Overview
EN ISO 1524:2020 - Paints, varnishes and printing inks - Determination of fineness of grind (ISO 1524:2020) specifies a laboratory method for measuring the fineness of grind of liquid paints, inks and related products using a graduated gauge expressed in micrometres (µm). The method applies to most liquid coatings and printing inks but excludes products containing flake pigments (e.g. glass flakes, micaceous iron oxides, zinc flakes). This edition updates the 2013 version and allows gauge materials other than hardened steel, adds three‑groove gauges, and clarifies scraper and reading procedures.
Key topics and technical requirements
- Scope and definitions: Defines fineness of grind and related terminology (see ISO 4618).
- Apparatus:
- Gauge: block (typical dimensions ~175 × 65 × 13 mm) with one, two or three tapered grooves (examples: 25 µm, 50 µm, 100 µm maximum depth). Recommended graduation intervals and ranges are provided for each gauge size.
- Scraper: single‑ or double‑edged steel blade with rounded edge (radius ~0.25 mm) and length slightly greater than gauge width.
- For water‑dilutable paints, stainless steel gauges are recommended.
- Sampling and preparation: Follow ISO 15528 (sampling) and ISO 1513 (sample preparation) to obtain representative test specimens.
- Procedure:
- Preliminary gauge selection, then perform the test in triplicate.
- Pour sample into deep end of groove, draw scraper uniformly across the gauge (usual draw time 1–2 s; for lithographic inks use ≥5 s).
- View the wet draw at an angle of (30 ± 2)° and identify where discrete particles/scratches become predominant. Estimate reading to specified resolution (e.g., 5 µm for 100 µm gauge).
- Clean apparatus after each reading.
- Results and precision:
- Record the mean of three determinations to the same accuracy as original readings.
- The standard includes precision information (repeatability and reproducibility limits) and test report requirements.
Applications
- Quality control in formulation and production of paints, varnishes and printing inks to monitor pigment dispersion and particle size.
- Incoming raw material checks and final product certification.
- Process troubleshooting in mills and dispersers where fineness affects colour, gloss, hiding power and printing performance.
- Specification reference for procurement and contractual quality clauses.
Who uses this standard
- Coatings and ink manufacturers, QC and R&D laboratories, testing houses, raw‑materials suppliers, and procurement/specification engineers.
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 15528 - Sampling of paints, varnishes and raw materials
Keywords: ISO 1524:2020, fineness of grind, paints varnishes printing inks, gauge micrometres, drawdown, dispersion quality, paint testing.