Overview
EN ISO 15184:2020 - Paints and varnishes: Determination of film hardness by pencil test (ISO 15184:2020) defines a rapid, practical method to assess the film hardness of coatings by pushing pencils of known hardness across a coated surface. The test applies to a single coating or the top layer of a multi-coat system on smooth surfaces. Results provide a relative rating (the hardest pencil that does not visibly mark the film), useful for quality control, R&D comparisons within a series, and production checks.
Key topics and technical requirements
- Test principle: A pencil lead with defined geometry is pushed across the film at an angle of 45° with a force of (7.35 ± 0.15) N. The pencil hardness is increased until visible marking occurs. The result is the highest hardness producing no mark.
- Apparatus: Metal block test instrument with non‑scratching wheels, a cylindrical pencil holder inclined at 45°, a level, and means to apply/adjust the test force.
- Pencils: Standard wooden (or compatible mechanical) pencils covering the 9B → 9H scale (e.g., 9B, 8B ... HB ... 8H, 9H). Use the same manufacturer/batch for comparative testing where possible.
- Accessories: Special sharpener that removes wood only (leaving the cylindrical lead), abrasive paper (No. 400), soft cloth and solvent for cleaning.
- Specimen preparation: Panels prepared per ISO 1514, sampling per ISO 15528, and conditioning at (23 ± 2) °C, (50 ± 5) % RH for a minimum of 16 h unless otherwise agreed.
- Coating thickness: Measured by procedures in ISO 2808; surface must be smooth for valid results.
- Interpretation limits: The method is not suited for precise cross-product hardness ranking - it is intended for relative ratings among panels with significant hardness differences.
Applications and users
- Quality control and production testing in paint and varnish manufacturing
- Formulation development and comparative R&D for coatings chemists
- Independent test laboratories and inspection bodies performing acceptance tests
- Specifiers and end-users checking top-coat resistance on smooth substrates
This standard helps identify coatings that meet a minimum resistance to marking and offers a fast screening tool for process control and material comparison within a defined series.
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 1514 - Standard panels for testing
- ISO 2808 - Determination of film thickness
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 15528 - Sampling for paints and varnishes
EN ISO 15184:2020 is published by CEN/ISO and supersedes earlier editions; use it when implementing a standardized pencil test for coating film hardness.
