➕ Alkyd Zinc Chromate Primer
This paint contains anti-rust chromate pigments, which act as a rust cover for metal structures such as metal skeletons of warehouses, etc. To ensure better penetration of this paint into the structure and to enhance its resistance and adhesion, using a brush for painting is recommended. This paint should not be used for structures that are submerged in water because the pigments present in this paint can make the paint toxic when in contact with water.
➕ Alkyd Zinc Phosphate Primer
This paint contains anti-corrosion phosphate pigments, making it suitable for painting various metal structures, such as prefabricated metal skeletons, etc. The use of this paint increases the structure’s resistance to weather factors and moisture. This paint can be used as an initial or intermediate layer on metal structures. It is recommended to use a brush to enhance the penetration and adhesion of the paint.
➕ Matte Alkyd Topcoat
One of the commonly used paints for painting metal structures is the matte alkyd topcoat. Various tools such as brushes, rollers, and spray guns can be used to apply this paint on metal skeletons. This paint possesses unique features, including good coverage, high stability, and quick drying.
➕ Glossy Alkyd Topcoat
The application of the glossy alkyd topcoat is similar to that of the matte alkyd topcoat. The only difference is that the glossy type has greater shine and color stability. This paint is primarily used for painting building railings, doors, windows, and metal installations.
➕ Anti-rust Paint
Anti-rust paint is also known as alkyd primer. This product is designed for painting metal surfaces and possesses anti-corrosion properties. One of the main features of the anti-rust paint is its high adhesion, long-lasting durability, suitable coverage, and quick drying.
✅ Determine the Type of Surface of the Metal Structure
Before painting any metal skeleton, you must determine the type of surface. This means whether the surface has been previously painted or if it is the first time you are going to paint it. For new warehouses, it is advisable to sandblast the parts before painting.
✅ Condition of the Structure’s Surfaces
If the surface of the metal skeleton is decayed, rusted, or cracked before painting, necessary repairs must be made first, and then painting can occur. If you paint the structure despite these issues without addressing the repairs, the surface may get damaged in the near future, and you may not achieve good results from the painting.
✅ Number of Paint Layers
If the number of paint layers and their thickness is high, the resistance and durability of the paint will increase. Therefore, it is necessary to consider the type of paint and the number of layers required for painting the structure.
✅ Cost Considerations
Before painting, you should consider the cost of this work. The tools and equipment used for this purpose vary and come with different costs. Therefore, it is essential to make necessary estimates regarding the cost of painting the metal skeleton in advance and choose the best painting method based on the budget you have.
What Steps Are Taken for Painting the Metal Skeleton?
According to this guideline, the painting steps should be carried out in the following order:
➕ Step One: Clean the Metal Surfaces
One of the crucial points to observe in painting a metal skeleton is that before starting the painting, the metal surface must first be degreased. After that, rust removal should be done using manual brushes, electric brushes, and sandblasting equipment. If the metal skeleton has been previously painted, it must be thoroughly scraped to repaint it effectively.
➕ Step Two: Use Pre-Coating Primers
After completing the first step, it’s time to apply primers. Primers are used to prevent rusting of the metal skeleton, and they also enhance the adhesion of the paint to the metal. If you couldn’t remove all the rust in the first step, cover the metal surface with a chromate primer.
➕ Step Three: Apply the Undercoat Paint
In this step, after applying the primer on the metal, you need to apply an undercoat paint. Epoxy resin can be used in both the intermediate and final stages as a separate layer of paint, or it can be mixed with the paint.
➕ Step Four: Apply the Intermediate Coat
To reinforce the base coat, another layer of painting is applied. The application of the intermediate coat plays an essential role in the effectiveness and quality of the final paint.
➕ Step Five: Apply the Final Coat
The application of the final coat is similar to the previous painting steps. At this stage, you can either mix the final layer with epoxy resin or perform the painting separately.
Painting Methods for Metal Skeletons
✅ Using a Brush for Painting
Painting a metal skeleton with a brush is considered a method that requires a significant amount of time and cost. Although newer methods have emerged today, this approach still has its specific followers. This is because it has advantages such as maintaining the inherent moisture of the metal surface. The environmental pollution level in this method is lower than in other methods, and the paint layers adhere better to the metal.
✅ Using a Roller for Painting Metal Skeletons
Another tool used for painting metal skeletons is a roller. Painting with a roller is generally faster than with a brush. This tool is extensively used for painting flat surfaces; however, it cannot effectively paint areas with recesses or corners of the structure.
✅ Using an Airless Sprayer
The airless sprayer is another piece of equipment used for painting metal skeletons. In this method, painting the metal surfaces is done without air and bubbles. Using this tool reduces paint waste to only 10 to 20 percent; additionally, painting the metal structure is executed efficiently and quickly, and the painting tools do not wear out.
Calculating Paint for Metal Skeletons
It should be noted that the paint thickness for metal skeletons varies in different environmental conditions, as follows:
✔ Paint Thickness in Moderate Environments
In moderate environments where the relative humidity is less than 50 percent, the paint on the structure’s surface should have a thickness of 40 microns. In enclosed but open environments, 40 microns of alkyd primer and 40 microns of alkyd topcoat are used. In open environments exposed to weather conditions, 40 microns of alkyd primer, 40 microns of alkyd intermediate layer, and 40 microns of alkyd topcoat are applied. In moderate environments where steel components are used inside walls or plastering, 40 microns of anti-corrosion paint should be used.
✔ Paint Thickness in Harsh Environments
In harsh environments with humidity levels above 80 percent and an industrial atmosphere, up to 60 microns of paint thickness can be used in open environments. For this purpose, 60 microns of zinc-rich epoxy primer and 60 microns of epoxy for the intermediate layer can be applied, along with 60 microns of polyurethane epoxy for the topcoat. In enclosed but open environments, all three layers should have a thickness of 40 microns, and steel components used in walls or plastering need 40 microns of zinc-rich epoxy primer.
✔ Paint Thickness in Very Harsh and Coastal Environments
In very harsh environments where chlorine gas is present, the paint layers in enclosed and open environments should have 60 microns of zinc-rich epoxy primer, 60 microns of epoxy intermediate layer, and 60 microns of polyurethane epoxy topcoat. Steel components used in walls or plastering should have approximately 40 microns of zinc-rich epoxy primer and 40 microns of epoxy topcoat.
✔ Paint Thickness in Normal Environments
In normal environments where the warehouse is used as a storage area, the paint thickness includes a single 20-micron layer.
✔ Final Layer Painting
To determine the thickness of the paint layer and primer coating, special equipment is used, and measurements are taken with a magnetic gauge in various locations. Accordingly, the paint thickness in each measurement should not be less than 80 percent.
Important Tips for Painting Metal Structures
When painting metal structures, consider the following:
- Before painting, ensure that the surfaces of the metal skeleton are thoroughly cleaned and dried to improve paint quality.
- To prevent “crocodiling” (the formation of cracks in the paint), purchase quality primers and topcoats from the factory.
- After painting the metal structure, protect it to prevent dust accumulation on the surface.
- Use the paints obtained from the factory according to the manual and based on weather conditions.
- Conduct painting in suitable, covered environments.
- If the thickness of the structure does not meet the painting guidelines, it should be repainted.
- Avoid painting in cold, dark, and humid weather. If the temperature difference between the environment and the dew point is less than 5 degrees or if the humidity is above 80 percent, painting should not be performed.
