EN ISO 4624:2023 PDF

Overview

EN ISO 4624:2023 - Paints and varnishes: Pull-off test for adhesion (ISO 4624:2023) is the CEN-endorsed international method for assessing adhesion of single or multi-coat paint and varnish systems by a controlled tensile (pull-off) test. The standard specifies three distinct test methods (A, B and C) using bonded dollies and a tensile tester to measure the force required to detach or rupture a coating perpendicular to the substrate. EN ISO 4624:2023 supersedes EN ISO 4624:2016 and includes technical updates such as added guidance for larger dollies (up to 100 mm) for concrete and new requirements on adhesive selection relative to substrate/coating materials.

Key Topics and Requirements

• Three methods prescribed
  • Method A: Two-dolly (sandwich) configuration - suitable for rigid and deformable substrates (thin metal, plastics, wood).
  • Method B: Single-dolly testing from one side - suitable for rigid substrates only.
  • Method C: Use of dollies where one dolly acts as the painted substrate (special configurations).
• Substrate considerations: Different procedures are given for deformable vs rigid substrates; sandwich constructions are recommended to avoid substrate distortion.
• Adhesives and dollies: Dollies are bonded to cured coatings using suitable adhesives; the standard includes requirements for adhesive selection and dolly sizes (including larger sizes for concrete).
• Measurements and results: The test records breaking strength (tensile stress at failure) and the nature of the fracture (adhesive/cohesive failure), providing relative adhesion ratings.
• Preparation and conditioning: Specifies sample preparation, coating application, drying/curing, thickness control and ambient conditioning in line with referenced ISO documents.
• Precision and reporting: Includes guidance on number of determinations, ambient conditions, and the required content of test reports.

Applications and Users

• Practical uses
  • Quality control for paint and coating production
  • Comparative R&D testing of coating formulations and surface treatments
  • Service-life qualification and specification compliance
  • Failure analysis and root-cause investigation of coating breakdown
• Who uses it
  • Coatings manufacturers and formulators
  • Independent test laboratories and QC departments
  • Specifiers, architects and contractors for protective coatings (metal, concrete, wood, plastics)
  • Research institutions studying adhesion performance

Related Standards

• ISO 1513 - Examination and preparation of test samples
• ISO 1514 - Standard panels for testing
• ISO 2808 - Determination of film thickness
• ISO 3270 - Temperatures and humidities for conditioning and testing
• ISO 4618 - Paints and varnishes vocabulary
• ISO 15528 - Sampling
• ISO 2409 - Cross-cut test (alternative adhesion evaluation)

EN ISO 4624:2023 is essential for anyone specifying or testing coating adhesion, offering standardized, reproducible pull-off test methods for a wide range of substrates and industrial applications.