JASO M 609:2024 Webinar Recap
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Last Updated 2026
Our final webinar of 2025 explored the latest updates to the Japanese automotive corrosion testing standard JASO M 609:2024. This release represents a major and comprehensive revision to the widely-used JASO M 609-91, a pioneering cyclic corrosion test featuring salt fog, humid, and drying phases, plus rapid transitions between steps.
The History of JASO M 609-91
Originally developed in 1991 by the Japanese Automotive Standards Organization, JASO M 609-91 was designed to evaluate the corrosion resistance of steel sheets used in automotive applications. At the time, existing cyclic corrosion tests did not consistently correlate with real-world exposure, leading to wide variation in testing practices across companies.
To address this, JASO conducted an extensive interlaboratory study involving more than 4,000 specimens. The resulting test method was designed to be accelerated while maintaining correlation to in-service performance, capable of evaluating both cosmetic and perforation corrosion. The test cycle includes salt fog, drying, and wetting phases compatible with commonly-available laboratory equipment of the time.
The test cycle also incorporated rapid transitions between steps in an effort to minimize variability. These fast transitions required more heating capacity than most corrosion test chambers could support at the time. In response to this challenge, Q-Lab introduced Rapid Ramp Heaters in 2020 to enable compliance with the test requirements.
Despite its strengths, JASO M 609-91 had limitations related to reproducibility, repeatability, and long-term correlation. While corrosion standards in the United States and Europe continued to evolve, this Japanese standard remained largely unchanged for over 30 years, making a revision necessary.
JASO M 609:2024 A Modernized Approach to Automotive Testing
The updated standard is based on extensive data collected from real-world outdoor corrosion exposure. Test protocols were evaluated against this data to determine the most representative approaches for inclusion in the new standard.
JASO M 609:2024 introduces three distinct test methods - Methods A, B, and C - all of which differ significantly from the 1991 version. Salt solution concentrations of 5 percent, 1 percent, and 0.5 percent are now all specified. Test cycle temperatures have been revised, and additional salt solution delivery techniques are permitted, including shower application in Method B and both shower and immersion in Method C. In addition, Method C also specifies an 85 percent relative humidity requirement - the first controlled RH value (not fully dry or fully humid) in a JASO M609 test.
The standard provides expanded guidance on specimen preparation prior to testing, as well as detailed post-exposure evaluation procedures for both cosmetic and perforation corrosion. While the new version retains familiar elements such as fog, humid, and dry steps, the overall structure and execution of the test are substantially different. As a result, it is no longer sufficient to reference JASO M 609 alone - the publication year and specific test method must now be clearly identified.
To stay current on JASO M 609:2024 and other accelerated and outdoor corrosion test standards, visit our Test Standards Page and explore our Standards Search Tool. Contact our team to learn how these updates may impact your testing programs and equipment needs.
Frequently Asked Questions
Q: Why was JASO M 609-91 updated?
A: The previous version of this standard had limitations in reproducibility, repeatability, and long-term correlation, and had not been revised for over 30 years.
Q: Is the updated standard still a cyclic corrosion test?
A: Yes. It retains fog, humid, and dry phases, but the cycle structure has been significantly updated.
Q: How is JASO M 609:2024 different from the 1991 version?
A: The updated standard introduces multiple test cycles, revised temperatures, new salt concentrations, controlled RH, and updated salt application techniques.
Q: Why must the test method now be specified when running this standard?
A: Because JASO M 609:2024 represents such a fundamental change in test parameters, users must identify both the publication year and the specific test method.
Q: How many test methods are included in the updated standard?
A: There are now three test methods available: Method A, Method B, and Method C.
Q: Are new salt application methods allowed?
A: Yes. Whereas JASO M 609-91 only permitted salt fog (mist), Method B allows shower application, and Method C allows either shower application and immersion.