Case Studies


Case Studies:

Zinc Phosphate Pretreatment Coatings and Wastewater


The customer has two facilities; each has a zinc phosphate immersion line for pretreating fasteners with unique corrosion resistance requirements. In addition corrosion resistance, the zinc phosphate crystals provide a surface structure that allows specialty coatings to adhere during the Dip and Spin paint process.

The customer was struggling to produce zinc phosphate coating weights meeting their customers’ requirements. In addition, the zinc tanks generated excessive sludge, consumed unnecessary chemistry and required frequent dump/ recharge. The customer was also having difficulty treating their wastewater and had excessive zinc in their discharge water that was not meeting daily limitations. Their current chemical supplier did not have the technical expertise to solve their problems.

The DuBois Solution

DuBois partnered with the customer to improve quality and restore environmental compliance. Our local technical team and application specialists audited one of their facility’s zinc line and continuous wastewater treatment system. DuBois team identified several chemical, equipment and process improvement opportunities that they agreed to pursue. We then coordinated the zinc pretreatment line start-up with a sampling program that allowed us to evaluate coating weights and optimize wastewater treatment effectiveness. The results met customer quality expectations and environmental compliance. After proving our capabilities in Iowa, the customer converted to the DuBois program at their second location.

Results and Benefits

  • Less scrap and rework
  • Reduced chemical spend
  • No violations for zinc in wastewater
  • Ongoing technical support