ISO 17131:2020 Leather — Identification of leather with microscopy.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 15987 apply.
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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 ×.
NOTE For some materials it is necessary to use a microscope with a magnification of 500 ×.
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.
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.
5.6 Reference materials, with known designation.
6.1 From the material being tested, cut two test pieces approximately 10 mm × 10 mm using a suitable cutting device and then section each of the test pieces in accordance with 6.2 or 6.3.
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 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.
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