Manual coating of bus & truck

Yes, paint properties strongly influence how well it penetrates complex shapes. In simple terms, a thicker paint tends to form heavier, more “ballistic” droplets that are harder to carry into cavities and hidden areas, while a paint that flows more easily breaks into finer droplets and follows the air more effectively.

This is where the Fpro gun makes a real difference. Thanks to its Restrictor and Vortex features, it increases shear right inside the gun during spraying. This activates the paint’s natural thixotropy, meaning it temporarily becomes less viscous exactly when it is atomized. The result is easier spraying, finer droplets, and much better penetration into recesses, complex shapes and onto free-edges.

Airspray technology is particularly well suited for coating complex shapes, cavities and free-edges because it combines fine paint droplets with a strong airflow that carries the paint into difficult-to-access areas. Compared with Airless or Airmix® technologies, it produces lighter, less ballistic droplets that follow the air stream more easily, improving penetration into cavities, edges, threads, and complex chassis shapes. This leads to more uniform coverage and consistent film thickness, even on complex and hidden surfaces.

Edge corrosion is one of the most common starting points for coating failure in industrial equipment. Sharp edges naturally create weak spots where protective coatings tend to become thinner, making them more vulnerable to moisture, chemicals, abrasion, and harsh environmental conditions.

This issue is not caused by a single factor, but by the combination of part geometry, coating formulation, surface preparation, application process, and curing behavior. Physical effects such as surface tension and flow behavior often lead to reduced film thickness at edges compared to flat areas.

Because of this, edges act as a “Trojan horse” for corrosion: a small, localized weakness that can progressively spread and compromise the durability of the entire structure. This is why modern coating strategies increasingly focus on improving edge build and ensuring consistent protection across the full geometry of the part.

Electrostatic spraying is generally not the best option for parts with deep cavities, recesses, or highly complex shapes. While it is very efficient on open and well-exposed surfaces thanks to its high transfer efficiency, it is strongly affected by the Faraday cage effect.

In practice, the electrostatic field tends to wraparound external edges but becomes ineffective inside confined or recessed areas. As a result, paint is naturally repelled from cavities, leading to poor penetration and uneven coverage in these zones.

For this reason, electrostatic technology is typically limited to simpler or more open shapes, while air-based spray technologies are preferred when reliable coverage of complex internal shapes is required.