Why does the paint coating sag after painting the car?

Why does the paint coating sag after painting the car?

During the painting process or the drying process of the paint film, due to the expansion of the paint surface, some areas will form bulges, and the bulges have different shapes. The reasons is as below:

1. The substrate is not clean. There are still dirty things such as oil, dust or wax on the surface of the substrate, which will cause the newly sprayed paint to fail to adhere under the influence of the interlayer effect.

2. Improper use of car paint thinner. Use highly volatile paint thinners in automotive paint, when the paint is dry, the surface of the paint film is already dry, and the solvent inside cannot volatilize normally, which seals the volatilization in the internal paint layer, causing the topcoat layer to detach. Make the paint bulge.

3. The spraying interval between paint layers is too short, the previous layer does not have sufficient drying time, and the next layer is sprayed immediately, easily causing the water in the wet paint surface to erode the primer or topcoat and make it soft.

4. The viscosity of the paint is too high, or the proportion of thinner paint is not properly mixed, which may also cause swelling.

Therefore, it is necessary to pay attention to cleaning the substrate, use the thinner recommended by the manufacturer, and extend the interval between spraying auto paint. The coating should be thin and uniform every time. If swelling has occurred, it is advisable to sand the defective areas, taking care not to wear through, and then re-spray.