Overview
ISO 17235:2015 - Leather - Physical and mechanical tests - Determination of softness - specifies a non‑destructive method to measure the softness of non‑rigid leathers (e.g., shoe upper leather, upholstery, leathergoods, and apparel leather). The standard defines the test principle, apparatus, sampling/conditioning, test procedure and reporting requirements so results are repeatable and comparable across laboratories and production sites.
Key topics and technical requirements
- Test principle: A cylindrical load pin and defined mass are lowered onto a clamped leather area; the resulting distension (deflection) is recorded as the softness.
- Apparatus basics: Test machine with circular aperture (nominal diameters 35 mm, 25 mm, 20 mm), clamps, a cylindrical load pin (diam. 4.9 mm) with a combined mass ~530 g, guided travel limited to 11.5 mm, and a gauge readable to 0.1 mm.
- Load and timing: The load pin must travel its permitted 11.5 mm in 1.5 s ± 0.5 s. Static effective total test force is specified (including a small, linearly decreasing spring component) to ensure consistent loading.
- Sampling & conditioning: Leather samples are conditioned and prepared in accordance with ISO 2419 (sample preparation and conditioning) and sample locations per ISO 2418; measurements may be taken without cutting a sample from the hide.
- Procedure & replication: Select appropriate aperture (35 mm for firmer leathers, 25 mm for moderate softness, 20 mm for softer leathers). Measure at least three separate, non‑overlapping areas and report individual readings and the mean value.
- Test report: Must reference ISO 17235, specify aperture(s), test areas, individual and mean readings, conditioning atmosphere, any deviations, and full sample identification.
Applications
- Quality control in tanneries and leather finishing operations to verify softness specifications.
- Incoming inspection for footwear, upholstery, apparel, and leathergoods manufacturers.
- R&D and product development when comparing treatments, finishes or alternative tanning processes.
- Supplier certification and specification compliance in procurement and contract testing.
- Non‑destructive testing enables measurement on production cuts or assembled components without ruining material.
Who uses this standard
- Leather technologists, laboratory technicians, quality managers, product developers, and procurement professionals in footwear, furniture, automotive, apparel and accessory industries.
- Test laboratories seeking standardized, repeatable measures of leather softness.
Related standards
- ISO 2418 - Leather - Sampling location
- ISO 2419 - Leather - Sample preparation and conditioning
- IULTCS/IUP 36 (equivalent reference)
Note: Annex A lists commercial apparatus sources for convenience; inclusion does not imply ISO endorsement.