Overview
EN ISO 6860:2006 (ISO 6860:2006) specifies an empirical bend test (conical mandrel) used to assess the resistance of paint, varnish and related coatings to cracking and/or detachment from a metal substrate when bent around a conical mandrel. The procedure applies to single and multi-coat systems (each coat can be tested separately or the complete system) and is widely used for quality control, product development and comparative evaluation of coatings.
Key topics and technical requirements
- Scope: Tests coating resistance to cracking/detachment under standard bending conditions.
- Apparatus: A truncated conical mandrel mounted horizontally. Cone dimensions:
- Small diameter d0 = 3.1 ± 0.1 mm
- Large diameter d1 = 38 ± 0.1 mm
- Length l = 203 ± 3 mm
- Test panels / substrate: Burnished steel, burnished tinplate or soft aluminium, typically ~75 × 150 mm, max thickness 0.8 mm. For aluminium, metallurgical rolling direction should be 90° to the cone axis.
- Coating preparation: Panels prepared per ISO 1514; coating thickness measured per ISO 2808. If brushed application is used, brush marks should be 90° to the cone axis.
- Conditioning: Dry/stove and condition at (23 ± 2) °C and (50 ± 5) % RH for at least 16 h before testing.
- Procedure:
- Perform triplicate determinations.
- Insert coated side toward draw bar, clamp, and bend the panel 180° over the cone in 2–3 s.
- Optional incisions: parallel to short edges at 20 mm spacing to control crack propagation.
- Examine immediately using ×10 magnification (or unaided eye if agreed), measure crack length from the small end to the last visible crack and report the mean in millimetres.
- Precision: Repeatability r = 23 mm; reproducibility R = 46 mm.
- Reporting: Include product ID, reference to ISO 6860:2006, test conditions, coating thickness, any deviations, measured result (nearest mm), examiner name and date.
Applications and users
- Quality control in paint and varnish manufacturing.
- R&D and product comparison for coating flexibility and adhesion performance.
- Contract compliance for industrial coatings on metal substrates (automotive, appliances, metal furniture, architectural metalwork).
- Primary users: coating formulators, testing laboratories, quality engineers, specification writers and regulatory bodies.
Related standards
Keywords: EN ISO 6860:2006, ISO 6860, bend test, conical mandrel, paints and varnishes, coating cracking resistance, coating adhesion test, test panels.