From Fastener Technology International, October 2012
In the early days of my career, when I was occasionally working on new part approvals, and then later when I was overseeing such activity, a common and frustrating event was to discover that parts submitted to the customer for approval did not pass their salt spray test. This was particularly confounding because those same parts would have passed our internal testing and often that of our plating vendor. I would quickly come to learn that this is a common industry problem and one likely experienced by every fastener manufacturer or distributor at one time or another.
To compound this frustration, I learned that although the experts have long debated the pluses and minuses of this test, regardless of which side they fall, they universally agree that this test may not provide similar results between test cabinets (even though all process parameters have been followed) and that the mechanism of failure is so radically different from real world application, that there is no known or accepted correlation between salt spray hours passed and actual performance in real-world service.
One might logically ask then, what the value of this test is, what is really happening amid that salt fog and why other test methods haven’t replaced it. The following is an attempt to understand more about the process and tackle these and other questions regarding this universal and deep-rooted test method in qualifying fastener quality and ability to withstand service corrosion conditions.