Phosphate Conversion Coating

Phosphate conversion (zinc- or iron-phosphate, with thin-film zirconium systems increasingly used as alternatives) is the chemical pretreatment that prepares steel body-in-white for e-coat. It creates a microcrystalline inorganic layer that improves adhesion and corrosion resistance. This is not a paint, not e-coat, and not a zinc-flake fastener coating. The closest library category is metal, because the conversion is formed on steel; the chemistry itself is inorganic. Applied by spray or dip in the pretreatment tunnel immediately before the e-coat bath. It is a process chemical, not a bulk mill product.