What is the importance of surface moisture in the bonding area before curing?

• A. Moisture accelerates curing and strengthens the bond.
• B. Moisture has no effect on bonding.
• C. Moisture can interfere with adhesion, cause air voids, and weaken the bond.
• D. Moisture only affects the appearance of the cured joint.

Answer: (C)

Surface preparation is critical for a strong bond because the adhesive must wet and contact the bonding surface uniformly. When moisture sits on the bonding area, it lowers surface energy and prevents the adhesive from spreading evenly, so wetting is poor and the bond can start with weak contact. As the adhesive cures, trapped moisture can form tiny air voids within the bond line, creating weak points that compromise strength and durability. In short, surface moisture can hinder adhesion and lead to a weaker, less reliable bond. That’s why the bonding area should be clean and dry before application, following the manufacturer’s guidelines for any cleaners or primers.