ISO 19403-6:2024

Overview

ISO 19403-6:2024 - Paints and varnishes - Wettability - Part 6 specifies an optical method for measuring the dynamic advancing and dynamic receding contact angles by continuously changing the volume of a liquid drop on a flat surface. The standard defines how to characterize wetting and dewetting behavior and assess morphological and chemical homogeneity of interfaces using dynamic contact-angle measurements.

Key topics and requirements

• Scope & principle
  • Measures dynamic contact angles while the three‑phase contact line advances (volume increase) or recedes (volume decrease).
  • Preferred contact-angle evaluation by image analysis (e.g., polynomial fitting) synchronized with dosing.
• Apparatus & materials
  • State‑of‑the‑art contact angle measuring system with digital image capture, optical system and microlitre dosing syringe.
  • Dosing unit capable of continuous microlitre-range volume change (typical dosing ~10 µl/min for surface energy tests).
  • Test liquids that do not chemically alter the surface, do not form skins or crosslink, and have acceptable volatility (special handling if vapour pressure exceeds 42 470 hPa as noted).
• Sampling & specimen preparation
  • Representative, uncontaminated specimens (preferably ≥ 4 cm × 4 cm), prepared per ISO 15528 and conditioned as specified.
• Test conditions & procedure
  • Ambient conditions: (23 ± 2) °C and (50 ± 5) % RH (unless otherwise agreed); condition liquids and panels before testing.
  • Camera alignment, needle distance, dosing speed and baseline alignment are specified to reduce measurement bias.
• Evaluation
  • Determine dynamic advancing angle (θa), dynamic receding angle (θr), and contact angle hysteresis (θar = θa − θr).
  • Note: dynamic receding contact angle is not recommended for surface energy determination; the dynamic advancing contact angle should be used when applying ISO 19403-2.

Applications

• Quality control and R&D in coatings, paints and varnishes to:
  • Characterize wetting and dewetting properties of substrates and coatings.
  • Evaluate surface homogeneity (chemical and morphological) and detect defects or contamination.
  • Provide input data for surface free energy analysis (in combination with ISO 19403-2).
• Used by: coatings manufacturers, surface science laboratories, materials scientists, formulation chemists, and regulatory/QA teams.

Related standards

• ISO 19403-1:2022 - Vocabulary and general principles (wettability)
• ISO 19403-2:2024 - Surface free energy determination by contact angle
• ISO 4618 - Paints and varnishes vocabulary
• ISO 15528 - Sampling for paints and varnishes

Keywords: ISO 19403-6:2024, dynamic contact angle, dynamic advancing contact angle, dynamic receding contact angle, wettability, contact angle hysteresis, contact angle measuring system, surface free energy, paints and varnishes.