ISO 17131-2020 pdf free download.Leather- Identification of leather with microscopy.
This document specifies a method using microscopy to identify leather and distinguish it from other materials. The method is not applicable for identifying specific leathers (e.g. sheep leather).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 17186, Leather — Physical and mechanical tests — Determination of surjáce coating thickness EN 15987, Leather — Terminology — Key definitions for the leather trade
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 15987 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.clectropedia.org/
4 Principle
A cross-section of the material is cut perpendicular to the surface. The material structure is compared with typical pictures or known samples by means of microscopy.
The method should be carried out by operators experienced in material identification by microscopy.
5 Apparatus and materials
5.1 Light microscope (optical, phase-contrast or stereo) or scanning electron microscope, capable of giving a normal magnification of at least 20 x
NOTE For some materials it is necessary to use a microscope with a magnification of 500 x.
5.2 Razor blade, capable of cutting a clean cross-section in leather, if the microscope illuminates from above or a scanning electron microscope is used.
5.3 Cryomicrotome. if the microscope illuminates from below or a phase-contrast microscope is used.
6 Procedure
6.1 From the material being tested, cut two test pieces approximately 10 mm x 10 mm using a suitable cutting device and then section each of the test pieces in accordance with 2 or 3.
6.2 Place the cutting edge of the razor blade (52) with the blade perpendicular to the surface and press the blade through the whole thickness of the test piece, ensuring that the blade remains vertical and the section is cleanly cut. lithe test piece is considered to be leather, make the cut with the flesh or inner side uppermost.
NOTE I It is useful to prepare the second test piece section perpendicular to the first.
NOTE 2 A section made as in 6.2 Is suitable for examination under a microscope Illuminated from above or by scanning electron microscopy.
6.3 Place the leather sample soaked in water in a cryomicrotome (5.3) and cut a slice of appropriate thickness.
NOTE A section made as in 6.3 is suitable for examination under a microscope illuminated from below or a phase.contrast optical-microscope. It is useful with a dark sample or a sample with transparent coating.
6.4 When using a scanning electron microscope, ensure that the prepared section adheres to a specimen stub (5.5) with the cut surface uppermost. Coat the stub and section in the coating unit (5.4) so that good image quality can be obtained.
6.5 Place the sections under the microscope and compare the material structure with Figures A.1 to AJ2 in Annex A (scanning electron microscope photos), Figures 8.1 to fiJi in Annex B (light microscope photos) and/or Figures C.1 to C.3 in Annex_C (phase contrast cross-section photos), or with known reference materials (5.6). Use a suitable magnification to distinguish the typical fibre structure of leather from other materials. Consider the appropriate terms for leather defined in EN 15987.
For the absolute identification of leather it is necessary to identify the more or less intact original fibrous structure.
6.6 If necessary, determine the surface coating thickness and the total thickness in accordance with ISO 17186. The cryomicrotome method shall only be used for material identification analyses, as the intrinsic original structure of the material can be changed during the sample preparation processes. Additional structure analyses (e.g. total thickness or thickness of coating) on samples prepared for cryomicrotome give false results.ISO 17131 pdf download.