Zinc phosphate coatings are composed of a maze of crystals on steel surfaces and act as absorptive media for organic materials. These coatings find extensive use in the automotive, appliance, and building trade industries.
A brief review is given of the processes occurring during the formation and growth of the crystals, their composition, and capillary or absorption properties. These studies led to the development of GMR Ferrotest which gives in one minute the corrosion resistance of zinc phosphate coatings and correlates well with conventional salt spray testing.
