Overview
EN ISO 29601:2026, titled Paints and varnishes - Corrosion protection by protective paint systems - Assessment of porosity in a dry film, is a European standard developed by CEN. This standard defines procedures for detecting porosity in protective paint and varnish systems on steel or other metallic substrates. Porosity assessment is essential in ensuring the long-term corrosion protection provided by coatings applied in demanding industrial and infrastructure environments.
The standard applies to paint systems of any thickness, provided they contain electrically non-conductive components. It details two principal testing methods - the use of low-voltage pinhole detectors and high-voltage holiday detectors - to suit different dry film thicknesses. The guidance is relevant for both newly applied coatings and, with care, coatings that have been in service.
Key Topics
Porosity Detection Methods
- Low-voltage pinhole detectors: Typically used for coatings up to 500 µm. These use a wetted sponge and battery-powered device to detect discontinuities.
- High-voltage holiday detectors: Required for dry film thickness above 500 µm. These systems generate a spark to reveal defects, using a probe and calibrated voltage settings.
Test Procedure Highlights
- Test method selection depends on dry film thickness.
- Proper surface preparation and grounding are critical for accurate results.
- Test voltages must be set according to film thickness for reliable detection.
- Results are reported as the number of discontinuities found in the inspection area.
Applications
EN ISO 29601:2026 serves a range of sectors where corrosion protection of metals is crucial, including:
- Industrial Infrastructure: Bridges, storage tanks, pipelines, and offshore platforms rely on protective coating systems to prevent corrosion-related failures.
- Manufacturing and Maintenance: New installations and maintenance operations benefit from quality assurance through porosity assessment.
- Quality Control: Paint manufacturers, applicators, and inspection agencies use these methods to verify the integrity of protective coatings before and after deployment.
- Regulatory Compliance: Reference in national and project specifications ensures coatings meet required performance standards.
Practical use of this standard helps identify holidays, pinholes, cracks, voids, and other discontinuities that can compromise corrosion protection, thus supporting durability and reducing lifecycle costs.
Related Standards
EN ISO 29601:2026 complements several international and European standards for protective paint and varnish systems:
- ISO 12944 series: Addresses all aspects of corrosion protection by paint systems, including design, implementation, and maintenance.
- ISO 19840: Specifies measurement and acceptance criteria for dry film thickness of protective paints on rough surfaces.
- ISO 16276-1/2: Covers assessment and acceptance criteria for the adhesion/cohesion strength of coatings.
- ISO 4628 series: Provides methods for evaluating degradation of coatings, such as blistering, rusting, and cracking.
- ISO 2808: Outlines methods for determining coating film thickness.
Referencing these standards in combination ensures comprehensive and standardized evaluation of protective coating performance, from surface preparation through to long-term inspection.
Keywords: EN ISO 29601:2026, porosity assessment, protective paint systems, corrosion protection, dry film testing, pinhole detector, holiday detector, industrial coatings, quality control, paint and varnish standards, steel protection.