Overview
EN ISO 11998:2006 - "Paints and varnishes - Determination of wet‑scrub resistance and cleanability of coatings" - is a CEN-endorsed ISO test standard that defines an accelerated laboratory method to evaluate a coating’s resistance to wear from repeated wet cleaning (wet‑scrub resistance) and a method to assess cleanability (removal of soiling agents). The standard is intended for comparative testing of dry coating films under defined substrate, application and conditioning conditions.
Key topics and technical requirements
- Test principle: Apply a uniform coating film to a defined test panel, dry and condition it, then subject the film to a fixed number of wet‑scrub cycles and determine mass loss to calculate mean loss in film thickness.
- Wet‑scrub cycles: Standard test exposure is 200 scrub cycles; some classification schemes may use fewer cycles.
- Apparatus & consumables: Specified equipment includes a film applicator (10–15 mm/s), a reciprocating wet‑scrub tester (stroke length (300 ± 10) mm, ≈(37 ± 2) cycles/min), a scrub pad holder (downward force ≈ 135 ± 1 g) and a non‑woven abrasive pad (≈ 90.0 × 39.0 mm). A fresh pad is used for each test.
- Washing liquid: A 2.5 g/l solution of sodium n‑dodecylbenzenesulfonate in water (ISO 3696 grade 3) is specified for wetting the surface before scrubbing.
- Measurement & results: Panels are weighed before and after testing (analytical balance to 1 mg); loss in mass is converted to mean film‑thickness loss for classification or comparison.
- Cleanability: The method for measuring cleanability is specified, but the actual soiling agents and their application must be agreed between interested parties (the standard does not mandate specific soiling agents).
- Limitations: Results depend on substrate, application method and drying conditions; findings are comparative for the defined test setup and not direct predictors of in‑service performance.
Practical applications and users
- Paint and varnish manufacturers - product development, formulation optimisation and QC.
- Test laboratories - standardized evaluation for product claims and certifications.
- Specifiers and architects - selecting coatings for areas requiring frequent cleaning (e.g., hospitals, schools, commercial interiors).
- Certification bodies and standards committees - classifying coatings by scrub resistance and cleanability.
- Industrial users - assessing suitability of coatings for maintenance regimes.
Related standards
- ISO 1513 (sample prep), ISO 3270 (conditioning), ISO 3696 (water quality), ISO 15528 (sampling). EN 13300 is an example of a classification standard that references scrub testing for performance classes.
Keywords: EN ISO 11998:2006, wet‑scrub resistance, cleanability of coatings, paints and varnishes, scrub cycles, test method, abrasive pad, film applicator.