Zinc phosphate coating is formed by crystallization on the surface by a chemical reaction. Zinc phosphating should be applied by spray or immersion, and it can be used for any phosphating application.
Spray coating on steel surfaces ranges in weight from 1–11 g/m2, and immersion coating from 1.6–43 g/m2. Zinc phosphate coating of 1.6–4.5 g/m2 is used for steel prior to painting, and coating of 1.6–43 g/m2 is used for zinc and zinc that was plated prior to painting. The type of phosphate coating and the coating weight of zinc phosphate coating for specific jobs should be approved by the company.