Term: etch primer

Etch primer is a type of primer specifically formulated to promote adhesion between bare metal surfaces and subsequent layers of paint or coatings. It contains acidic components—typically phosphoric acid—that chemically react with the metal surface, creating a micro-etched profile. This etching process improves paint adhesion and also provides a degree of corrosion resistance.

Etch primers are commonly used in automotive, industrial, and architectural painting applications, especially on non-ferrous metals like aluminium, galvanized steel, and stainless steel. In Australia, etch primers are often used in compliance with AS/NZS standards for surface preparation and coating systems.

Key features of etch primer:

• Excellent adhesion to bare metal
• Provides corrosion resistance
• Often used as the first coat in a multi-layer paint system
• Typically applied in thin coats
• Requires proper surface preparation (clean, dry, and free of contaminants)

Note: Etch primers are not suitable for use over existing paint or filler and are generally not sandable. They are usually followed by a high-build primer or undercoat before topcoating.