If you are qualifying a plating supplier, the salt spray number is one of the few things in the quotation you can actually verify. It is worth understanding what it does and does not tell you.
What the test is
A salt solution is atomized inside a sealed chamber, creating a corrosive fog. Test pieces are exposed continuously. The most common variant is the neutral salt spray test (NSS), run at a controlled temperature and concentration. It is an accelerated test: it compresses months of real-world exposure into days.
What "72 hours" means
It means the part was exposed to the salt fog continuously for 72 hours and then evaluated against an agreed acceptance criterion, usually the appearance of red rust or a defined level of corrosion products. Longer duration with fewer defects means better corrosion resistance. Our parts meet a 72-hour NSS standard.
The procedure
- Clean the test pieces and record their initial condition
- Load the chamber and set the parameters
- Run continuous fog for the specified duration
- Remove, rinse, and evaluate against the acceptance criterion
What it does not tell you
Salt spray is an accelerated, standardized test. It is excellent for comparing two suppliers under identical conditions. It is a poor predictor of exactly how long your part will last on a customer's kitchen counter, because that depends on the real environment. Treat it as a comparative benchmark, not a warranty.
How to write it into a spec
State the test method, the duration, the acceptance criterion, and who pays for the testing. Vague language here becomes an argument later, after the parts have shipped. Say "72 hours NSS, no red rust on the significant surface" rather than "good corrosion resistance."
FAQ
Is longer always better?
Within reason, yes, but it costs money. Match the requirement to the service environment.
Can you run salt spray testing?
Yes, on request. Our parts meet a 72-hour standard.
What affects the result?
Coating type and thickness, pretreatment quality, and whether there is a nickel undercoat. See technology and certification. Request a quote.