Overview
ISO 17236:2016 is an international standard specifying a method for determining the extension set of leather. Primarily intended for upholstery leather, the standard applies to all types of flexible leathers and focuses on physical and mechanical testing. The extension set measurement assesses the leather's permanent deformation after cyclic stretching, which is crucial for evaluating durability and performance under mechanical stress.
Developed by the International Organization for Standardization (ISO) in collaboration with the International Union of Leather Technologists and Chemists Societies (IULTCS) and the European Committee for Standardization (CEN), ISO 17236:2016 ensures consistency and reliability in leather testing globally. The standard outlines sample preparation, testing procedures, and how to express and report results for accurate quality control.
Key Topics
- Scope and Application: Evaluates extension set of upholstery and flexible leathers to determine permanent elongation after repeated stretching cycles.
- Sample Preparation: Defines cutting six test pieces, balanced across grain direction relative to the backbone-three parallel and three perpendicular-ensuring comprehensive directional data.
- Testing Apparatus:
- Tensile testing machine with precise force measurement (ISO 7500-1 accuracy).
- Thickness gauge compliant with ISO 2589.
- Press knife and ruler for sample cutting and measurement.
- Testing Procedure:
- Test pieces are cyclically extended to a force of 20.0 N ± 0.5 N at a controlled speed.
- After five stretch cycles, permanent extension is measured after a rest period of 60 seconds.
- Calculation of Extension Set: Results are reported as the percentage permanent extension relative to the original sample length.
- Test Reporting: Includes mean extension set values, thickness, conditioning atmosphere, any procedural deviations, and sample identification.
Applications
ISO 17236:2016 is essential for industries reliant on leather quality and durability, including:
- Upholstery Manufacturers: Assessing leather deformation characteristics under use conditions to ensure product longevity and comfort.
- Footwear and Apparel: Evaluating flexible leathers to predict performance and maintain mechanical integrity after repeated stress.
- Leather Tanneries and Laboratories: Providing standardized testing protocols for quality control and certification.
- Product Development: Informing material selection and treatment processes to optimize leather flexibility and resistance to extension set.
- Compliance and Certification: Meeting international testing requirements and benchmarks for leather goods sold globally.
By implementing this standard, manufacturers and testers gain reliable data on leather extension properties, facilitating improved product design and consumer satisfaction.
Related Standards
To effectively apply ISO 17236:2016, it is often used in conjunction with the following standards:
- ISO 2418 – Leather: Sampling location guidelines ensuring representative test samples.
- ISO 2419 – Leather: Sample preparation and conditioning protocols critical for test accuracy.
- ISO 2589 – Leather: Determination of thickness, a key parameter influencing mechanical behavior.
- ISO 7500-1 – Verification and calibration of force-measuring systems in tensile testing machines.
- ISO 2419:2012 – Conditioning atmospheres and environmental factors affecting leather testing.
These related standards form a comprehensive framework supporting mechanical testing, ensuring that results are reproducible, traceable, and standardized across international laboratories.
Ensuring adherence to ISO 17236:2016 enhances leather quality assessment through a validated method for extension set determination. This facilitates better evaluation of leather's mechanical performance, driving higher standards in product development, quality control, and regulatory compliance within the leather industry.