Fun Facts About Substrates Other Than Steel

I could talk about steel for days, and I have. That’s partially because Kaser blasts & coats a lot of steel, but it’s also because steel lends itself well to social media content: it’s quick and rewarding to blast, it turns interesting colors after pretreatment, and that bright orange rust makes for good before and after shots.

But Kaser also encounters a number of other substrates, which present their own unique challenges during the finishing process. Here are a few things that customers should know about their non-steel parts.

Aluminum corrodes.

Aluminum may corrode more slowly than steel, and it certainly corrodes less visibly – but the absence of that telltale orange doesn’t mean you’re safe. Aluminum corrosion shows up as “white rust,” a powdery, flaky residue that looks a bit like mold from afar. It must be dealt with before the part is coated. Light corrosion can be removed chemically in the wash bay; if the part has been left to corrode for too long, it will require blasting (and, occasionally, sanding) before it’s pretreated.

Cast iron outgasses.

Galvanized and cast iron parts behave very similarly in the powder coating oven: they outgas. Try as we might (through blasting, pretreatment, and even heating parts up before they’re coated), these substrates are highly likely to release gasses during the curing process, causing pinholes in the powder coating. Can they still be powder coated? Yes. But I strongly recommend that you select a textured powder to help hide any pinholes.

Stainless steel is not so stainless (lately).

Has anyone else noticed that stainless steel is more ferrous than it used to be? It’s no longer uncommon to see stainless steel parts coming in rusty. In one extreme case, some stainless steel parts that we coated started to rust along sharp edges only weeks after installation. This noticeable change in stainless steel quality has caused me to rethink some of Kaser’s pretreatment processes. Customers, take note: don’t assume that your parts are immune to corrosion just because they’re stainless.

Finishing processes aren’t one-size-fits-all. Knowing how a substrate behaves is the first step to blasting & coating it effectively.



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