Overview
ISO 21546:2019 specifies a standardized laboratory method to determine the resistance of coatings to rubbing using a linear abrasion tester (crockmeter). The test uses a loaded abrasive tool that is moved linearly over the coated surface; it applies to paints and varnishes and can also be used on plastics, metals and other material surfaces. The standard defines test principle variations, apparatus, specimen preparation, test conditions, evaluation and reporting to ensure repeatable abrasion-resistance data.
Key topics and technical requirements
- Test principle: A loaded abrasion tool lined with an abrasive material and, if required, an abrasive medium, is moved back and forth over the specimen to produce an assessable friction mark. Evaluation can be visual or by measurement of gloss, haze or brightness.
- Procedure variations: Three abrasion-tool configurations (A, B, C) are defined to suit flat or curved specimens. Selection depends on sample geometry and desired friction-mark characteristics.
- Test loads:
- Abrasion tool A: 22.0 ± 0.5 N
- Abrasion tools B and C: 9.0 ± 0.2 N
- Apparatus:
- Linear abrasion tester (manual or motor-driven). Motoric devices require an operation counter and a stroke frequency of 1.0 ± 0.1 Hz, with constant velocity across the 70 mm measurement area.
- Stroke length selected so the assessable friction mark is (100 ± 30) mm.
- Abrasion tool specifics (selected examples from the standard):
- Tool A: felt insert (22.0 × 22.0 × 6 mm), felt bulk density 0.44 g/cm3.
- Tool B: cylinder, Ø 16.0 ± 0.1 mm (front-surface contact).
- Tool C: curved tool radius 19.0 ± 0.5 mm, EPDM rubber cover (3.0 ± 0.3 mm thick) with hardness 60 ± 5 Shore-00 and bulk density 0.16 ± 0.02 g/cm3 - suited to curved specimens.
- Ancillary materials: Felt cloth specification (1.5 mm thickness, bulk density 0.28 g/cm3, DIN 61200 - M5), FEPA abrasive grain references and conditioning per ISO 3270.
- Quality and statistics: The standard includes sections on precision (repeatability and reproducibility limits) and required test-report contents.
Applications and who uses it
- Quality control and acceptance testing for automotive, architectural, industrial, marine and consumer coatings.
- R&D and formulation development to compare abrasion resistance across coatings and substrates.
- Materials testing laboratories and manufacturers of paints, varnishes, plastics and coated metal components.
- Specification writers and procurement teams who need standardized abrasion-resistance data for supplier comparison.
Related standards (referenced)
- ISO 3270 (conditioning), ISO 2808 (film thickness), ISO 4618 (terms and definitions), ISO 105‑F09 (rubbing cloth), ASTM D2240 (durometer hardness), FEPA abrasive specifications.
Keywords: ISO 21546:2019, crockmeter, linear abrasion tester, resistance to rubbing, abrasion test, paints and varnishes, coating durability, abrasion resistance testing.
Open preview (PDF)Paints and varnishes — Determination of the resistance to rubbing using a linear abrasion tester (crockmeter)