Automotive Body Painting: Processes and Techniques

Fabrication Painting: Cleaning and Degreasing

The areas of the car body tend to accumulate fat and dust, which must be removed before painting to ensure the product's adherence to the wing area.

Phosphating

This is a surface treatment that converts the metal. The metal is treated with a layer of microcrystalline zinc phosphate. The bodywork is immersed in a bath of composite with phosphoric acid, zinc phosphate additives, and accelerators. This provides a more uniform coating and better penetration into the hollow parts than spraying.

Responsibilities

After the phosphating process, the surface is washed with a passivating aqueous solution, which improves grip and anticorrosion protection.

Drying

This is performed with hot air to harden the layers formed on the car body.

Cataphoresis

This is another anticorrosion treatment. A layer is created through electroplating, where the product is deposited on the bodywork by electrical current. The bodywork is introduced into a cataphoretic paint bath, and a layer is deposited that does not conduct electric current.

Other Protection Methods

Hermetic sealing is used to prevent water filtering, and sound-absorbing panels are also used to decrease vibration. Protection with anti-gravel is also applied.

Priming

Before applying the finish, rigorous sanding is done to eliminate small surface defects. After this, the primer is applied to achieve a uniform surface that ensures the adhesion of the finish paints. The primer is atomized into fine droplets that are attracted to the car body through magnetic fields, connecting the car body to a negative current. After drying, it is sanded to remove small defects.

Applying the Finish

The finish paint is usually applied using electrostatic systems. In some cases, the process is completed with manual systems. There are two types of finishes: monolayer and bilayer. Monolayer applies only one product that gives color and brightness, while the bilayer uses two products: color and glaze, which gives shine. The thickness is 45 microns in monolayers and 15 in color and 40 in the glaze for bilayers.