Overview
EN ISO 19403-2:2024 - Paints and varnishes - Wettability - Part 2 specifies a laboratory test method for determining the surface free energy of solid surfaces by measuring the contact angle of liquid drops. The method is intended for characterization of substrates and coatings (excluding powders) and is based on state-of-the-art drop projection in penumbral shadow with digital image capture and analysis. For polymers and coatings the standard prefers the Owens–Wendt–Rabel–Kaelble (OWRK) or Wu evaluation methods. Key normative references include ISO 4618 and ISO 19403-1.
Key Topics and Requirements
- Measurement principle: Dose a minimum of three drops of at least two test liquids onto a flat specimen, measure contact angles and calculate surface free energy divided into polar and dispersive components.
- Apparatus: Modern contact angle measuring systems (digital imaging), precise dosing units (microlitre range) and appropriate optical setup. Camera tilt and imaging resolution are specified for reliable results.
- Test specimen: Requirements for sample conditioning and minimum sample size (updated to 4 cm × 4 cm in the 2024 edition).
- Evaluation methods: Recommended calculation approaches are the OWRK method and the Wu method for polymers and coatings; procedures for static and dynamic (progressive) contact angle measurement are included.
- Influencing factors: Notes on morphological and chemical homogeneity of the surface, and guidance on sampling, conditioning and measurement practice.
- Exclusions: Contact angle measurement on powders is not covered.
Applications
EN ISO 19403-2:2024 is used to:
- Characterize surface wettability and adhesion potential of substrates, coatings and treated surfaces.
- Support coating formulation, surface pretreatment and process development (e.g., cleaning, priming, plasma or chemical treatments).
- Provide quantitative data for quality control, failure analysis and specification compliance in paint and varnish manufacturing.
- Aid material selection in industries where wetting and adhesion are critical (automotive, aerospace, electronics, packaging, construction).
Who uses this standard
- Coating formulators and R&D scientists
- Surface and materials characterization labs
- Quality control/assurance teams in manufacturing
- Test laboratories, certification bodies and academic researchers
Related Standards
- ISO 19403-1 - Vocabulary and general principles for wettability
- ISO 4618 - Paints and varnishes - Vocabulary
- Other parts of the ISO 19403 series covering specific wettability aspects and methods
Keywords: EN ISO 19403-2:2024, contact angle, surface free energy, wettability, paints and varnishes, OWRK method, Wu method, drop projection, contact angle measurement.
