How do sealers differ from primer-surfacers?

Sealers function primarily to enhance the adhesion of subsequent layers of paint and coatings while providing a barrier to prevent moisture and contaminants from affecting the substrate. Unlike primer-surfacers, which are designed to fill imperfections and provide a smooth surface that can be sanded, sealers do not offer significant filling characteristics and are typically left unsanded. This characteristic allows them to effectively bind to the surface and create a foundation for the topcoat without altering the surface texture.

The distinction between sealers and primer-surfacers is important, as primer-surfacers are usually formulated to fill scratches and other surface defects and are commonly sanded to prepare for the final paint layer. In contrast, sealers focus primarily on surface penetration and adhesion rather than filling capability.