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Iron Phosphate Coating

We manufacture steel and aluminum panels for testing paints and coatings. We also supply panels pre-treated with Iron Phosphate. The chemical used is Bonderite 1000, with a chrome seal.

A customer has raised concerns that the performance of the phosphate coating deteriorates over time (if stored for long periods prior to painting). They also claim that baking the phosphate coating prior to painting improves performance.

s there any reason baking priot to painting would improve performance and what is the reason for the deterioration in performance over time of an unpainted phosphate coating?

Patrick Patton
Westlake, Ohio

Hi Patrick,

It is true. Phosphate coatings have high specific surface area. Phosphate coatings tend to absorb water and other organic compounds from atmospheric environments in terms of capillary effect with time, particularly in the hummy areas and industrial fields. Both water and other organic contaminants are harmful to paint adhesion. Baking at an adequate temperature is able to eliminate water and the organic contaminants absorbed over time.

Regards,

Ling Hao
- Grand Rapids, Michigan

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