Overview
EN ISO 21546:2020 (ISO 21546:2019) specifies a standardized test method for determining the resistance of coatings to rubbing using a linear abrasion tester (crockmeter). The method uses a loaded abrasion tool, lined with agreed abrasive material and, where applicable, an abrasive medium that is moved linearly over the test surface. While primarily for paints and varnishes, the procedure can also be applied to other material surfaces such as plastics and metals.
Keywords: EN ISO 21546:2020, ISO 21546:2019, crockmeter, linear abrasion tester, resistance to rubbing, rub resistance test, paints and varnishes.
Key topics and technical requirements
- Test principle: A loaded abrasion tool is linearly reciprocated over a specimen; the friction mark is assessed visually or by measuring change in gloss, haze or brightness.
- Procedure variations: Three abrasion-tool geometries (A, B, C) are defined:
- A - cuboid contact, base 22 × 22 mm, test load (22.0 ± 0.5) N (flat panels).
- B - front surface, Ø 16 mm, test load (9.0 ± 0.2) N (original variation for flat panels).
- C - lateral surface, Ø 44 mm × 25 mm, test load (9.0 ± 0.2) N (flat and curved specimens).
- Apparatus specifications: Linear abrasion tester (manual or motor-driven). Motoric versions require an operation counter, stroke frequency (1.0 ± 0.1) Hz and constant velocity across the measurement area.
- Stroke and assessable mark: The assessable friction mark length is specified as (100 ± 30) mm; stroke length selection must account for tool contact expansion.
- Specimen preparation & environment: The standard references conditioning, film thickness and testing climate requirements (see ISO 2808, ISO 3270).
- Evaluation & precision: Methods of assessing rub damage (visual, gloss/haze change) are given. Clause information on precision, including repeatability (r) and reproducibility (R) limits, is provided.
Applications and who uses it
- Quality control and production: Coating manufacturers and QC labs use the test to verify rub resistance during production and batch acceptance.
- R&D and formulation: Materials scientists and coatings formulators compare abrasive durability of prototype formulations.
- Conformance and specifications: Product certifiers and procurement teams refer to EN ISO 21546 when specifying rub-resistance requirements for architectural, automotive, furniture, and industrial coatings.
- Test laboratories: Accredited test houses implement the procedure for comparative testing of paints, varnishes, plastics and coated metals.
Related standards
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 2808 - Determination of film thickness
- ISO 3270 - Conditioning and testing temperatures/humidities
- ISO 1514, ISO 105-F09, ISO 23321 (and ASTM D2240, FEPA standards) - referenced for materials, abrasives and auxiliary requirements
EN ISO 21546:2020 is a practical, repeatable method for assessing rubbing/abrasion resistance using a crockmeter, enabling objective comparison of coating durability across applications.
