Tri cationic phosphating: smart fixes for poor bath performance

Summary for tri cationic phosphating Discussion

Tri cationic phosphating is the focus of this thread, where Hamed Khakzad amirkabir asks why his Henkel bath gives a smooth, dense coating at first but performs poorly after two immersion cycles, with high sludge, hard water, and questions about improving salt spray resistance and bath conditions. A. Wagstaff says the process sequence is not normal because an acid degreasing tank should not precede zinc phosphating; he recommends alkali cleaning/degreasing, rinses, conditioning, and then the tricationic phosphate stage, and advises getting more guidance from Henkel. Rahul Deshpande adds that the bath should be controlled by maintaining the total acid to free acid ratio and accelerator concentration, and suggests taking the derusting acid bath offline for better phosphate bath maintenance. The thread does not give a single formula or additive recommendation, but emphasizes proper pretreatment and bath control.