Overview
ISO 17131:2020 - Leather - Identification of leather with microscopy specifies a standardized microscopy method to identify whether a sample is leather and to distinguish leather from other materials. It is intended for material-level identification only and does not provide procedures for identifying specific animal leathers (for example, sheep leather). The method relies on cross-section microscopy and comparison with reference images or known materials.
Key topics and requirements
- Scope and principle
- Cut a cross-section perpendicular to the surface and compare the material’s internal fibre structure with reference images or reference materials.
- Identification depends on recognizing the original fibrous structure of leather.
- Apparatus and magnification
- Use a light microscope (optical, phase-contrast or stereo) or a scanning electron microscope (SEM) with normal magnification of at least 20×; some materials may require up to 500×.
- Sample preparation tools: razor blade for top-illumination/SEM sections, cryomicrotome for bottom-illumination or phase-contrast slices.
- SEM requires specimen stubs and coating (e.g., gold) using a sputter/evaporation unit.
- Procedure highlights
- Prepare two ~10 mm × 10 mm test pieces; cut sections per method (razor or cryomicrotome).
- Compare sections to normative Annexes A (SEM photos), B (light microscope photos) and C (phase-contrast photos) or to known reference materials.
- If needed, determine coating and total thickness per ISO 17186 (note: cryomicrotome-prepared samples should only be used for identification, as preparation can alter structure).
- Reporting
- Test report must reference ISO 17131:2020 and include sample origin, material designation (leather or other), method used, coating/total thickness (if applicable), photographs, deviations and test date.
Applications and users
ISO 17131:2020 is practical for:
- Quality control and testing laboratories performing material verification and incoming inspections.
- Manufacturers and tanneries verifying raw materials or finished goods.
- Product authentication and compliance teams distinguishing leather from synthetic alternatives or leather-like materials.
- Customs, regulators and forensic analysts assessing product claims, origin and labeling.
- Research and academic labs studying leather structure and comparative materials.
Operators should be experienced in microscopy-based material identification to ensure reliable results.
Related standards
- ISO 17186 - Leather - Determination of surface coating thickness (referenced for coating/thickness measurements)
- EN 15987 - Leather terminology and key definitions (used for appropriate leather terms)
Keywords: ISO 17131:2020, leather identification, microscopy, SEM, cryomicrotome, phase-contrast microscope, leather testing, cross-section analysis.