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White residue after phosphating

2004

I am currently in the training division in an automotive company. My problem is this, after phosphating, a white residue forms on the layer of the metal. I had these analyzed and found out that it was composed of Phosphorus, Iron and Oxygen. We currently use the dipping process of phosphating in the company. What would you suggest would be the best process to eliminate the residue formation.

Phosphating process:

Derusting with Phosphoklene 135
Degreasing with Parklene 312
Pressurized water rinse
Coating with Phosphatane 811
Water rinse
Acidulated Acid Rinse

Richard Misa
automotive - Quezon City, Manila, Philippines

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2004

There can be several reasons for the phenomena:

1. Too much accelerator in the Phosphating bath
2. Acid Ratio too high .
3. Too heavy sedimentation in the bath

In reason one : Reduce quantity of the accelerator
In reason two: rise the free acid or reduce concentration
In reason three: Transfer the solution to another tank and clean the bottom of the bath from sediments

Yehuda Blau
YB Plating Engineering and Quality - Haifa Israel