ECS’s Testing Capabilities Provides Peace of Mind for its Customer

Extreme Coating Solutions (ECS) operates multiple salt fog chambers to perform accelerated corrosion testing in accordance with ASTM B117. First published in 1939, ASTM B117 remains one of the most widely recognized and trusted corrosion test standards in use today.

For high‑performance organic and polymer coating systems, however, traditional salt fog testing can be time‑prohibitive. Validating premium systems often requires 1,000–4,000 hours of continuous exposure—equivalent to 41–170 days. In a market where product launches and design decisions move quickly, waiting several months for test results is often not realistic.

The Challenge: Fast Answers Without Compromising Confidence

A recent project illustrates this challenge. Our client was developing a coating system consisting of:

• A clear powder coat applied over polished aluminum
• A silane‑family clear coating as the final topcoat

Their original powder/silane system had already demonstrated excellent performance: more than 3,400 hours in ASTM B117 salt fog with acceptable results. The client now wanted to switch to a different powder coating chemistry but needed to understand:

• Would the new powder chemistry maintain the same level of corrosion resistance?
• Could they make this decision on a much shorter timetable than another 3,400+ hour test?

They needed reliable data long before a full 142‑day salt fog exposure could be completed.

Considering an Alternative: CASS Testing

To address the schedule constraint, ECS proposed incorporating a CASS (Copper‑Accelerated Acetic Acid Salt Spray) test following ASTM B368 as an additional tool.

For aluminum substrates, CASS testing is significantly more aggressive than standard salt fog. As a result, it can generate comparable failure modes much faster. As a rule of thumb, CASS can be up to eight times faster than ASTM B117 salt fog on aluminum—compressing what would be 142 days of exposure into roughly 18 days.

An uncoated aluminum panel placed in our CASS chamber for just under 48 hours showed extensive corrosion, clearly demonstrating the severity and efficiency of the test.

However, there is an important limitation:

• ASTM B117 and ASTM B368 are not interchangeable.
• The “8× faster on aluminum” relationship is only a rough guideline and is not sufficient by itself to justify a major material or process decision.

To be responsible, any use of CASS as a time‑saving tool must be backed by data that correlates CASS performance with traditional salt fog results for the **specific** coating systems under consideration.

Building a Data‑Driven Test Matrix

To mitigate risk and provide a defensible basis for the client’s decision, ECS designed a targeted testing matrix.

1. Coating Variants Tested

We prepared panels using the existing silane‑based topcoat over:

• The original powder coating chemistry (baseline, previously qualified at 3,400+ hours in B117)
• The new powder chemistry, in two versions:
  • With an adhesion promoter
  • Without an adhesion promoter

2. Adhesion & Interface Modeling

Before testing, our team developed computer simulation models to predict how the silane‑based clear coat would interact with the new powder chemistry. The modeling indicated that:

• The new powder system would likely require an adhesion promoter to achieve robust inter‑coat bonding.
• Without an adhesion promoter, the interface could become a weak link under corrosive conditions.

These insights informed the test matrix and allowed us to focus on the most critical variables.

3. Parallel Testing: CASS and Salt Fog

We then ran two identical sets of panels:

• One set in our CASS chamber (ASTM B368) for rapid, accelerated comparison.
• A second set in our salt fog chamber (ASTM B117) as a longer‑term validation and correlation tool.

The objective was not to replace salt fog testing with CASS, but to establish whether CASS results for this specific system could be relied upon to make an earlier, informed decision—then confirm that decision as the longer B117 test progressed.

Outcome: A Confident Path Forward

In a twist typical of real‑world projects, the client’s product launch was ultimately delayed long enough to nearly coincide with completion of the extended ASTM B117 test.

By that time:

• The CASS and salt fog results were in strong agreement.
• Both test methods confirmed that the new powder chemistry, when used with the adhesion promoter, delivered performance comparable to the original, previously qualified system.
• Panels using the new powder without the adhesion promoter did not perform to the same standard, validating the importance of the promoter identified by our modeling work.

Armed with correlated data from both CASS and salt fog testing—and a clear understanding of the role of the adhesion promoter—our client was able to confidently move forward with the new powder coating chemistry while maintaining the corrosion performance their customers expected.

ECS: Integrated Testing, Analysis, and Development Support

Extreme Coating Solutions maintains a broad range of analytical and testing capabilities to support:

• Quality assurance and validation
• New coating product development
• Failure analysis and troubleshooting
• R&D and process optimization

Our lab equipment and services include, but are not limited to:

• Thermo Fisher iS10 FTIR spectrometers
• Corrosion testing (ASTM B117, ASTM B368, and others)
• Adhesion, hardness, and chemical resistance testing
• Custom test matrix design and data interpretation

If you’re evaluating new coating chemistries or need to compress development timelines without sacrificing confidence, ECS can help design a test strategy that balances speed, cost, and risk.

For more information, contact:

Jim Stuelke, CEO
Phone: 816‑381‑9901
Email: info@nullecs-ww.com