EN ISO 17236:2025

EN ISO 17236:2025：Leather - Physical and mechanical tests - Determination of extension set

EN ISO 17236:2025 specifies a standardized method to determine the extension set (permanent deformation) of leather materials after cyclic tensile loading. Primarily for upholstery leather, it is applicable to all flexible leathers and provides reproducible data for product development, quality control, and compliance testing. This third edition aligns terminology with ISO 2418 and ISO 2419.

Scope and Purpose

(1) Measures the permanent deformation of leather after repeated tensile stress.

(2) Supports assessment of durability and performance in end-use applications.

Testing Principle

(1) A leather test piece is cyclically extended to a defined force, held under load, and then released.

(2) The residual extension is measured and expressed as a percentage of the initial gauge length.

Specimen Preparation and Conditioning

(1) Cut specimens according to ISO 2418.

(2) Condition specimens under standard atmospheres per ISO 2419.

(3) Measure thickness per ISO 2589 to ensure uniformity and accuracy.

Apparatus Requirements

(1) Tensile testing machine calibrated to ISO 7500-1.

(2) Jaws designed to prevent slippage.

(3) Press knife for precise specimen cutting.

(4) Ruler and thickness gauge for measurements.

(5) Stopwatch for timing load cycles.

Test Procedure

(1) Mark specimens with parallel lines to gauge elongation.

(2) Apply five tensile load cycles reaching 20 N ± 0.5 N.

(3) Maintain load for 10 seconds during each cycle.

(4) Measure extension after 60 seconds post-testing.

(5) Calculate extension set percentage using the standard formula.

Results and Reporting

(1) Include specimen identification, environmental conditions, pre-load values, and average extension set.

(2) Record specimen thickness, deviations, and test date.

Applications

(1) Upholstery Leather Quality Control - Ensure dimensional stability under mechanical stress.

(2) Footwear and Leather Goods Testing - Predict product performance during use.

(3) Research and Development - Provide accurate mechanical data for material optimization.

(4) Regulatory Compliance and Certification - Meet customer and regulatory requirements for leather properties.

Related Standards

(1) ISO 2418 - Leather: Specimen preparation and positioning.

(2) ISO 2419 - Conditioning and testing environments of leather specimens.

(3) ISO 2589 - Leather: Methods for measuring thickness.

(4) ISO 7500-1:2018 - Calibration and verification of tensile testing machines.

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2026-01-07 18:25