A salt spray test result needs its test conditions and acceptance criteria. A figure such as “500 hours” alone cannot establish product superiority or predict service life.
Start by checking whether the conditions match
A purchasing requirement of “SST ≥500 hours” and a supplier statement of “passed 500 hours” may refer to different criteria. A result evaluated for white rust is not interchangeable with one evaluated for red rust.
| Item | Information to obtain |
|---|---|
| Test method | Standard and edition, test type, temperature, solution conditions and duration |
| Specimen and treatment | Substrate, geometry, pretreatment, coating system, thickness and drying or curing conditions |
| Acceptance criteria | White or red rust, permitted area or rating, and assessment time |
| Exposed areas | Edge sealing, presence of a scribe, and areas excluded from assessment |
| Result records | Specimen photos and report; distinguish condition at test completion from the actual time corrosion was first observed |
If details are missing, obtain the complete report or evaluate the candidates under matching conditions before comparing them.
A practical example: ELPANG Upgrade 300 at different thicknesses
KEMP’s published ELPANG table lists the following results for Upgrade 300. These are reported table values, not a guarantee that every component and process will achieve the same result.
| Coating thickness | White rust | Red rust |
|---|---|---|
| 3–5 µm | 60 hours | 300 hours |
| 5–6 µm | 72 hours | 400 hours |
| 8–10 µm | 96 hours | 500 hours |
“Upgrade 300” therefore does not mean a universal 300-hour result. Nor does a 500-hour red-rust result establish 500 hours without white rust. Review the original ELPANG performance table and the test report for substrate, pretreatment and specimen details, then evaluate representative parts.
How should you read the Innozinc SST ranges?
KEMP product information lists SST ranges of 720–1,000 hours for Innozinc and 1,500–2,000 hours for Innozinc-h. These ranges are not a service-life warranty for a particular part. Confirm the substrate, process, thickness and white-rust or red-rust criteria for the specification being considered.
The Innozinc-h performance evidence lists SST and CCT separately. Do not convert SST hours into CCT cycles or rank them as if they were the same measurement. Start with the test required by the customer’s specification.
Can test hours be converted into years in service?
There is no fixed conversion. ASTM B117 describes a controlled salt spray test environment. Its public explanation identifies limitations in predicting natural-environment performance from salt spray results alone.
Actual exposure varies with wet and dry periods, salt, temperature, abrasion, assembly, damage and maintenance. A service-life assessment needs additional evidence, including the intended environment and relevant field history. Avoid setting a purchasing requirement on the assumption that “1,000 SST hours” equals a fixed number of outdoor years.
What to prepare for a sample evaluation
- Component and process: substrate, drawing, geometry, dimensional tolerance, current treatment and thickness.
- Exposure: indoor or outdoor use, salt, moisture, chemicals, machining after treatment and abrasion.
- Acceptance criteria: required standard, duration, permitted white or red rust, and assessment areas.
- Comparison plan: assess current and proposed systems under matching conditions; retain specimen photos and results.
- Production requirements: appearance, adhesion, subsequent processing, quantity and schedule, as well as corrosion resistance.
Providing both the acceptance criteria and the actual part conditions makes the evaluation more useful than choosing an isolated test-hour target.
Sources and scope
- ASTM B117-26: public scope and interpretation limits
- KEMP ELPANG performance table
- KEMP Innozinc characteristics
- KEMP Innozinc-h performance evidence
Based on the public information available on the update date. This guide supports initial technical review; use the current TDS, test report and project specification for application decisions.
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