What happens if a self-etching primer dries overnight?

When a self-etching primer dries overnight, it can lose its adhesion characteristics, which is crucial for its function as a primer. Self-etching primers are designed to create a mechanical bond with the substrate by chemically etching the surface. If they are allowed to dry for too long, the chemicals that provide this critical adhesion may cure beyond the optimal window, resulting in a compromised bond when it is time to apply the subsequent layers of paint or coatings.

The effectiveness of a primer is closely tied to its ability to properly adhere to the surface it is applied to. Therefore, applying topcoat paint over a self-etching primer that has improperly dried may lead to issues such as peeling or flaking, undermining the performance of the paint system. Proper timing after application is essential to ensure ideal adhesion properties are maintained.