Frequently Asked Questions About Pretreatments for Powder Coating

March 1, 2019 3:09 pm Published by Leave your thoughts

Powder coating is one of the best methods available for protecting parts made out of various material, most commonly metal. Here are some of the most frequently asked questions we receive about the pretreatment process for powder coating as experts in metal fabrication in Umatilla County, OR.

Q: How do the pretreatment and wash systems differ for powder coatings versus liquid paints?

Powder coatings are designed to provide better performance than liquid paints when applied to a part that has been properly pretreated. Therefore, it’s more important with powder coating that you ensure the washing has been performed well before you start the powder coating process, as powder coating is not nearly as forgiving as solvent-borne paints with regard to any organic soils and debris left on the piece that is to be coated. Iron phosphate is the most commonly used pretreatment for powder coatings, but zinc phosphate is also sufficient.

Q: What’s the best cleaner to use for powder coating?

This really depends on a variety of factors, including the type of base metal of the piece being coated, the soil that’s being removed from the metal, the temperature of the bath, contact time and various environmental considerations. A supplier can provide you with more information about effective cleaners to use depending on your needs.

Q: How can I be sure my parts have been sufficiently cleaned?

There are many different types of tests you can use to determine if your parts are clean enough to be powder coated. One common test is the “water break free” test. Perform a visual observation to see whether water will fully sheet over the clean part, or if it draws away from some parts of the surface, similar to how water slides off a waxed car. You might also try wiping the part with a white cloth to see if any dirt or residue shows up on the cloth, perform some alcohol drop tests or even participate in some more sophisticated testing in a laboratory setting. The testing method you use depends on your pretreatment methods and your own personal preferences.

Q: How do I choose the right pretreatment for my particular application?

The most frequently used pretreatment is iron phosphate, because it is highly versatile and can be used with just about any type of substrate. If you’re working on a higher-end application, zinc phosphate might provide you with even better results, though this process is much more costly and can produce some sludge and waste that isn’t exactly environmentally friendly. The process can also take longer when compared to iron phosphate washing.

Q: Is there anything in particular that I should know about pretreatment waste?

The main concerns you’ll have are oil and grease, pH and metals. There can be some sludge buildup inside the cleaner—consult your supplier to learn more about potential for waste and how you should handle it.

For more information, contact NW Metal Fabricators Inc. today about metal fabrication in Umatilla County, OR. We look forward to assisting you!

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