Industrial Coating: From Surface Preparation to Topcoat Spraying, Every Step Affects Coating Durability

Industrial Coating: From Surface Preparation to Topcoat Spraying, Every Step Affects Coating Durability

Industrial coating is by no means a simple "painting job"; it is a systematic process ranging from surface preparation to topcoat spraying. The quality of operation in each link directly determines the adhesion, rust resistance, and service life of the coating. Any oversight in a single step may lead to premature failure of the coating.

Surface preparation is the foundation for the coating to "take root" and directly impacts adhesion. First, it is necessary to remove oil stains, rust, and oxide scales from the workpiece surface — if oil stains are not completely removed, the coating will form "cratering" as it fails to adhere tightly to the metal surface; residual rust will continue to spread under the coating, causing blistering and peeling later. Common processes such as sandblasting and pickling can create a uniform rough texture on the workpiece surface, like creating "gripping points" for the coating, significantly improving adhesion strength. Additionally, after surface preparation, a primer must be applied promptly to prevent secondary rusting of the workpiece during exposure. The interval for this step should usually be controlled within 4 hours, and even shortened in humid environments.

The intermediate coating plays a key "connecting" role, determining the flatness and impact resistance of the coating. After the primer dries, it is necessary to sand the surface to remove defects before spraying the intermediate coat — the intermediate coat not only fills small depressions in the primer to make the paint surface smoother but also increases the coating thickness, enhancing scratch and impact resistance. If the intermediate coat is insufficient in thickness or not thoroughly sanded, "pinholes" are likely to appear after topcoat spraying. Moisture and impurities can seep through these pores, accelerating coating aging.

Topcoat spraying is the "final defense line," directly related to weather resistance and appearance. Before spraying, the coating viscosity and spray gun pressure must be adjusted to ensure uniform atomization and avoid defects such as "runs" and "orange peel"; the topcoat thickness must be strictly controlled — for example, the topcoat of outdoor equipment usually needs to reach 80-120 microns to effectively resist UV radiation and rain erosion. Meanwhile, after spraying, the coating must cure at the specified temperature (usually 15-30°C) and humidity (40%-60%). Insufficient curing time will result in insufficient film hardness, making it prone to wear and peeling.

From surface preparation to topcoat application, every step of industrial coating is closely linked. Only by strictly adhering to the standards of each link can the coating truly function as a "protective armor" and extend the service life of the equipment.