What is the function of sealants and primers in corrosion prevention?

• A. Sealants prevent moisture ingress in joints; primers improve adhesion and provide corrosion-inhibiting protection.
• B. Sealants are decorative; primers only change color.
• C. Sealants corrosion ourselves; primers remove corrosion.
• D. They serve no protective function.

Answer: (A)

Sealants and primers work together to prevent corrosion by keeping moisture out and providing a protective coating. Sealants fill joints, seams, and fastener areas so water, salts, and other contaminants cannot penetrate into gaps where crevice corrosion or other moisture-driven attacks can start. Primers prepare the metal surface for the topcoat and add corrosion-inhibiting protection, often through pigments or inhibitors that slow or prevent rust and improve adhesion for the final finish. In aviation maintenance, primers commonly include active inhibitors (like zinc phosphate) that help shield the metal beneath the paint, while the sealant ensures a continuous moisture barrier at joints. This combination targets the two main corrosion pathways—moisture ingress and exposed metal surfaces—making it the best description of their protective function.