A Simple, Repeatable Continuous Salt Fog Test
ISO 9227, along with ASTM B117, is the most widely-used corrosion test method worldwide. It is a salt spray (fog) test for assessing the corrosion resistance of metals and coatings. With a salt fog environment continuously applied at constant temperature, materials are rigorously tested to simulate harsh conditions. The addition of acidic solutions enables even faster testing of highly durable materials. This proven method provides insights into durability and performance, helping manufacturers ensure their products stand up to the elements.
Test Parameters
- Salt spray: Continuous atomized salt fog
- Solution
- Neutral: 5% Sodium Chloride solution (pH 6.5 - 7.2)
- AASS: 5% Sodium Chloride solution acidified with acetic acid (pH 3.1 - 3.3)
- CASS: 5% Sodium Chloride solution acidified with acetic acid plus copper (II) chloride (pH 3.1 - 3.3)
- Temperature
- Neutral, AASS: 35 °C
- CASS: 50 °C
- Collections: 1-2 mL/hr when collected in an 10 cm (4 in) diameter funnel
- Corrosion coupons: CXD-2.76-5.90
Why Test to ISO 9227?
ISO 9227 is used in many industries & applications including the automotive, construction, aerospace, consumer goods & electronics, metals, and paint & coatings industries. three different tests are available:
- The NSS test is particularly applicable to metals, alloys, metallic and conversion coatings, anodic oxide coatings, and organic coatings
- The AASS and CASS tests are especially useful for testing decorative coatings of copper + nickel + chromium, or nickel + chromium. It has also been found suitable for testing anodic and organic coatings on aluminium.
While ISO 9227 doesn’t necessarily create excellent correlation to outdoor corrosive conditions, it produces results very quickly and has better repeatability and reproducibility than any other test, making it ideal for quality control testing of corrosion resistance.
Pros and Cons of ISO 9227
- Long History and Broad Acceptance
- ISO 9227 is widely recognized internationally, making it easy to compare to historical and published data. It's a globally-accepted test for corrosion evaluation.
- Simple and Cost-Effective
- This test method is inexpensive in comparison to other advanced corrosion testing methods. Additionally, the test itself is relatively easy to perform.
- Reproducibility and Repeatibility
- The simple, non-cyclic nature of ISO 9227 allows for very good consistency from test to test, laboratory to laboratory.
- Wide Range of Applications
- ISO 9227 is used across many industries, including automotive, aerospace, marine, and electronics.
- Fast results
- The acidified options in ISO 9227 may not correlate well to outdoors, but provide a harsh test for highly-durable coatings.
- Not always representative of real-world conditions
- The test conditions do not accurately replicate real environmental conditions like humidity, temperature fluctuations, complex salts, or industrial pollutants, and may not reproduce all relevant corrosion types.
- Overly harsh testing
- While the acid-accelerated tests in ISO 9227 can cause damage quickly, it may be more severe than actual use environments.
- Over-emphasis of surface corrosion
- The test focuses on how coatings perform under salt exposure, but doesn’t fully evaluate their protection against underlying metal corrosion.
- Incomplete results
- Some materials or coatings may pass the ISO 9227 test but fail in real-world scenarios due to differences in environmental factors that aren’t simulated by the test, like UV exposure or cyclic natural conditions
How Q-Lab Can Help
Q-FOG Cyclic Corrosion Test Chambers
Cyclic corrosion testing provides the best laboratory simulation of natural atmospheric corrosion. In just a few days or weeks, Q‑Lab’s line of Q‑FOG test chambers can reproduce the damage that occurs over months or years outdoors.
Test Services
Q-Lab offers a full range of laboratory testing services in our fully-equipped laboratories in Florida and Germany. We can perform everything from simple salt spray testing to modern automotive cyclic corrosion tests. Laboratory corrosion testing can be used for quality control, material certification, durability studies, and independent third-party verification.
Q-PANEL Standard Test Substrates
Q‑PANEL paint test substrates are the world’s most recognizable and widely-used standard test panels. Q‑Lab manufactures millions of panels each year for a variety of industries, most available immediately from stock. Q‑Lab’s CX-series mass-loss corrosion coupons ensure repeatability and reproducibility when performing laboratory corrosion testing. CXD-2.76-5.90 coupons meet the requirements of ISO 9227.
More ISO 9227 Resources
Standards Tool
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