Rinsing after Phosphating

Parts must be rinsed after being phosphated to remove active chemicals from the phosphating solution that remains on the surface of coated parts. Any chemicals not removed may cause corrosion of parts or blistering of a subsequent paint film. Any phosphating chemicals carried over into the chromic acid rinse may contaminate the solution used as a rinse. Rinsing after phosphating never should be hot. The temperature should range from 20 to 50 °C (70 to 120 °F), preferably maintained on the low side. A rinse that is too warm may set the residual chemicals and cause them to adhere to phosphate crystals, resulting in a rough coating, whitish appearance of coating, and lower corrosion resistance. Usually, only one rinse is required. If the water supply is so high in mineral content that a residue remains on the parts after rinsing, a rinse in deionized water may be required.

0 0

Post a comment