4 Layers of Automotive Refinish Paint

13th March 2024

Polyester Putty

Polyester putty, also known as polyester body filler or car body filler, is a type of material commonly used in the automotive industry for repairing dents, scratches, and other imperfections on the surface of vehicles during the refinishing process. It is a two-component product consisting of a polyester resin and a hardener (catalyst). When these components are mixed together, a chemical reaction occurs, causing the putty to harden and form a solid surface.

Polyester putty is often applied to areas of a car body that require smoothing or filling before painting. It is typically used on metal surfaces, although it can also be applied to fiberglass and some types of plastic surfaces. Polyester putty would normally cured within 20 minutes and can be sanded after 30 minutes.

Some common uses of polyester putty in car refinishing include:

  1. Filling dents and depressions: Polyester putty can be used to fill in small to moderate dents and depressions in the car body, restoring the surface to its original shape.
  2. Repairing scratches and imperfections: It can be used to repair scratches, gouges, and other imperfections in the car's paint or bodywork.
  3. Smoothing body surfaces: Polyester putty can be applied to uneven surfaces to create a smooth and level base for painting.


Primer serves as the foundational material on the surface of the car body steel plate, forming the first layer of the automotive paint coating system. Its primary function is to provide adhesion for the coating and prevent corrosion of the car body steel plate. Normally 2K system are used as primer——hydroxy acrylic resin and curing agent. The paint to curing agent ratio is 4:1.


Basecoat refers to the layer of paint applied to the vehicle after the primer and before the clearcoat. It is a colored paint layer that provides the actual color and appearance of the vehicle. Basecoat paint is usually applied in multiple coats to achieve the desired color depth and coverage.

  1. Metallic Paint (1K): Using acrylic resin with low hydroxyl value, no curing agent is added, mixed with CAB, while also adding aluminum silver paste, pearl powder, and other pigments with metallic effects.
  2. Color Paint (2K): Using hydroxyl acrylic resin with a hydroxyl value around 3.0, adding curing agent for drying. Paint to curing agent ratio is 2:1. It should be noted that after spraying this coating, it generally does not require additional polishing, so the coating itself has certain requirements for fullness and gloss.


The clear coat in car refinishing refers to a transparent layer of paint applied over the colored base coat during the automotive painting process. Its primary purpose is to provide protection to the underlying paint layers, enhance the appearance of the vehicle, and provide a glossy finish.

Generally, after spraying metallic paint, it is necessary to apply clear coat. Typically, a hydroxyl acrylic resin with a hydroxyl value around 3.0 is used along with a curing agent to form the film. For applications requiring high fullness, acrylic resin with a higher hydroxyl value is used, but it requires increasing the solid content of the curing agent. The paint to curing agent ratio is 2:1.

How long does paint hardener take to work?

The time it takes for paint hardener to work can vary depending on several factors, including the type and brand of hardener used, environmental conditions such as temperature and humidity, and the thickness of the paint layer. And it takes around 30 minutes for the hardener to get cured in most cases.