Which term is a preparatory material designed to improve adhesion between adhesive and certain substrates, and may inhibit corrosion depending on composition and paint thickness?

• A. Prep
• B. Sealer
• C. Sealant
• D. Primer

Answer: (D)

Primers are coatings applied to a substrate before bonding with an adhesive to create a surface the adhesive can cling to more effectively. They tune surface energy, fill micro-porosity, and improve chemical compatibility, which strengthens the bond between the adhesive and the substrate. Many primers also include corrosion-inhibiting additives, so they can help prevent rust, with the level of protection depending on the specific chemistry and the thickness of the overlying paint. Other terms describe preparation steps or sealing functions that don’t primarily aim to boost adhesive adhesion or provide corrosion protection, so the option that best fits the description is primer.