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Is this a proper Hex Chromate solution?

I have info from a plater that this is how he mixes his Chromate tank, for passivation of Zinc - Nickel plating:

15.6 pounds sodium chloride
1.78 pounds sodium dichromate
5 gallons of water

pH optimum at 1.8

Does this make sense? Is there a reaction between the 2 salts that yields a highly acidic bath?

David Makinson
OEM - West Union, South Carolina, USA
August 25, 2011

November 4, 2011

Sir:

The chromate quench that we developed in Montreal consisted of sodium dichromate, acetic acid ⇦ this on eBay or Amazon [affil links] , and HCl to a pH between 4 and 4.5. This hex chrome solution was used on hot dip galvanized steel and passed the hydroquebec 40 hour salt spray test.

Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

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