Blasting for the Best Result

Powder coating lends itself well to social media: the dramatic before-and-after shots, the vibrant colors, the gloss and texture of the part after it’s been coated – it’s all very photogenic. We love to showcase our powder coating on Facebook and Instagram because we’re proud of the coating work we do, and because the visuals are so compelling.

But we’re called Kaser Blasting & Coatings for a reason.

Blasting could be considered a pretreatment of sorts, but it’s more about surface prep, particularly for metal substrates like steel, stainless steel, and aluminum. The best powder coating job in the world won’t adhere long if the part’s surface is not properly prepped. Whether it’s an old part with rust and chipped paint that needs to be removed, or a raw steel beam straight from the mill, we highly recommend blasting the part before powder coating it.

When raw steel arrives at Kaser, it has mill scale on it, like a crust. Sure, powder coating could adhere to the scale, but when the scale inevitably sheds off the beam, the color will go with it. Not only will this look bad, but it will expose the steel to the elements, resulting in rust. This is a huge problem, particularly for outdoor parts.

That’s why we start with blasting.

Our preferred media for blasting are steel grit (for steel parts), and crushed glass (for aluminum and stainless steel parts). The medium of choice gets forced through a large hose, powered by air at 120 psi. This destroys the mill scale and removes any pre-existing rust or paint, revealing the clean steel beneath.

Glass and steel each create a slightly different surface profile on the part – after steel blasting, for instance, the part will feel like fine-grain sandpaper to the touch, allowing the powder coating to properly “grip” the part when it is applied. Glass has a more gentle impact, making it ideal for softer, non-ferrous metals. Using the right medium for the part is critical: blasting an aluminum part with steel grit, for instance, can result in tiny flecks of steel being embedded in the substrate. Once powder coated, these flecks have a tendency to dislodge, damaging the coating, and the steel grit will create rusty pin-prick marks all over the part.

Attention to detail in the blasting process makes all the difference in the quality and longevity of the powder coating.

A freshly-blasted steel part is incredibly vulnerable to rust. With all of the mill scale gone, it can start rusting almost immediately – even the moisture from a hand can leave a mark within 24 hours. An iron phosphate coating can be applied to the steel part immediately after blasting, which delays rusting while cleaning any minor debris left over from the blasting process. A coating should be applied as soon as possible to prevent further rust.

Word to the wise: don’t skip blasting. No amount of pretreatment in the world will help powder coating adhere to a part that should have been blasted, and wasn’t. I estimate that an unblasted outdoor part will see powder coating failure within a year.

At Kaser, we prioritize quality and durability. That’s why we’re proud to offer blasting, and highly recommend it to customers with outdoor parts.

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