What should you do after identifying the substrate of the vehicle?

After identifying the substrate of the vehicle, the next step is to select the appropriate undercoat for application. This step is crucial because different substrates, such as metal, plastic, or fiberglass, require specific types of undercoats to ensure proper adhesion and performance of the subsequent layers.

Selecting the right undercoat is important for compatibility with the substrate, the finish coat, and any topcoat that will be applied afterward. For instance, metal substrates might need a corrosion-resistant primer, whereas plastic substrates may require a primer that can adhere well to non-porous surfaces.

Choosing the first primer that looks suitable lacks the careful consideration needed for the specific requirements of the substrate, which can lead to poor adhesion, peeling, or other failures down the line. Similarly, beginning to sand the surface immediately disregards the importance of understanding the substrate, which could affect how the surface should be prepared. Applying a finish coat to test adhesion is also premature, as it skips vital preparation steps that ensure a quality and durable final result. Thus, selecting the appropriate undercoat aligns with best practices in painting and refinishing processes.