Corrosion is one of the main challenges when it comes to protecting metal surfaces. To guarantee the durability of a paint coating, it is essential to assess its effectiveness against the appearance of rust. Standard NF EN ISO 4628-3 defines an international reference method for measuring the degree of curling.
What is the degree of curl?
Rust curl is the propagation of rust under the paint film, which eventually appears on the surface. This indicator reveals the coating's ability to prevent corrosion, and is an essential criterion for monitoring anti-corrosion performance.
A standardized method for paint coatings
Standard NF EN ISO 4628-3 is based on a visual scale from Ri 0 to Ri 5, defining the percentage of corroded surface:
- Ri 0: no visible rust
- Ri 1 to Ri 2: slight curl (≈ 0.05 to 0.5% of surface)
- Ri 3 to Ri 4: moderate to significant corrosion (≈ 1 to 8%)
- Ri 5: extended winding (≈ 40 to 50%)
This simple, standardized classification facilitates quality control of industrial coatings, monitoring over time and comparison between different production batches.
Opiqa-Lab: Imasolia's platform for industrial analysis
- At Imasolia, we have developed Opiqa-Lab, a platform dedicated to industrial analysis in laboratory mode.
- Opiqa-Lab integrates optical non-destructive testing methods to assess various surface parameters, including the degree of curl in accordance with NF EN ISO 4628-3. With this approach, we bring greater precision, reproducibility and speed to coating assessment, while reducing the subjectivity associated with visual inspection.
Conclusion: reliability and anti-corrosion performance
Analysis of the degree of curl according to NF EN ISO 4628-3 is an essential lever for guaranteeing the performance of paint coatings against corrosion. By combining this reference method with our optical non-destructive testing solutions, we offer manufacturers a reliable and innovative tool for extending the life of their equipment and securing their processes.
FAQ on degree of winding and ISO 4628-3 standard
What is the degree of curl?
The degree of curl measures the spread of rust under a paint coating. It indicates the proportion of the surface affected by visible corrosion.
What does NF EN ISO 4628-3 define?
This international standard provides a standardized visual method for assessing rusting, using a scale from Ri 0 (no rust) to Ri 5 (extensive rust).
Why is winding assessment important for the industry?
This analysis enables us to control coating quality, compare production batches and anticipate maintenance requirements. It is essential for the durability of metal equipment.
How does Imasolia innovate in this area?
We have developed an optical non-destructive testing tool capable of automatically assessing the degree of curl. This technology increases precision, reduces subjectivity and speeds up industrial inspections.