Pretreatment for Powder Coating

Question:

What method of pretreatment must I use to get a good bond with super durable polyester powder on stainless steel screw heads? We would like to color match the screw heads to the finish on our aluminum windows when the fasteners are exposed. We have tried using the immersion chromate conversion, which is used for coating the aluminum extrusions for windows, but the finish leaves the fastener head when driven. D. S.

Answer:

The chemical you seek is called Silane. Chromate will not help on stainless steel.