Appendix A
Description of Methods for Corrosion Testing
Written and technically reviewed by: Michel Comtois, M. Sc. Chemistry and
Anne-Marie Comtois, ChE, August 1, 2026
A complete reference of the corrosion testing methods referenced throughout this guide, including cycle steps, electrolyte solution, and pH range for each standard.
| Standard | Cycle | Note | Solution | pH | Cycle steps |
|---|---|---|---|---|---|
| ASTM B117 | — | General: fine mist (atomized with compressed air) sprayed indirectly onto specimens | 5 ± 1% NaCl | 6.5–7.2 | 100% Fog @ 35 ± 2°C |
| ASTM G85 | A1 | Acetic acid salt spray | 5 ± 1% NaCl + acetic acid to required pH | 3.1–3.3 | 100% Fog @ 35 ± 2°C |
| ASTM G85 | A2 | Cyclic acidified salt fog | 5 ± 1% NaCl | 2.8–3.0 | 0.75h Fog @ 49 ± 2°C 2h Dry air purge 3.25h Humidity |
| ASTM G85 | A3 | Acidified synthetic seawater | Synthetic sea salt | 2.8–3.0 | 0.5h Fog @ 24 to 35 or 49 ± 2°C 1.5h Humidity |
| ASTM G85 | A5 | Dilute electrolyte cyclic fog/dry | 0.35% (NH₄)₂SO₄ + 0.05% NaCl | 5.0–5.4 | 1h Fog 1h Dry @ 35 ± 1.5°C |
| ASTM D2247 | — | Humidity | — | — | 100% Relative Humidity @ 38 ± 2°C |
| ASTM E1925 | 7.12 | Humidity resistance for rigid wall | — | — | 20h >97% Relative Humidity 4h 100% Relative Humidity |
| ASTM E1925 | Marine atmosphere | Marine atmosphere for rigid wall | 10% | 6.5–7.2 | 96h Fog @ 35 ± 2°C |
| MIL-STD-810G 509.5 | — | Salt fog | 5 ± 1% NaCl | 6.5–7.2 | 24h Fog @ 35 ± 2°C 24h Ambient dry |
| ISO 9227 | NSS | Neutral salt spray | 5 ± 1% NaCl | 6.5–7.2 | 100% Fog @ 35 ± 2°C |
| ISO 9227 | AASS | Acetic acid salt spray | 5 ± 1% NaCl | 3.1–3.3 | 100% Fog @ 35 ± 2°C |
| ISO 9227 | CASS | Copper-accelerated acetic acid salt spray. For the quality control of inorganic coating systems. | 5 ± 1% NaCl + 0.26 g/l CuCl₂·2H₂O | 3.1–3.3 | 100% Fog @ 50 ± 2°C |
| ASTM D1735 | — | Testing water resistance of coatings using water fog apparatus | Water conforming to Type IV or better of Specification D1193 | — | 100% Relative Humidity @ 38 ± 2°C |
| ASTM D5894 | — | Cyclic salt fog/UV exposure of painted metal | 0.35% (NH₄)₂SO₄ + 0.05% NaCl | 5.0–5.4 | 1 week — UV (ASTM G154) 1 week — ASTM G85 A5 with modified solution |
| ISO 11997 | Cycle A | Wet (salt fog) / dry / humid | 5 ± 1% NaCl | 6.0–7.0 | 2h salt fog @ 35 ± 2°C 4h 60 ± 2°C @ 20–30% RH 2h 50 ± 2°C @ >95% RH |
| ISO 11997 | Cycle B | Wet (salt fog) / dry / humid | 5 ± 1% NaCl | 6.0–7.0 | 24h salt fog @ 35 ± 2°C 8h 40 ± 2°C @ 100% RH 16h 23 ± 2°C @ 50 ± 20% RH (× 4 repeats) 48h 23 ± 2°C @ 50 ± 20% RH |
| ISO 11997 | Cycle C | Wet (salt fog) / dry / humid | Sodium chloride (0.31 ± 0.01) g/l + ammonium sulfate (4.1 ± 0.01) g/l | 6.0–7.0 | 210 min salt fog @ 30 ± 2°C 210 min dry @ 40 ± 2°C 1470 min dry @ 40 ± 2°C @ 75 ± 15% RH 102 min dry @ 30 ± 2°C 210 min salt fog @ 30 ± 2°C 378 min dry @ 30 ± 2°C @ 95–100% RH 180 min dry @ 35 ± 2°C 120 min dry @ 25 ± 2°C |
| ISO 11997 | Cycle D | Wet (salt fog) / dry / humid | 5 ± 1% NaCl | 6.0–7.0 | 0.5h salt fog @ 30 ± 2°C 1.5h 30 ± 2°C @ 95 ± 3% RH 2h dry @ 50 ± 2°C 2h dry @ 30 ± 2°C |
| SAE J2334 | — | Laboratory cyclic corrosion test | 0.075% NaHCO₃ + 0.5% NaCl + 0.1% CaCl₂ | — | 6h @ 50 ± 2°C @ 100% RH 15 min salt application at ambient 7h 45min @ 60°C @ 50% RH |
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