How to prepare a metal surface before spray painting

Spray painting is an effective way to protect and enhance metal surfaces. To achieve a durable and even result, it is essential to prepare the surface carefully before painting. In this article, we go through all the necessary steps to help you achieve the best possible finish.

Choosing the right materials

Before starting the painting process, it is important to choose the right materials. Maston Hammer Smooth and Hammer Hammered metal paints are excellent choices for all metal surfaces except galvanised steel. These spray paints provide a 3-in-1 solution: rust protection, primer and topcoat in one easy package. However, removing excess rust before painting is recommended to improve the durability of the final finish.

Below is an instructional video on how to use Maston Hammer spray paint.

Always ensure you are working in a well-ventilated area or outdoors before you begin.

Cleaning and degreasing the surface

The first step in surface preparation is thorough cleaning. Remove all dirt, dust and grease from the metal surface. This can be done using Maston Degreaser, soapy water with a brush or a pressure washer. Allow the surface to dry completely before moving on to the next stage.

Degreasing is particularly important, as grease and oil can prevent the paint from adhering properly. Use a degreaser or an acetone-based cleaner and wipe the surface clean with a microfibre cloth. Ensure all grease has been removed before proceeding.

If the surface has old paint that is flaking or peeling, it must be removed. This can be done by scraping or using a chemical paint remover. Again, make sure the surface is fully dry before continuing.

Sanding and roughening when required

Sanding is an important part of surface preparation because it helps the paint adhere more effectively. Use fine-grit sandpaper (120–220 grit) and sand the surface lightly. This removes small imperfections and creates a slightly rough texture that improves adhesion.

Once you have sanded the surface, remove all sanding dust. This can be done using a vacuum cleaner or a damp cloth. It is essential that the surface is completely dust-free before painting to ensure an even finish.

If you are dealing with a rusty surface, remove all loose rust with a wire brush or sandpaper. Removing excess rust improves the durability of the paint.

Applying primer when necessary

Typically, a primer is applied before painting, but when using Maston Hammer Smooth or Hammer Hammered metal paints, a separate primer is not required. If the metal surface has been cleaned of grease, dirt and excess rust, you can spray paint the surface directly without an additional primer.

If you are using a paint that does not contain a built-in primer, follow the instructions below.

In other cases, primer is an important part of the painting process as it improves adhesion and durability.

Apply the primer according to the instructions. Thin, even coats are usually recommended to avoid drips and unevenness. Allow the primer to dry completely before applying the topcoat.

Once the primer has dried, inspect the surface carefully. If you notice any imperfections or runs, sand them lightly and remove the sanding dust before applying the next coat. This ensures a smooth and durable finish.

When the surface is ready

After completing all these steps carefully, you are ready to begin spray painting the metal surface. A well-prepared surface ensures that the paint adheres properly and lasts, providing both protection and a visually appealing finish.

Remember, thorough surface preparation is the key to a successful painting project. By following these steps, you ensure a durable and professional result.

If you are located outside of Finland, please check your local retailer for the products. Online store delivery is only available within Finland.