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Cleaning or darkening the galvanized steel prior to powder coating

"Phosphating of Metals"
by Werner Rausch
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"Handbook of Hot Dip Galvanization"
by Maass & Peissker
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I would like to paint some galvanized steel with powder coatings. But I do not know how to prevent the powder coating to be peeled afterwards. Can anybody help me to make a chemical procedure before painting the galvanized surfaces.

Thanks,

Zlen Petmezciler
- ISTANBUL, Turkey

Before applying powder coating, make sure that the surface has been properly prepared: i.e., remove all superficial impurities from the surface, etch the surface, chromate-coat the surface, make sure that the surface is bone-dry, and apply the powder coating, heating it to the temperature and duration recommended by the powder manufacturer.

Pre-treatment process effective at around 25 to 40 °C are available.

S. MEENAKSHISUNDARAM
- CHENNAI, TAMIL NADU, INDIA

June 1, 2009

Hi, Zlen. While chromate conversion coating of the galvanized surface can be done, I believe that the best way to prepare galvanizing for powder coating is to zinc phosphatize it. If you patiently search the site for "galvanize powder phosphate" you will find a number of helpful threads. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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