Overview
EN ISO 2815:2003 - Paints and varnishes: Buchholz indentation test (ISO 2815:2003) defines a standardized method to measure the residual deformation of a cured paint or varnish film using a Buchholz indentor. The test records the indentation length produced when a sharp-edged wheel is loaded onto a coating; this length is indicative of the coating’s resistance to indentation (residual deformation). The method applies to single or multicoat systems but is not suitable for products containing strong plasticizers.
Key topics and technical requirements
- Scope & purpose: Quantifies residual deformation of coatings by measuring indentation length in millimetres.
- Apparatus: A Buchholz indentation instrument comprising a sharpened tool‑steel wheel (indentor), two feet and a metal block; effective load on the indentor is (500 ± 5) g.
- Measurement:
- Indentor contact time: (30 ± 1) s.
- Measure the shadow of the indentation using a microscope (×20 magnification) with a graduated eyepiece; angle of illumination > 60°.
- Record indentation length to 0.1 mm; perform five tests on different areas and report the mean (rounded to 0.1 mm).
- Timing for measurement: typically (35 ± 5) s after removal of the indentor.
- Validity limits: The standard includes a relationship between indentation length, indentation depth (µm) and minimum coating thickness required for a valid measurement - results outside those limits must be discarded.
- Environmental and conditioning: Standard test conditions are 23 ± 2 °C and 50 ± 5 % RH; panels conditioned at these conditions for a minimum of 16 h unless otherwise specified.
- Precision:
- Repeatability (r): 0.23 mm
- Reproducibility (R): 0.45 mm
- Limitations: Not suitable for coatings with strong plasticisers and only valid above certain film-thickness thresholds.
Applications and users
- Quality control in paint and varnish production - quick assessment of film deformation resistance.
- R&D and formulation - compare additives, film-formers or cure schedules.
- Independent test laboratories and certification bodies - routine or contract testing to EN ISO 2815:2003.
- Specifiers and end-users - verify performance claims for protective or decorative coatings where indentation resistance is relevant (e.g., furniture, appliances, industrial finishes).
Related standards
- ISO 1513 - sample examination and preparation
- ISO 1514 - standard test panels
- ISO 2808 - determination of film thickness
- ISO 15528 - sampling for paints and varnishes
Keywords: Buchholz indentation test, EN ISO 2815:2003, paints and varnishes, indentation length, coating thickness, test panels, indentor, paint quality control.