ISO 19403-3-2024 PDF

Full title and description

Paints and varnishes — Wettability — Part 3: Determination of the surface tension of liquids using the pendant drop method (ISO 19403-3:2024). This international standard specifies an optical pendant-drop test method for measuring the surface tension of liquids, primarily for characterizing liquid coating materials; it includes guidance on applicability and limitations for non-Newtonian fluids.

Abstract

This document describes the pendant-drop optical technique to determine liquid surface tension. It defines test preparation, drop formation and imaging, image analysis and calculation of surface tension from drop shape, and notes restrictions when applied to non-Newtonian coating materials. The method is intended for laboratory and R&D use as well as quality control of liquid coatings.

General information

• Status: Published.
• Publication date: 4 September 2024 (Edition 2).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 87.040 — Paints and varnishes.
• Edition / version: Edition 2 (2024).
• Number of pages: 11 pages (ISO published document).

Scope

This part of ISO 19403 specifies a laboratory test method to measure the surface tension of liquids using an optical pendant-drop technique. It is intended for characterizing liquid coating materials and related liquids; when applied to liquids exhibiting non-Newtonian flow behaviour (as defined in ISO 3219-1:2021) restrictions and additional considerations may apply. The standard notes alternative methods (for example EN 14370, ISO 1409) for surface-tension determination.

Key topics and requirements

• Principle and purpose: measurement of surface tension from pendant-drop profile using optical imaging and drop-shape analysis.
• Apparatus and materials: requirements for syringe/nozzle, imaging system (magnification, resolution), temperature control and calibration.
• Specimen preparation and drop formation: procedures for forming reproducible drops and avoiding dynamic artifacts.
• Image capture and analysis: recommended imaging settings, edge detection and curve-fitting methods to derive surface tension from the drop profile.
• Accuracy, repeatability and uncertainty: factors affecting measurement uncertainty and guidance for reporting results.
• Limitations and applicability: notes on non-Newtonian liquids, volatile solvents, surfactant effects and when alternate methods should be considered.

Typical use and users

Laboratories performing surface-tension and interfacial measurements, coatings and paint manufacturers, R&D groups developing liquid formulations, quality control and contract testing bodies, and academic researchers studying wetting and coating behavior.

Related standards

ISO 19403 is a multi-part series on wettability; related parts include ISO 19403-1 and ISO 19403-2 (surface free energy by contact-angle methods) and ISO 19403-4 (polar and dispersive fractions from interfacial tension). The document also references other surface-tension methods such as EN 14370 and ISO 1409 and cross-references ISO 3219-1 for rheological definitions applicable to non-Newtonian liquids.

Keywords

surface tension; pendant drop; drop-shape analysis; wettability; paints and varnishes; liquid coatings; test method; non-Newtonian; surface energy; interfacial tension.

FAQ

Q: What is this standard?

A: ISO 19403-3:2024 is the second edition (2024) of the ISO test method that specifies how to determine the surface tension of liquids using the pendant-drop optical method; it is part of the ISO 19403 series on wettability.

Q: What does it cover?

A: It covers apparatus, specimen preparation, formation and imaging of pendant drops, image analysis and the calculations required to obtain surface-tension values, plus guidance on uncertainty and limitations (notably for non-Newtonian fluids).

Q: Who typically uses it?

A: Test laboratories, coatings manufacturers, R&D and quality-control engineers, and researchers concerned with liquid coatings, wetting behaviour and interfacial properties.

Q: Is it current or superseded?

A: Current — ISO 19403-3:2024 (Edition 2) was published on 4 September 2024 and replaces the earlier 2017 edition.

Q: Is it part of a series?

A: Yes — it is Part 3 of the ISO 19403 series (Wettability), which includes other parts addressing contact-angle methods and decomposition of surface-tension components.

Q: What are the key keywords?

A: Surface tension, pendant drop, wettability, paints and varnishes, drop-shape analysis, surface energy, interfacial tension, liquid coatings.