The zinc phosphate conversion coating process used today converts the metal surface into a non-metallic, polycrystalline coating containing iron, manganese, nickel, and zinc phosphates. Since the zinc phosphate pretreatment process converts the metal surface, the coating provides an excellent base for paint adhesion. As zinc phosphate conversion coatings incorporate additional metal ions into the coating to increase the alkaline resistance, it makes an excellent paint base offering superior adhesion and durability.
The zinc phosphate pretreatment process is applied by either spray or immersion applications depending on the industry and can be used on a wide variety of substrates including steel, hot-dipped and electrogalvanized, zinc-nickel alloy, and aluminum. Each of these processes incorporates three to four chemical stages.
Once the zinc phosphate conversion coating has been successfully applied to the metal surface, the coating provides an excellent base for powder paint, electrocoat, and liquid paint, water or solvent based. The final zinc phosphate coating and paint application creates a finished surface with excellent adhesion and corrosion resistance.