Quick Answer
A salt spray test exposes metal bag hardware to a heated salt fog inside a closed chamber and measures how many hours pass before corrosion appears — the standard lab proxy for how a finish survives sweat, humidity and coastal air. For daily-use bags, buyers typically specify 24 hours as a minimum, 48 hours for mid-market programs and 72 hours or more for premium or coastal-market hardware, always tested on the final base-metal-plus-finish combination. Maya Metal runs salt spray testing as part of its quality assurance process and reports hours to failure on every custom hardware program.
What Does a Salt Spray Test Actually Measure?
The common method is the neutral salt spray (NSS) test: parts hang in a chamber at 35 °C while a 5% sodium chloride solution is atomized into a fine fog that settles continuously on the surfaces. Inspectors pull the parts at set intervals and record when the first white corrosion products, red rust, blistering or coating peel appear. The result is a single number — hours to first corrosion — plus notes on where failure started.
Two things the test does not tell you: it is not a real-time simulation (48 chamber hours does not equal 48 days of use), and it says nothing about abrasion, which is how most bag finishes actually die. Salt spray ranks corrosion resistance between candidate finishes; it does not certify a service life. Treat it as a comparative gate, not a guarantee.
How Many Hours Should You Specify by Market Tier?
- 24 hours — the functional floor for fashion-price bags sold inland; catches porous plating and missing undercoats but little else
- 48 hours — the mainstream mid-market specification; a sound plated or PVD finish on brass or stainless steel should pass comfortably
- 72–96 hours — premium programs, humid and coastal markets, and hardware that touches skin or sweaty hands regularly, such as handles and clasps
- 120 hours and above — typically achievable only with PVD on 304 stainless steel or heavy multi-layer plating; specify only when the market genuinely demands it, because it constrains finish choices and raises cost
The right number is the one matched to your warranty exposure: set the hours where a field failure would cost you more than the finish upgrade.
Why Do Base Metal and Finish Change the Result So Much?
Salt spray performance is a property of the whole stack — base metal, undercoat, top layer — never of the finish name alone:
- 304 stainless steel — resists red rust even when the decorative film is scratched through; the strongest base for high-hour specifications
- Solid brass — will not red-rust, but exposed brass darkens and pits; a good nickel or copper undercoat under the top finish is what carries the hour rating
- Zinc alloy — the weakest base: once the coating pores through, the substrate corrodes fast and blisters the finish from beneath; keep zinc parts to modest hour targets
- PVD top films — chemically inert and dense, they outperform same-color electroplated layers at equal thickness, which is why high-hour specs usually end up as PVD on stainless
Process choice matters as much as material — see our comparison of PVD coating vs. electroplating for how the two systems differ before testing even begins.
What Should a Salt Spray Specification Include?
“48 hours salt spray” on a purchase order is not testable on its own. A complete specification states:
- Test method — neutral salt spray per ASTM B117 or ISO 9227, so both labs run the same chamber conditions
- Hours and acceptance criteria — e.g. “no red rust, blistering or peeling at 48 h on functional surfaces”, with a defined inspection area
- Sample state — test the final production finish on the actual base metal, not a lab coupon of a different substrate
- Part coverage — which components are tested (locks, rings, chains, logo plates), since one bag can carry three finish systems
- Companion tests — artificial sweat and abrasion cycles for touch points, because salt fog alone misses how clasps and pullers wear in hands
- Batch policy — test per finish batch or against a retained master sample, so the rating survives reorders
Corrosion Test Buyer Checklist
Before approving bag hardware finishes for production, check:
- Test reports reference ASTM B117 or ISO 9227 and name the base metal and full finish stack tested
- Acceptance criteria define failure (red rust vs. white corrosion vs. blistering) and the inspected surfaces, including recesses and hinge areas
- Tested samples came from the production finish batch, not a separately prepared showroom set
- Hour ratings match the market tier — and the same rating applies to every component on the bag, not just the lock
- Artificial sweat results exist for skin-contact parts, and abrasion cycle data for moving parts
- Retained master samples are agreed for color and finish comparison on reorders
Send us your target markets and component list — our team will recommend finish stacks with proven hour ratings, run salt spray and sweat tests on your actual parts and include the reports with your approval samples.
