ISO 5402-1:2022

Overview

ISO 5402-1:2022 - Leather: Determination of flex resistance - Part 1: Flexometer method specifies a standardized laboratory procedure to measure the dry and wet flex resistance of leather and leather finishes. The method applies to all flexible leathers under 3.0 mm thickness and uses a reciprocating flexometer apparatus to produce a running fold while counting flex cycles and inspecting for damage.

Key topics and technical requirements

• Scope and purpose: Determines how many flex cycles a leather sample withstands without visible damage; used to define performance criteria for end uses.
• Apparatus: A flexometer with a movable upper clamp and fixed lower clamp, plus a counter. Key parameters:
  • Upper-clamp reciprocation angle 22.5 ± 0.5° at 100 ± 5 cycles/min.
  • Two permitted upper-clamp geometries (Specification 1 and 2); clamp type and manufacturer must be reported.
  • Vertical distance between upper-clamp ledge and lower-clamp edge 25.0 ± 0.5 mm.
• Sample prep and conditioning:
  • Sampling per ISO 2418; specimen preparation and atmospheric conditioning per ISO 2419.
  • Wet testing requires immersion using distilled/deionized water (ISO 3696 grade 3) in a desiccator with vacuum cycles to <4 kPa.
• Test procedure:
  • Samples folded grain-to-grain and clamped so the fold runs along the upper clamp ledge.
  • Selectable flex cycles (examples): dry - 500 to 250 000 cycles; wet - 500 to 50 000 cycles.
  • Periodic inspection with naked eye, 4–6× magnifier and optional stereo microscope; wet specimens re-wetted every 25 000 cycles if applicable.
• Reporting: Record clamp specification, number of cycles, conditioning, observed damage, and any deviations from procedure.

Applications and users

ISO 5402-1:2022 is widely used in:

• Tanneries and leather manufacturers for quality control and product specifications.
• Footwear, upholstery, automotive leather, and leather goods manufacturers to verify durability under flexing.
• Independent testing laboratories and R&D teams assessing finishes, coatings or novel leather treatments.
• As a pre-treatment for other mechanical or aging tests to simulate service wear.

Practical benefits include consistent durability benchmarking, improved product specifications (defining required flex cycles), and comparability across suppliers and markets.

Related standards

• ISO 2418 - Sampling location for leather tests
• ISO 2419 - Sample preparation and conditioning
• ISO 3696 - Water for analytical laboratory use (grade 3)
• Other parts of the ISO 5402 series (see ISO website for the list)

Keywords: ISO 5402-1:2022, flex resistance, flexometer method, leather testing, dry flex, wet flex, tanneries, test laboratories, leather durability.