‌How to Choose Coating Thickness for Architectural Pre-painted Steel Plate

Microscopically, the coatings on pre-coated metal panels contain micropores. Corrosive agents in the air, such as water and chloride ions, can penetrate through these micropores, scratches, or weak points in the coating, leading to under-film corrosion. This eventually causes issues like blistering and peeling. Therefore, selecting the appropriate coating thickness is critical: thicker coatings more effectively block moisture and corrosive agents. However, cost-effectiveness must also be considered. Based on comparative performance tests for different coating thicknesses, the following recommendations apply:

• ‌PE polyester coatings‌, ‌HDP high-durability coatings‌, and ‌SMP silicone-modified polyester coatings‌: A combined primer and topcoat thickness of ‌≥20 μm‌.
• ‌PVDF fluorocarbon coatings‌: A combined primer and topcoat thickness of ‌≥25 μm‌ (due to their higher durability requirements).
• ‌Backside epoxy coatings‌: Minimum ‌5 μm‌. For indoor environments with severe corrosion, a ‌dual-layer backside coating‌ with a thickness of ‌≥10 μm‌ (or thicker) is recommended.

In highly corrosive environments, moderately increasing the coating thickness enhances resistance to corrosive agents and extends the panel’s service life.