A Crash Course in Corrosion

As far as Kaser Blasting & Coatings is concerned, corrosion is Public Enemy #1. All of our services – blasting, pretreatment, coating, packaging – have the same end goal: keep corrosion at bay for as long as humanly possible.

In the grand scheme, it’s a losing battle. Corrosion is inevitable. But the more proactive you are about recognizing (and treating) the symptoms, the longer your metal parts will last.

Kaser sees three main types of metal parts:

  • Steel. When you think of quintessential orange rust, you’re thinking of steel. Steel is highly reactive to both moisture and oxygen. Uncoated parts start rusting quickly, particularly in humid environments. Rust will eventually eat through the substrate, leaving it pitted and full of holes. Given enough time, steel parts will disappear entirely.

 

  • Aluminum. While it’s true that aluminum doesn’t technically rust, left untreated, it will still oxidize and corrode. Corroded aluminum typically looks white and chalky, and occasionally will develop black spots. This happens fastest when aluminum parts are stacked up with water trapped between them. However, raw aluminum exposed to the outdoors will start to develop a chalky, frosted look after a while. That corrosion is just as detrimental as rust is to steel – over time (much longer than steel), corrosion will eventually eat the aluminum away.

 

  • Stainless steel. Most people think that stainless can neither corrode nor rust. That’s true…IF the stainless steel is high quality. If there’s no iron in your stainless (meaning that magnets won’t stick to it), your stainless steel likely won’t corrode. Less-expensive stainless steel tends to be less pure – it has more iron in it, making it more vulnerable to corrosion. While it won’t rust nearly as fast as steel would, stainless with a higher iron content probably should not go completely uncoated for too long.

So what do we do about all of this?

The simplest way to remove corrosion is to blast it off (steel grit on steel, crushed glass on aluminum and stainless). Caught early enough, corrosion flakes off like a surface crust, revealing a smooth, new-looking substrate underneath. If a steel part has been rusting for years, however, you may be unpleasantly surprised by how deep the rust goes, and how little substrate is left after the rust is blasted off. Don’t wait too long.

Interestingly, the more corroded the part was before blasting, the faster it will corrode again after blasting. This is particularly true in Nebraska, where the weather is humid most days – if we blast a part that has invasive corrosion in the morning, we’re careful to pretreat it (and, ideally, powder coat it) that very afternoon. Left exposed overnight, it will have started to rust again as soon as the next morning.

There is no permanent solution for corrosion. The best we can do is to ward it off for as long as possible, using every tool in our arsenal. The more you invest in their upkeep, the longer your metal parts will last.

Previous

Next

Submit a Comment

Your email address will not be published. Required fields are marked *

Share This