ISO 19403-2-2024 PDF

Full title and description

Paints and varnishes — Wettability — Part 2: Determination of the surface free energy of solid surfaces by measuring the contact angle. This international standard specifies an optical test method for measuring contact angles and using those measurements to determine the surface free energy (including recommended calculation approaches) of solid substrates and coatings.

Abstract

This document defines a contact-angle-based test procedure (drop projection method in penumbral shadow) to measure the contact angle on solid surfaces and to calculate the surface free energy of those surfaces. It describes preferred calculation approaches (for example Owens–Wendt (Rabel and Kaelble) and Wu methods for polymers and coatings), notes limitations related to morphological and chemical homogeneity, and states that contact-angle measurement on powders is outside the scope.

General information

• Status: Published (International Standard).
• Publication date: September 2024 (published 4 September 2024 in vendor listings).
• Publisher: International Organization for Standardization (ISO), Technical Committee ISO/TC 35/SC 9 (Paints and varnishes — Wettability).
• ICS / categories: 87.040 (Paints and varnishes).
• Edition / version: Edition 2 (2024).
• Number of pages: 14 pages (ISO published edition).

Scope

The standard specifies a laboratory test method to measure static contact angles on solid surfaces by optical observation of liquid drops and to derive the surface free energy of the solid. It applies to substrates and applied coatings; it excludes contact-angle measurements on powders and highlights that heterogeneous or morphologically non‑uniform surfaces can affect results. Preferred calculation methods for polymers and coatings (Owens–Wendt / Rabel–Kaelble and Wu) are indicated.

Key topics and requirements

• Measurement of static contact angle using the drop-projection (penumbral shadow) optical method.
• Procedures for calculating surface free energy from contact-angle data (including Owens–Wendt and Wu approaches as preferred methods for polymers/coatings).
• Notes on influence of surface morphology and chemical homogeneity on measurement accuracy and interpretation.
• Exclusion: measurement on powders is not covered.
• Alignment with other parts of the ISO 19403 series (vocabulary/principles, liquid surface-tension methods, polar/dispersive fraction determination).

Typical use and users

Laboratories and R&D groups in coatings, adhesives, plastics and surface-treatment industries; quality control teams assessing substrate wettability and coating compatibility; instrument manufacturers and calibration/testing services for contact-angle and surface-energy measurement; academic researchers studying surface interactions and interfacial phenomena. Users rely on the method to characterize substrate/coating surface energy for adhesion, coating wetting and formulation decisions.

Related standards

ISO 19403 is a multi-part series. Relevant related parts include ISO 19403-1:2022 (vocabulary and general principles), ISO 19403-3:2024 (surface tension of liquids — pendant drop), ISO 19403-4:2024 (polar/dispersive fractions from interfacial tension) and other parts in the 19403 series covering dynamic contact angle and roll-off measurements. ISO 4618 (paints and varnishes — vocabulary) is also referenced for terminology.

Keywords

contact angle, surface free energy, wettability, paints and varnishes, surface tension, Owens–Wendt, Wu method, drop projection, penumbral shadow, contact-angle measurement, ISO 19403 series.

FAQ

Q: What is this standard?

A: ISO 19403-2:2024 is an international standard that specifies an optical contact-angle test method and associated calculation procedures to determine the surface free energy of solid surfaces (substrates and coatings).

Q: What does it cover?

A: It covers measurement of static contact angles by the drop-projection (penumbral shadow) method and calculation methods to derive surface free energy (including recommended approaches for polymers and coatings). It does not cover contact-angle measurement on powders and warns about effects of surface heterogeneity on results.

Q: Who typically uses it?

A: Coatings and adhesive formulators, surface‑characterization laboratories, QA/QC teams, instrument manufacturers and researchers requiring standardized contact-angle procedures and a consistent method to estimate solid surface energy for adhesion and wetting assessments.

Q: Is it current or superseded?

A: Current — the 2024 edition (Edition 2) was published in September 2024 and replaces the earlier ISO 19403-2:2017, which has been withdrawn.

Q: Is it part of a series?

A: Yes — ISO 19403 is a multipart series on wettability and optical test methods; Part 1 covers vocabulary and principles (2022), and other parts (2024) cover liquid surface-tension methods and related surface-energy determinations. Users should consult the series for complementary methods and definitions.

Q: What are the key keywords?

A: contact angle; surface free energy; wettability; drop projection; Owens–Wendt; Wu; surface tension; coatings; substrates.