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Chromate passivation solution is stripping the cadmium plating

We have recently made up a solution of Chromate Passivation for our cadmium plated parts.
This sol. consists of Sodium Dichromate 165 lbs/100 gal and sulfuric Acid 1gal/100gal.however when we went to use the new sol. we found it was stripping the cad. back to base metal.
The analysis shows Chromic Acid 96.7 g/l and pH 1.09.
The recommended values are 37-76 g/l and pH 0.8-1.1.
Can you suggest why it is stripping the cad.and how we might rectify it.

Frank Dunleavy
Aerospace - Dublin, Ireland, USA
October 28, 2008

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