Chromating of zinc plating coatings / Black chromating
Pragokor Zn 51two component-based agent for the preparation of chromating baths
Two component-based agent PRAGOKOR Zn 51 is suitable for the preparation of chromating baths for the passivation of zinc coatings deposited from weak acid, alkaline non-cyanide and alkaline cyanide-based baths. The tone of the blackness of the chromate coating resulted, either dull or bright, will depend on the working conditions of the bath and quality of the zinc coating beneath. For the stable running of the chromating bath and formation of chromate coatings of superior quality, a brightening in about 0,5% solution of nitric acid in demineralised water, just before the chromating process, is necessary. The bath itself is convenient for both automatic as well as hand-operated plating lines.