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Recommended exterior finishes for yellow zinc

 

I need a recommendation for a primer and topcoat for mild steel parts which are pre-treated with yellow zinc. I was asked this question, and I didn't have a good answer, and was hoping for some suggestions from your staff or readers.

The coating process needs to be simple, such as a dip process using an air dry, one-pack primer and topcoat.

The finished parts will exposed to exterior weathering in the northeast region of the USA. They will not be subject to any abrasion or wear, strictly long term exterior exposure. Sufficient adhesion to the yellow zinc is a prime issue.

John E. Blasko
- Racine, Wisconsin

Hi John,

Lets start from the beginning , I am assuming that by Yellow Zinc you mean Zinc plating with a yellow chromate conversion coating . If so here is what you should be asking for Zinc plating to a minimum thickness of 12.5 microns ( 0.5 thou ) plus a yellow / iridescent chromate conversion coating . This must then rest for at least 24 hours but preferably 48 hours before spray painting with any good Zinc rich primer, preferably 2 coats minimum applied according to the manufacturers instructions then choose a compatible low temperature cured baked enamel finish with as many coats as you like , but I have used 2 and the doors of the Barbecue so treated are still as good as new after 15 years outside exposure to a city environment .

Best of luck,

John Tenison - Woods
- Victoria Australia