Zinc phosphate baths grow a layer of fine crystals, usually around 150 to 300 milligrams per square foot, that keys the powder and resists undercutting at scratches. The process needs a separate cleaner, a titanium-based conditioning rinse to seed fine crystals, tight temperature and acid control, and good rinsing. It is the standard choice for automotive, agricultural and appliance parts with demanding salt-spray specs.
Customer's spec is 1000 hours salt spray, so these go zinc phos, not the iron line.
Also heard as
- zinc phos
Related terms
Iron phosphate
A thin, amorphous phosphate conversion coating on steel, the economical standard for indoor and light outdoor parts.
Conversion coating
A thin layer formed by chemically reacting the metal surface, which improves adhesion and slows corrosion under powder.
Salt spray
An accelerated corrosion test that holds scribed coated panels in a warm salt fog for hundreds of hours.
Seal rinse
A final pretreatment rinse that fills pores in the conversion coating and boosts corrosion resistance.