Overview
ISO 8130-13:2019 - "Coating powders - Part 13: Particle size analysis by laser diffraction" specifies a standardized method for measuring the equivalent-sphere particle size distribution (PSD) of coating powders using laser diffraction. The method covers powders with particle sizes from 1 µm to 300 µm (with a note that particles >300 µm may require a different optical model). The standard is specific to coating powders and references instrument qualification and broader measurement guidance given in ISO 13320.
Key topics and requirements
- Measurement range: 1 µm to 300 µm (equivalent-sphere PSD by laser diffraction).
- Optical models: Choice between Fraunhofer approximation (commonly used for coating powders) and Mie theory (requires refractive index and is better for micron/sub-micron ranges). Incorrect model or refractive index can bias the PSD, especially at the fine end.
- Apparatus and environment: Laser diffraction particle size analyser as per ISO 13320; located in a clean, draft‑free, vibration‑free environment. Feeder and dispersing unit suitable for powder shapes. Use contamination‑free compressed air or vacuum for dispersion.
- Sample handling: Representative sampling per ISO 15528; typical sample quantity is 3–5 g. Dispersion should achieve deagglomeration without comminution.
- Test conditions and safety: Standard atmosphere 23/50 class 2 (ISO 291) or agreement between parties. Follow equipment safety (earthing to prevent static ignition); allow laser warm-up and alignment.
- Measurement controls: Target obscuration between 1% and 10%. Instrument performance must be qualified regularly using reference materials or previously characterized samples; log results.
- Limitations and error sources: Laser diffraction is not suitable for oversize material - verify oversize by sieve analysis (ISO 8130‑1) or dynamic image analysis (ISO 13322‑2). Shape and non‑sphericity affect results; dispersion pressure can introduce breakage and alter PSD - optimize dispersion to minimize fine fraction changes.
Practical applications and users
- Quality control and batch verification for coating powder manufacturers and paint/varnish formulators.
- R&D and process control teams monitoring particle size distribution (PSD) to ensure coating performance (flow, coverage, curing).
- Test laboratories and instrument suppliers implementing standardized particle size analysis by laser diffraction.
- Procurement and compliance teams requiring reproducible, comparable PSD data across suppliers and production lots.
Related standards
- ISO 13320 - Particle size analysis - Laser diffraction methods (instrument qualification, general guidance)
- ISO 8130-1 - Coating powders - Sieve analysis for oversize material
- ISO 13322-2 - Dynamic image analysis for particle sizing
- ISO 15528, ISO 291, ISO 8130-14, ISO 9276 series - sampling, atmospheres, vocabulary and PSD representation
Keywords: ISO 8130-13:2019, coating powders, particle size analysis, laser diffraction, particle size distribution, PSD, Fraunhofer, Mie theory.
