ASTM B368 Corrosion/Salt Spray (CASS) Testing 

Overview of ASTM B368 Standard 

The ASTM B368 standard is a widely used method for corrosion and salt spray testing. Known as the Copper-Accelerated Acetic Acid Salt Spray (CASS) test, it assesses the durability of decorative and functional coatings in harsh environments. It is especially common in automotive, aerospace, and quality control applications. 

This test is particularly relevant for nickel-chromium and copper/nickel/chromium coatings, as well as anodized aluminum and die castings. It uses a salt solution of sodium chloride and copper chloride, acidified with acetic acid, and sprayed in a chamber at 49°C (120°F). Exposure times and result evaluations can be adjusted based on the product being tested. 

Due to its versatility, ASTM B368 is a key standard in metal finishing certification, corrosion testing for plastics, and research and development. 

Importance of Corrosion and Salt Spray Testing 

ASTM B368 and the CASS test are essential tools for engineers to evaluate coating durability in harsh environments. They are especially important in industries like automotive, aerospace, and electronics, where corrosion resistance impacts product lifespan. 

The CASS test simulates severe corrosion using salt spray, providing fast feedback on the durability of decorative coatings and anodized aluminum. This helps maintain quality control and meet customer standards. 

Manufacturers use ASTM B368 to detect coating weaknesses early, helping to avoid costly failures, warranty claims, and recalls. It also plays a key role in research and development by improving new coatings and treatments. 

For decorative hardware and anodizing, ASTM B368 sets a clear standard for coating performance. It supports process improvements and ensures product safety and reliability across multiple industries. 

Key Features and Benefits of ASTM B368 Testing 

ASTM B368 offers a controlled and repeatable environment for corrosion and salt spray testing, making it ideal for quality assurance and compliance. It uses a CASS test chamber with a copper chloride and acetic acid solution, maintaining strict temperature and pH levels for consistent results. 

The chamber runs at 49°C (120°F), with the solution’s pH closely monitored between 3.1 and 3.3. This ensures reliable testing across different labs and production sites. 

Proper sample preparation is crucial for accurate results. Coated samples must have sealed edges, and metal parts must be thoroughly cleaned. The method supports a wide range of sample sizes used in industries like aerospace, automotive, and decorative hardware. 

Test times vary from 24 to over 2,000 hours, depending on the product and purpose. Results contribute to detailed reporting, ensuring traceability and meeting regulatory requirements. 

Risk Management and the Role of Testing 

Risk management is a key benefit of ASTM B368 and the CASS test, helping engineers identify and address potential failures in coatings early. Integrating these tests into manufacturing and quality control reduces field failures, costly recalls, and customer dissatisfaction. 

The method’s repeatability and standardization ensure only coatings that meet strict safety and performance standards are approved for production. Testing also supports validation and ongoing process improvement, aligning with regulatory compliance and internal quality goals. 

Key benefits include: 

• Transparent ASTM B368 compliance reporting for audits and supplier evaluations 

• Benchmarking against performance metrics and acceptance criteria 

• Continuous improvement to meet or exceed industry standards 

This disciplined approach helps manufacturers maintain a competitive edge, especially in metal finishing certification and aerospace validation. 

Why Choose ASTM B368 as a Corrosion Testing Standard? 

ASTM B368 is the industry benchmark for corrosion and salt spray testing of decorative and functional coatings, known for its credibility and technical rigor. Its detailed procedures and equipment requirements are recognized globally by OEMs and regulatory bodies, ensuring coatings meet top performance and safety standards. 

The standard is widely adaptable, used in electroplating, automotive corrosion testing, and anodizing process validation. It supports various materials, including anodized aluminum, nickel chromium, and copper/nickel/chromium coatings. 

Key advantages of ASTM B368 include: 

• Strong emphasis on documentation and sample preparation 

• Traceable and auditable compliance reports 

• Proven track record in manufacturing quality control 

By adopting ASTM B368, manufacturers can demonstrate global compliance, improve reliability, and maintain a competitive edge across industries. 

How to Conduct ASTM B368 Corrosion/Salt Spray Testing 

Pre-Testing Preparation 

• Review the ASTM B368 standard and determine all relevant corrosion and salt spray test requirements for the component. 

• Prepare a detailed test plan, including: 

• ASTM B368 copper-accelerated acetic acid salt spray 

• ASTM B368 corrosion resistance evaluation 

• ASTM B368 sample preparation and cleaning 

• Prepare the test setup with the following equipment: 

• CASS test chamber or salt fog cabinet 

• Copper chloride solution and acetic acid solution 

• pH meter and temperature controller 

• Sample holders and specimen supports 

• Compressed air supply and atomizing nozzles 

Testing Procedures 

• Conduct sample preparation by thoroughly cleaning metallic samples and sealing cut edges of multilayer or coated specimens to avoid edge corrosion. 

• Prepare the CASS solution: mix 5 parts sodium chloride with 95 parts water, add reagent grade copper chloride dihydrate (1g per 4L), and adjust pH to 3.1–3.3 using glacial acetic acid. 

• Place samples in the test chamber, ensuring proper orientation and spacing for uniform exposure. 

• Maintain the exposure zone at 49°C (120°F) and ensure continuous atomization of the salt-copper solution. 

• Test durations can range from 24 to over 2,000 hours, depending on the product and specification requirements. 

Testing Report 

• Prepare a comprehensive ASTM B368 compliance report, including: 

• Test setup diagrams and equipment used 

• Detailed results for each test phase, including cross-section and thickness measurement 

• Performance metrics and acceptance criteria for corrosion resistance 

• Calibration records and traceability logs from pH meter and temperature controller 

• Any deviations, corrective actions, or retest outcomes 

Industry Applications and Relevance 

ASTM B368 is essential for corrosion testing, CASS testing, salt spray tests, and validating electrodeposited coatings. It is widely used in automotive corrosion standards, aerospace component validation, and decorative hardware testing. 

The standard covers anodized aluminum, nickel chromium, and copper/nickel/chromium coatings, supporting manufacturing quality control. Its compatibility with accelerated corrosion tests for various metals ensures broad industry acceptance. 

By adopting ASTM B368, manufacturers ensure their products are rigorously tested for durability, safety, and performance. This supports regulatory compliance and continuous improvement in corrosion engineering. 

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