks like crazy and leaves a rough, ugly finish.

Is the phenomenon due to the paint used, the brush used or something else entirely.

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