Basecoat
Automotive paint is paint used on automobiles for both protection and decoration purposes. The paint layers total to around 100 µm.
Modern automobile paint is applied in several layers, with a total thickness of around 100 µm(0.1mm).
In the early days of the automobile industry, paint was applied manually and dried for weeks at room temperature. As mass production of cars started, paint was dried in ovens. Nowadays, paint is usually applied by robotic arms and dried in just a few hours.
Until several decades ago lead, chromium and other heavy metals were used in automotive paint. Environmental laws have prohibited this, which has resulted in a move to water-based paints. Up to 85% of lacquer paint can evaporate into the air, polluting the atmosphere. Enamel paint is better for the environment in that regard, and has become the most widely used paint nowadays.
High-pressure water spray jets are directed to the body. Without proper pretreatment, premature failure of the finish system can almost be guaranteed.
A phosphate coat is necessary to protect the body against corrosion effects and prepares the surface for the E-Coat.
The body is dipped into the Electro-Coat Paint Operation (ELPO/E-Coat), then a high voltage is applied. The body works as a cathode and the paint as an anode sticking on the body surface. It is an eco-friendly painting process. In E-Coat, also called CED paint, utilisation is approximately 99.9% and has great SST life compared to other painting processes.
The primer is the first coat to be applied. The main functions of the primer are to act as a leveler and protector, and to make the base coat easier to apply to the component to which it is applied. The primer serves several purposes. It serves as a leveler, which is important since the cab often has marks and other forms of surface defect after being manufactured in the body shop. A smoother surface is created by leveling out these defects and therefore a better final product. It serves as a protector, the primer will protect from corrosion, heat differences, bumps, stone-chips, UV-light, etc. It also improves ease of application by making it easier for paints to stick to the surface, a more varied range of paints can be used.
The base coat is applied after the primer coat. This coat contains the visual properties of color and effects, and is usually the one referred to as the paint. Base coat used in automotive applications is commonly divided into three categories: solid, metallic, and pearlescent pigments.
...
Wikipedia