What is the function of undercoat in automotive painting?

The primary function of the undercoat in automotive painting is to bind bare metal and prevent rust. When a vehicle undergoes collision repair or refinishing, the undercoat serves as a protective barrier between the metal surface and the environment. This is crucial because exposure to moisture and air can lead to corrosion, which not only compromises the integrity of the vehicle but can also cause ugliness and further damage over time.

The undercoat aids in adhesion, ensuring that subsequent layers of paint adhere effectively without peeling or chipping. By preventing rust formation, it extends the durability of the paint job and contributes to the overall longevity of the vehicle's bodywork. Therefore, the use of an undercoat is an essential step in the painting process to protect the bare metal surfaces and maintain the vehicle's quality over time.