Which component improves adhesion of the adhesive to the vehicle substrate?

• A. Adhesive
• B. Solvent
• C. Primer
• D. Masking tape

Answer: (C)

Primers condition the vehicle substrate to accept the adhesive. They provide a surface that is chemically compatible with the adhesive and have adhesion promoters that interact with both metal or painted surfaces and the polyurethane adhesive, improving bonding. By increasing surface energy and improving wetting, the primer helps the adhesive form a stronger, more uniform bond with the substrate, and it can seal micro-porosities and remove contaminants that would weaken adhesion. Without primer, the adhesive may not bond as effectively to painted or treated metal surfaces. The adhesive then bonds the glass to this prepared surface, while solvents assist with application and masking tape is used for protection, not adhesion.