Overview
ISO 20427:2023 - Pigments and extenders - Dispersion procedure for sedimentation-based particle sizing specifies standardized sample preparation and dispersion methods to determine the particle size distribution of a single pigment or extender dispersed in a liquid. The procedures are optimized for sedimentation-based particle sizing techniques that rely on particle migration under gravity or centrifugal forces and require a density contrast between particles and the liquid phase.
Key topics and technical requirements
- Scope and purpose
- Standardizes dispersion prior to sedimentation-based particle sizing of pigments and extenders.
- Targets separate particles (not multimodal mixtures) dispersed in a liquid medium.
- Principles of dispersion
- Ultrasonic dispersion (probe-type and bath-type): energy density, temperature and particle concentration are critical; energy input needs control and documentation.
- Wet jet milling (high-pressure homogenizer): uses turbulent shear and cavitation; typical pressure range referenced (80 MPa to 245 MPa).
- Shaker-based dispersion: mechanical vibration with specific device parameters (e.g., amplitude and frequency requirements noted in the standard).
- Sedimentation-based sizing techniques
- Stokesian sedimentation analysis as the basis for calculations.
- Methods include gravitational sedimentation and centrifugal techniques (disk-type and cuvette-type centrifuges, centrifugal field-flow fractionation).
- Practical protocol elements
- Apparatus, reagents, sampling, energy input measurement (Annex A), dispersion settings and limits (Annex B).
- Recommended sample preparation recipes and test report requirements.
- Informative annexes
- Specific dispersion procedures for common materials (e.g., TiO2, CaCO3, Fe2O3, carbon black) and a general dispersion procedure.
Practical applications and users
- Quality control and R&D in coatings, paints, inks and pigment manufacturing.
- Analytical laboratories performing particle size distribution measurements using sedimentation methods.
- Process engineers and formulators needing reproducible dispersion recipes for particle sizing.
- Standards and compliance teams ensuring traceable, comparable particle-sizing data across suppliers and laboratories.
Related standards (normative references)
- ISO 13317 series - gravitational liquid sedimentation methods
- ISO 13318 series - centrifugal liquid sedimentation methods
- ISO 3696 - water for analytical laboratory use
- ISO 9276-1 - representation of particle size analysis results
- ISO 15528 - sampling for paints and related materials
ISO 20427:2023 helps ensure reproducible, documented dispersion procedures for reliable sedimentation-based particle sizing of pigments and extenders - a practical reference for labs and manufacturers focused on particle-size quality, comparability and method traceability.