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Pre Treatment Powder Coating Issues

I'm new at powder coating and have a question involving my pre treatment process. We are currently using a two- stage method: Hurrisafe wash (degreaser), tap water rinse, iron phosphate/ sealer rinse, tap water rinse. The steel parts are hung to dry and placed in front of warm, forced air. The problem is we are seeing rust, flash rusting, and chemical residue left over. Do we need a neutralizer? And is sodium hydroxide a neutralizer?

Thanks for any help,

Jason Waldorf
powder coating - Clinton, Iowa, USA
2004

There are many alternative to iron phosphates pretreatments which will prevent your parts from flash rusting. A good pretreatment should inhibit corrosion and enhance paint adhesion with out the need of additional sealers and neutralizers. Another thing you can try is to increase the quality of your rinse water.

Jonathan Flicher
- Chicago, Illinois
2004

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Good day,

The parts should be going from stage to stage as fast a possible so that they don't dry out in between. You shouldn't be rinsing again after the seal rinse, and the faster you get them dry after the seal rinse, the better.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2004

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After rereading your question, I thought I would add another comment. The residue that you are seeing could be from the water, not the chemical. You might want to check the concentration of the chemical that you are spraying onto the parts to make sure that it's in line(within reason, decrease the concentration until the residue is no longer evident). Either way, the only way that I would add another step after the phosphate/seal rinse would be a D.I. mist.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
2004