“Please advise on recommendations for pre-treatment through to powder coating of material supplied as galvanized. The intention would be to hand supplied material from supplier with the process performing all functions such that finished powder coated material would be removed from the line, packed and shipped. Thanks.”
“The first step is to use a paintable grade of galvanized steel (i.e. galvanneal, paintgrip, or electroplated galvanized). Hot or cold dipped galvanized steel will cause problems with out gassing and powder adhesion.
The preferred pretreatment for galvanized steel is zinc phosphate. This will provide prolonged salt spray resistance and excellent adhesion. A chrome sealer rinse would also be nice, if you can use that material in your country. The pretreatment system typically has seven or more stages to apply these chemicals, depending upon the soil load on the raw product. You should contact a competent pretreatment chemical supplier for help in selecting the right chemistries.
The product should be perfectly dry before powder coating. A dry-off oven suits this task well. The part should be cool to touch at time of powder coating. Coat and cure the product as normal with your equipment.”