PROCESS TO CONTROL A TREATMENT SOLUTION, ZINC PHOSPHATE BASE OR ZINC PHOSPHATE / NICKEL, FOR CONVERSION COATING

摘要

A process for controlling the zinc or zinc and nickel content of a zinc phosphate conversion coating solution employs the addition of EDTA and titration with calcium ion using a calcium ion electrode. Preferably to a second sample is added EDTA and a thioglycolate and the same titration conducted to obtain the concentration of nickel ion for direct control purposes.