Aluminum Curtain Wall Panel Surface Treatments: Anodizing vs. Electrostatic Spraying
1. Anodizing
The surface treatment of curtain wall aluminum panels can be divided into two methods: anodizing and electrostatic spraying. Anodizing typically produces an oxide film of 12 μm or more, but the available colors are limited to bronze and white, resulting in a monotonous appearance.
A more serious drawback is the inconsistent color depth across individual panels. When many panels are combined to form a curtain wall, the overall effect is very unsightly. This drawback is virtually impossible to eliminate; it is not due to manufacturing defects, but rather because the aluminum panels, even from the same batch, have slight variations in chemical composition.
Furthermore, factors such as the current density in the electrolytic bath during anodizing cannot be perfectly controlled, leading to variations in color after oxidation. While these differences may not be noticeable on individual panels, they become very apparent when the panels are arranged together. Therefore, anodizing is not suitable for the surface treatment of aluminum curtain wall panels.
2. Electrostatic Spraying
Electrostatic spraying, on the other hand, is divided into powder coating and liquid coating. Powder coating materials mainly consist of polyurethane, polyester resin, epoxy resin, and other raw materials combined with high-color-fastness pigments, resulting in dozens of different colors of powder coatings.
This powder coating is impact-resistant and abrasion-resistant. Under a 50 kg impact, the aluminum panel may deform, but the coating remains intact without cracks or peeling. It is also resistant to dilute acids and mortar.
However, its drawback is that it is susceptible to long-term UV exposure, which can lead to color variations over time. Many domestic manufacturers produce powder coatings with significant weight variations. Some powders contain metallic particles, which can cause the wall color to change depending on the angle of sunlight, resulting in different shades during the day and at dusk.
Care should be taken when selecting powder coatings for aluminum curtain walls.
