In conjunction with the Marine Energy Engineering Centre of Excellence (MEECE), Hexigone embarked on a rigorous real-world test of their anticorrosion additive, Intelli-ion AX1. From September 2022 to June 2023, 31 sets of panels were attached to a buoy. Deployed in a unique test location, they endured more than 6,000 hours, battling the formidable forces of the Celtic Sea.

The Test Setup: Panels and Preparation

The panels used in this project were constructed from low-carbon, cold-rolled steel featuring a matte finish. These panels are typically used in general-purpose sheet metal applications and adhere to ASTM A1008, A-109, and QQ-S-698 standards.

To ensure a thorough evaluation, the panels were coated with various types of anticorrosion coatings:

Solventborne Alkyd

Painted with a paintbrush:

• Four panels were painted with a co-blend of 3% AX1 and 2% zinc phosphate.

• Four panels were painted with 5% AX1 only.

Solventborne 2-Pack Epoxy

Spray-painted with a compressed air paint gun:

• Four panels were painted with 0% AX1.

• Four panels were painted with a co-blend of 5% AX1 and zinc phosphate.

All solventborne 2-pack epoxy primers contained zinc phosphate anticorrosive pigments, resulting in all epoxy-coated panels possessing a blend of anticorrosive substances for comparing co-blend panels against industry standards.

Waterborne Acrylic

• Eight panels were painted with a co-blend of 2% AX1 and 2% polyphosphate.

These panels were also intentionally damaged. An 'X' was scribed into the coating to expose the bare metal using a 0.5 mm Elcometer scratching tool, simulating damage to the paint system that can occur in real-world applications.

The Testing Rig: A Bespoke Solution

To withstand the rigors of the Celtic Sea, a custom-designed test rack was engineered by the skilled engineers at MEECE to securely mount the panels onto the buoy.

The panels were fixed flat against a drilled plastic backing board, held in place by plastic bolts, washers, and nuts, with additional support from a holding strip at the bottom. This setup ensured the panels remained secure throughout the test duration, even under extreme weather conditions.

FIGURE 1 | Exploded assembly view of the basic panel mounting concept for two adjacent panels.

Figures 2 and 3 below captured two key stages: the initial assembly of the panels onto the test rack, followed by the final installation of the test rack onto the buoy.

FIGURE 2 | The initial assembly of the panels onto the test rack.

FIGURE 3 | The final installation of the test rack onto the buoy.

Monitoring

The panels were monitored over a period of nine months, with inspections at key intervals to assess damage and track the progression of corrosion.

Installation Day – Sept. 21, 2022

FIGURE 4 | Day 1, 24 hours.

Nov. 14, 2022

FIGURE 5 | Day 54, 1,296 hours.

Last Day – June 8, 2023

FIGURE 6 | Day 260, 6,240 hours.

The Results

After 6,000 grueling hours of battling the elements, it was time to recover the panels for analysis—the results were both surprising and promising.

Solventborne Alkyd – 6,000 Hours of Live Coastal Testing

FIGURE 7 | Solventborne alkyd. 

The results from both formulations are strikingly similar, demonstrating high performance for both the co-blend of 3% AX1 and 2% zinc phosphate (left) and the AX1-only formulation (right). When stripped with solvent, their performance remains consistently high, with corrosion localized at the scribe line and minimal overall. The full metal substrate beneath the coating remains fully protected, highlighting the effectiveness of the anticorrosive formulation.

Solventborne 2-Pack Epoxy – 6,000 Hours of Live Coastal Testing

FIGURE 8 | Solventborne 2-pak epoxy. 

Formulated with a 5% addition of AX1, the panels on the right clearly showcase enhanced durability and coating adhesion compared to the panels on the left, with 0% AX1. Despite being coated with alternative anticorrosive pigments, the left panels show significant degradation—nearly completely destroyed.

Waterborne Acrylic – 6,000 Hours of Live Coastal Testing

FIGURE 9 | Waterborne acrylic. 

The waterborne acrylic panels have demonstrated remarkable performance under real-world conditions, showing consistent results across all panels even after being stripped with solvent to reveal the underlying results. Notably, only the primer contained AX1; the topcoat did not.

FIGURE 10 | Solventborne 2-pak epoxy vs. waterborne acrylic. 

Among all the results, the performance of the waterborne acrylic panels is particularly noteworthy—exceeding expectations and even surpassing the solventborne 2-pack epoxy coatings in real-world conditions.

Even after stripping both sets of panels with solvent to reveal the underlying results, the contrast remains striking—the waterborne acrylic panels containing AX1 dramatically outperform the solventborne 2-pack epoxy panels.

The waterborne acrylic formulation was developed in collaboration with Xyntra.

David Graham, the managing director of Xyntra, commented: "We are highly impressed with the performance of AX1 and have been collaborating closely with Hexigone to design a polymer system that leverages its capabilities in a water-based application. The results so far have been very encouraging.

Adhesion – 6,000 Hours of Live Coastal Testing

FIGURE 11 | Waterborne acrylic adhesion. 

The addition of AX1 also significantly improved the adhesion of the waterborne acrylic paint system. During the pull-off test, only the topcoat could be removed, while the primer layer remained firmly fastened to the metal substrate. The dollies were removed at 450 psi and 300 psi.

Conclusion

The outcomes of this investigation have provided Hexigone with valuable, actionable insights. The buoy panels endured over 6,000 hours of coastal testing, offering a true assessment of the paint systems' ability to withstand harsh environmental conditions.

As expected, the panels treated with Intelli-ion AX1 demonstrated a significant improvement in corrosion resistance compared to those without AX1. However, the most unexpected finding was the exceptional performance of the waterborne acrylic panels.

With the industry increasingly shifting toward more sustainable solutions and away from coatings containing volatile organic compounds (VOCs) and other hazardous chemicals, the demand for waterborne acrylic coatings is rapidly growing. These findings suggest that Intelli-ion AX1 has the potential to accelerate the broader adoption of waterborne acrylic coatings in marine applications.

The results also highlight AX1’s ability to enhance corrosion resistance across multiple coating types, reinforcing its versatility as an additive for high-performance protective coatings. As Hexigone continues to innovate, this real-world data will support further research and development efforts, ensuring that the industry moves toward more durable and environmentally responsible solutions.

*All images courtesy of Hexigone.