Self-etching primer is a specialized type of primer that is intended for use on metal, aluminum, and fiberglass surfaces. It contains an acidic chemical that bonds, or etches, onto a metallic surface, creating a rougher surface for the topcoat to cling to. This etching process readies the metal for a topcoat and improves adhesion, durability, and color holdout of the topcoat. Self-etching primer is typically considered a high-build coating (HBC) and is formulated to only require one coat to complete the job.
To apply self-etching primer, the surface should be clean and smooth. Rust should be sanded off beforehand, and any damage that can be easily repaired should be fixed before starting the project. Self-etching primer is not suitable for repairing cracks in fiberglass.
Self-etching primer is commonly used in auto body repair and restoration. It is also used to prepare bare metal, aluminum, and fiberglass surfaces to promote maximum adhesion and smoothness of the topcoat. Etch primers are single pack metal primers formulated with a combination of resins to maximize adhesion to various metals.
