During the production and application process, coatings may have various defects due to formulation, construction or environmental factors, affecting product performance and appearance. The following are the top 10 common defects in coating chemistry and their causes and solutions:
1. Imprint/Trace/Scar:
Defect manifestation: The paint film has different defects due to various reasons such as flash rust under the action of force. Specifically, when the paint film is observed at a 45° angle, the pattern or trace of the substrate is printed on the surface of the paint film.
2. Orange Peel
Phenomenon: The surface of the coating has an uneven texture similar to orange peel.
Cause: Improper spraying pressure, too fast solvent evaporation or too high substrate temperature.
Solution: Optimize spraying parameters, adjust solvent formula, and ensure that the substrate temperature is appropriate.
3. Pinholes/pinholes:
Defect manifestation: Holes as big as the tip of a sewing needle are scattered on the surface of the coating.
Surface particles/surface dust/pollution/industrial dust:
Defect manifestation: There are some dust particles on the surface of the paint film or polluted particles brought in during the construction process, which makes the paint film surface not smooth, and there are uneven layers and unevenly distributed raised particles.
4. Wake, Streaks:
Wake: There are thicker line-shaped "paint flows" at both ends or in the middle of the fan-shaped "spray" sprayed out by the nozzle.
Streaks: The above-mentioned "paint flows" have been sprayed on the surface of the coating and have been formed to present strip-shaped protrusions.
5. Cratering
Phenomenon: Local depressions appear on the surface of the coating, forming small pits.
Cause: Surface contamination (such as oil stains, silicone oil), poor wettability of the paint or mixing of incompatible substances.
Solution: Clean the substrate, optimize the paint formula, and avoid contact with the pollution source.
6. Corrosion/Rust:
Defect manifestation: Loose coating and discoloration stains on the paint surface, especially common at the edges and seams of the body. This may be due to corrosion such as rust and oxidation on the substrate surface, which leads to a decrease in coating adhesion.
7. Cracking
Phenomenon: Cracks appear on the coating after drying, or even peeling off.
Cause: The coating is too thick, the curing is too fast, or the substrate has poor elasticity.
Solution: Control the coating thickness, select flexible resin, and improve the adaptability of the substrate.
8. The Coating Is Not Dry Or Dries Slowly:
Defect manifestation: It is still not dry after exceeding the specified drying time, or it is still not cured after exceeding the specified curing time. The intuitive manifestation is that the surface of the paint film is soft or sticky, and it cannot be touched by hand, otherwise it will "leave a mark".
9. Discoloration
Phenomenon: The color of the coating changes over time, such as yellowing or fading.
Cause: UV irradiation, high temperature oxidation or poor weather resistance of the pigment.
Solution: Add UV absorbers, select weather-resistant pigments, and avoid high temperature environments.
10. Powdering/Yellowing:
Defect manifestation: Powdering on the surface of the coating or color change of the coating. This may be caused by direct ultraviolet rays, environmental factors (such as high air humidity), excessive temperature causing overreaction, or low yellowing resistance of the paint itself.
