摘要 |
More nearly consistent quality of the coatings formed by contacting a zinciferous surface with an aqueous liquid treatment composition comprising water, transition metal cations, and fluorometallate anions, and, optionally, acidity adjustment agents can be achieved by (I) measuring the pH value of and the concentrations of transition metal cations and of fluorometallate anions in the treatment composition as it is used, (II) removing a specified fraction of the treatment composition from contact with the remainder of the treatment composition, and (III) adding one or more suitable replenisher compositions to the treatment composition, in order to maintain the measured pH and concentration values within specified ranges.
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