ISO 17131:2020

ISO 17131:2020 pdf free.Leather – Identification of leather with microscopy.
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 iluminates from below or a phase- contrast microscope is used.
5.4 Coating unit, sputter or evaporation, including a suitable element or alloy (e.g. gold) for coating, if a scanning electron microscope is used.
5.5 Specimen stubs, suitable for a scanning electron microscope, if 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 f2 or £3..
6.2 Place the cutting edge of the razor blade (5.2) 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. If the test piece is considered to be leather, make the cut with the flesh or inner side uppermost.
NOTE 1 It is useful to prepare the second test piece section perpendicular to the first.
NOTE 2 A section made as in £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 (53.) and cut a slice of appropriate thickness.
NOTE A section made as in .fj 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.S) with the cut surface uppermost. Coat the stub and section in the coating unit (SA) 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 A.12 in Annex A (scanning electron microscope photos), Figures 8.1 to B.12 in Annex B (light microscope photos) and/or Figures C.1 to C3 in Annex C (phase contrast cross-section photos), or with known reference materials (5k). 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.
6.7 Define the designation of the material considering the results of 6.5 and 6.6 and the leather terms definedin EN 15987.
7 Test report
The test report shall include the following:
a)reference to this document, i.e. ISO 17131:2020;
b)the type and origin of the analysed material sample;
c)designation of the material (see 6.7) as leather or another material;
d) method used for identification;
e) if necessary, the thickness of the coating layer and total thickness in accordance with ISO 17186;
f) if requested, photographs of the sections;
g) any deviations from the procedure;
h) any additional information important for the designation;
i) the date of the test.ISO 17131 pdf download.

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