Overview
EN ISO 19403-7:2024 - Paints and varnishes - Wettability - Part 7 specifies a standardized method to measure the dynamic contact angles and the roll-off angle of a liquid drop on a solid surface using a tilt stage. The method records how a drop behaves as the test surface is tilted at a constant speed, determining the dynamic advancing and dynamic receding contact angles from temporal tracking of the three‑phase line. The roll-off angle quantified by this standard is particularly relevant when evaluating easy-to-clean or anti‑adherent surfaces.
Key topics and technical requirements
- Measurement principle: Place a liquid drop on the specimen, tip the surface at a constant inclination rate until the drop rolls off; analyse the drop motion to obtain advancing and receding contact angles and the roll-off angle.
- Apparatus: State‑of‑the‑art contact angle measuring systems fitted with a tilting device. Digital image capture and analysis are preferred. Configurations may incline the camera and/or sample table.
- Dosing: Precise microsyringe/dosing units for microlitre‑scale drops.
- Test liquids: Analytical‑grade liquids. Water is specified with surface tension ≥ 71.5 mN/m at standard climate ((23 ± 2) °C, (50 ± 5) % RH). (Use of ethylene glycol as a test liquid has been removed in this edition.)
- Specimen preparation: Conditioning and minimum sample dimensions updated (minimum text sample size changed to 4 cm × 4 cm).
- Data capture and analysis: Temporal tracking of the wetting (advancing) and dewetting (receding) three‑phase points to derive dynamic contact angles; determination of the roll‑off angle when the drop detaches/rolls.
- Reporting: Test conditions, apparatus configuration, liquid properties, sample conditioning and measured angles must be recorded in the test report.
- Normative references: ISO 4618 (vocabulary) and ISO 19403‑1 (wettability vocabulary and principles).
Practical applications
- Evaluating self‑cleaning, anti‑soiling, and anti‑adherent coatings and surfaces.
- Comparing surface treatments, coatings and substrate finishes for cleanliness, liquid repellency and wetting behaviour.
- Quality control in paint, varnish and surface‑treatment production where dynamic wettability affects performance.
- Research and development of hydrophobic, oleophobic or structured surfaces where roll‑off behaviour is critical.
Who should use this standard
- Coating and surface engineers, material scientists and product developers
- Quality assurance and laboratory personnel in paints, varnishes and coating manufacturers
- Test laboratories performing wettability and surface property assessments
- R&D teams designing easy‑clean or anti‑adhesive surfaces
Related standards
- ISO 19403‑1 - Vocabulary and general principles for wettability
- ISO 4618 - Paints and varnishes - Vocabulary
Keywords: EN ISO 19403-7:2024, dynamic contact angles, roll-off angle, wettability, tilt stage, contact angle measurement, paints and varnishes, easy-to-clean surfaces.
