Salt spray is an accelerated corrosion test. It does not reproduce a year in a seaside shop, and it is not a legal requirement by itself. Brands use it because a 48-hour cabinet run will catch a thin nickel plate or a skipped copper strike before 8,000 garments rust in transit.
The test people actually mean
Neutral salt spray (NSS) — ISO 9227 or ASTM B117 — is the apparel default. A 5% sodium chloride fog, pH roughly 6.5–7.2, cabinet about 35 °C. Parts hang so fog can settle. Inspectors look for:
- White rust: zinc corrosion products — the plate or the zinc substrate is going.
- Red rust: iron oxides — the steel core is exposed.
- Blistering or peel of the decorative layer.
Common apparel agreements: 24–48 h NSS for fashion trims; 96 h for better outerwear hardware. Outdoor and marine-adjacent goods may ask 168 h or more. Write the fail criterion (no red rust at 48 h, white rust allowed on cut edges, etc.). “Pass salt spray” with no hours is not a spec.
Harsher cabinets
AASS (acetic acid salt spray) and CASS (copper-accelerated acetic salt spray) are more aggressive. CASS is used on high-end decorative chrome in other industries. For a Zamak sew-on, NSS is usually the honest test. If a brand RSL names CASS, run CASS; do not “equivalent” it in an email.
Cyclic tests (salt, wet, dry) sit closer to real weathering. They are slower and belong on a technical outerwear program, not on a fashion brooch.
How to sample
Test the finished article, including antique wipe and lacquer. A bright nickel coupon is not your gunmetal pull. Masking, hanging holes and cut barrels rust first — agree whether cut edges count.
Salt spray does not replace EN 1811. A part can survive 96 h NSS and still release nickel. It does not replace lead/cadmium content either. Put all three on skin-contact metal when the destination is the EU or a strict US brand RSL.