Overview
ISO 3379:2024 - Leather - Determination of distension and strength of surface (ball burst method) specifies a standardized laboratory test to measure how the leather grain or finished surface stretches and resists rupture when distended by a hemispherical ball. The method is applicable to all flexible leathers and is especially relevant for assessing lastability of footwear uppers. The third edition updates terminology and test-piece preparation to align with recent ISO leather standards.
Key topics and technical requirements
- Test principle: A circular leather specimen is clamped around its edge and distended by a hemispherical steel ball mounted on a plunger acting from the reverse side. Record the distension and force at first surface cracking (first damage) and, if applicable, at burst (complete rupture).
- Specimen and preparation:
- Cut at least three circular test pieces (one per hide if batch >2) using a press knife as per ISO 2418.
- Condition specimens per ISO 2419 and measure thickness per ISO 2589.
- Apparatus:
- Clamp aperture: 25.0 mm ± 0.5 mm diameter, designed to prevent slippage or unwanted stretching of the clamped area.
- Plunger: hemispherical end, nominal diameter 6.25 mm ± 0.05 mm.
- Plunger travel speed: 0.20 mm/s ± 0.05 mm/s (no rotation).
- Measurement accuracy: distension (plunger travel) ±0.05 mm, force ±10 N.
- Procedure highlights:
- Set zero distension using a rigid flat reference.
- Distend continuously and observe wearing surface for cracking; record distension to nearest 0.1 mm and force to nearest 10 N.
- Special note for patent leather: grain may crack before the surface film-visual cues and force drops can indicate cracking.
- Reporting: Include reference to ISO 3379:2024, specimen ID and thickness, mean distension and mean force at crack (and at burst if measured), conditioning atmosphere (ISO 2419), deviations from method, and test date.
Applications and users
ISO 3379:2024 is used by:
- Leather manufacturers and tanneries for quality control and product specification.
- Footwear manufacturers to evaluate lastability and suitability of leathers for uppers.
- Test laboratories and R&D teams assessing surface strength, durability, and finish performance.
- Procurement and compliance teams specifying test requirements in contracts and standards-based product acceptance.
Keywords: ISO 3379:2024, leather testing, ball burst method, distension, surface strength, lastability, footwear uppers, grain cracking.
Related standards
- ISO 2418 - Specimen position and preparation
- ISO 2419 - Specimen conditioning
- ISO 2589 - Thickness measurement
- ISO 15115 - Leather vocabulary
- EN 15987 - Leather terminology
This standard helps ensure repeatable, comparable measurements of leather surface distension and strength, supporting quality assurance and material selection across the leather and footwear industries.
